View Full Version : Pistons are melted!!
OK, I was doing high speed runs playing with the clutch and pulling plugs and all the sudden the plug in the 2nd cylinder from the clutch had a missing electrode! All the other plugs looked fine. They were brand new b9ev's with the small electrode and I just came to the conclusion that it broke off! I put a new plug in and it ran fine back into the shop, I pulled the carbs -looked great! put them back together and monkeyed with the clutch. I got it back out today and did 2 more WOT runs - short ones with brand new plugs I cut the power on the last coasted to a stop and pulled plugs -I checked the cylinder I had problems with the day before and the plug was melting! I pulled the rest and 2 of them look a little yellowish tan but the plug in the cylinder on the exhaust side was aluminum dust grey!
I had to run it back into the shop I pulled the heads and this is what I found - the pistons in cylinders 1 & 3 (or 2 & 4) (can someone tell me what way to # the cylinders?) are melting down right over the top ring gap on the intake side!
Whats the cause of this??????!!!!!!!! The other 2 cylinders look fine IMO
could it be something with the rings? ring butting or too much of a gap? or could I have an airleak somewhere? I just that would cause melting on the exhaust side.
I just talked to a guy from indy specialties and he says 9 out of 10 times intake side wear is caused from pre detonation! Either through bad gas or bad CDI not retarding timing properly! This was fresh 93 octane gas I put in a week or so ago to a drained tank, I also added a can of octane boost this morning before I took her out. So I guess its still possible it was bad from the pump or something, I dont know!
Anyone have any experience with this sort of thing? How would I know if my timing wasnt retarding?
I guess I should also add that Ive been having some trouble at WOT - it hits 8300 or so (right were I want to be) and then falls off to about 6500 and stays there till I let off and go again! I assumed this was a clutching problem, but I wonder if its not related!
JAMIE
12-13-2005, 06:49 PM
i'd stay away from that octane boost...!i read an awsome article in engine masters magazine and they claimed that in most cases it will lower the octane.i've personaly had nothing but bad experiences with octane booster it's nothing at all or add real race gas.my pistons looked exactly like yours.might be more favorable for 4 srokes .my 2cents.
JAMIE
12-13-2005, 06:52 PM
to my knowledge cylinders run from left PTO would be 1 and recoil cylinders would be 4.
Thanks Jamie, So your sayin your pistons have melted on the intake side before as well?
mtbombsqd
12-13-2005, 07:53 PM
What was the weather like? Have you check the boots for any possible air leaks, or air leaking through the base gaskets. Looks like your running pretty lean to me, can't see any pistson wash. I've cold seized pistons on a very cold day, when I didn't warm the motor up long enough. That was with weisco pistons which are thinner on top and expand faster than the cylinder walls, that damage showed up on the exhaust side. Not sure if the melting at the ring keeper indicates that or not. Luckily you didn't drop a rod and saw the motor in two, I've done that also.
YAMMIEGOD 3:16
12-13-2005, 08:03 PM
DUDE, GET CDI AND TIMING OUT OF YOUR HEAD. A BAD KILLS ENGINE STONE DEAD. THIS WAS EITHER CAUSED BY BAD GAS OR YOUR TOO LEAN. ALSO YOU HAVE STATED YOU BEEN MAKING ALOT OF WOT RUNS, HOW HOT IS THIS ENGINE GETTING ? ARE YOU OVERFLOWING INTO OVERFLOW. REMEBER WITH QUADS TODAY, YOU MUST RUN GOOD GAS. THE RPM DROP OFF WAS PROBLEY THIS PISTON STARTING TO GO DOWN BY LOOSEING COMPRESSION FOR STARTERS. I WOULD GET IT BACK TOGETHER AND UP JETTING ACROSS THE BOARD, THAN FIND SOME RACE GAS AND PREMIX IT WITH YOUR 93. 3:16 (tony)
Skinner
12-13-2005, 09:11 PM
The fastest way to burn down a 2 stroke is to have water in the gas. The other thing is to run it lean.
Same thing Tony's tellin ya
Premium fuel sits in the tank all summer, few people use it, maybe high perf outboards, quads. Their underground and they condensate
Up the jetting, drain the fuel tank, put GOOD gas in it
Its cheaper to rejet than to rebuild
Well thats something I forgot to bring up as well, sorry but Ive got my head spinnin tryin to figure this out.
This is a fresh upper rebuild, new pistons honed cylinders raised cylinders with .039 base gaskets and heads cut .032 - I had 142 psi when I first put it together and checkin it before I just now tore it down was 120 dead even across the board! All the cylinders were the same! Where did my 22psi per cylinder go?
This motor is always good and warmed up before I actually run it, nothin to do with a cold seize. Could it be a crank seal maybe, I just cant figure out why a lean condition wouldnt melt the exhaust side of the pistons? Ive never seen pistons melted on the intake side - unless its got something to do with the cylider lift and the swirl of the charge from the ports thats pushing the charge to the intake side for ignition or somethin? or maybe its the quads makin it run cooler on the exhaust side so a lean condition actually makes more heat on the intake side?
Yeah Yammie Ive got some coolant comin into overflow. And man I hate to put it back together not knowin the problem. I dont know I just need to have all this stuff added up and try to be able to make sense of it so I can fix it right!
Pistons 2 & 4 burned on intake side
Drops RPMs to 6500 shortly after hitting peak of 8300
Lost 20+psi per cylinder with less than ~ 3hrs on motor
Hey Skinner, Long time no talk!
Thats what the guy from Indy told me. 1st thing to do in morning is drain gas into clear container and inspect. But how does that relate to the lost RPMs and lost compression?
I just want to make sure I can put this thing back together and fix it with good gas and jetting. Is there anyway this could be a crank seal or somethin else that I could or should fix right now while its apart?
mtbombsqd
12-13-2005, 11:26 PM
When you increased the base gasket and milled the head you changed and actually shortened the intake duration. Did you increase jetting to compensate? YAMMIEGOD is right on about the fuel. I talked with Pat Hauck about compression and pump gas. He old me 92 octane is fine up to 136 psi and above that start mixing 110 octane. It would seem to me with the shorter intake duration and higher compression you would have created a lean condition from the start. There used to be a post on this site concerning just that, with all the new changes I'm not certain it's still here. Ofcourse check your crank seals, base gaskets, and boots for airleaks when rebuilding. Compression loss came from piston melting and probably sticking the rings. The motor will probably run at 95 psi, your compression would have started down hill from the first WOT. Check your other 2 pistons I would imagine they are pretty close to the same condition after close inspection.
Izz,
That really sucks!
I take it that this is on your 800?
Did you make any other changes when you raised the cylinders? Air boxes, vent lines, head gasket, jetting?
I think that your compression was kinda high to be running on pump premium. As far as octane boost goes it will raise the octane of regular grade fuel but do little or nothing when added to pump premium.
Ken
My other 2 pistons are great looking, no sign of even the slightest wear! Although the compression on those cylinders was 120 also! What would explain this? How can you check a crank seal? Or would that even cause low compression? The base gaskets look fine still and they were brand new. The boots are all good and were nice n snug!
Im running 152.5's for jetting and Im shocked that would be to lean but hell Ill put 157.5's in when I get it together!
Ive thought about this all night and the only way I can see - to be that hot on the intake side only - is pre detonation. The piston damage is strictly confined to those 2 cylinders and the piston damage is shaped to the intake port!
It would seem to me that I have to be getting detonation before my intake ports are closed by the piston! So that leads me to the gas (as long as theres no way the timing could be off)! Im still not satisfied with why Ive lost compression so evenly across all cylinders ecspecially when those 2 pistons look that bad, youd think those cylinders wouldve been lower. and like I said the other 2 pistons are fine!
Ken, Thanks for responding!
Yeah this is my 800, Ive done all kinds of things I shouldnt do!!! Problem is Im convinced I can get it to work right!!! At this point though I need some sound advice as to why this doesnt add up in my head!
Like I said above this was running on 152.5's and 50 pilots at 2 turns - Airboxes are gutted and vent lines run too them.
Head gasket is stock - but the head was cut to match the cylinder raise + .012 thous (gave me 142 upon assembly)
Im also running PSI modblasters made for a 750
Ive only ran this machine less than 3hrs now with almost all of it at low to mid playing around the yard with the occasional wheelie blast (plugs always looked great) 2 days ago I got it all ready (so I thought) for WOT runs to check clutching! I did 3 short runs (2/10ths of a mile) at WOT and the machine would hit my 8300 and within a couple seconds felt like it shifted and dropped to 6500 rpms and would stay till I let off throttle and restarted.
So I cut the power after the 3rd run and the electrode was gone on b9ev #2 all the other plugs looked fine with the insulator the color of cardboard and the center electrode black. I was freakin out about the #2 cylinder and checked compression, it was 120 (with all the other plugs out of the machine) and all the other cylinders were the same (Although you should know that if I left the other plugs in when I checked compression each cylinder was at 136 - so I dont know if this is right or not? or whats the proper way to do it?) Anyway I put a new plug in and ran it around the yard and checked it again and it was fine. That night I pulled the carbs and cleaned them all over again (looked good) put it together next morning and added a half bottle of Lucas octane booster (I only have about 3 gallons of gas in tank) I warmed it up good and cruised around the yard then did two WOT short blasts again, I pulled the plugs and now #2 and #4 looked grey. And anyway the rest I already have posted!
Skinner
12-14-2005, 08:37 AM
Hey Skinner, Long time no talk!
Thats what the guy from Indy told me. 1st thing to do in morning is drain gas into clear container and inspect. But how does that relate to the lost RPMs and lost compression?
I just want to make sure I can put this thing back together and fix it with good gas and jetting. Is there anyway this could be a crank seal or somethin else that I could or should fix right now while its apart?
Hey Izz, how are ya? I don't have to ask how your day is goin:banghead:
The aluminum color on the one plug may be just that, aluminum. Take your floatbowls off without spilling them and see if theres any water in the bowls. Gas and water will separate and you should be able to see it. Check them all, especially the ones that burned up. That may tell the tale.
As far as the loss of rpm, that could be in spite of
Thermal Nuclear Meltdown. Was the motor hot when you checked compression (120 lbs?) The other thing to look at is the head gaskets, possible trail of coolant into the cylinders. Wondering if you noticed white exhaust. Just read your last post, color of plugs indicate LEAN
Best wishes, hope ya figure it out
Skinner
Skinner thats exactly how I feel :banghead: although Ive got to say I was asking for this fooling with "makin it better"! THe machine was warm I suppose when I checked compression. Whats the right way to do it though, with all the other plugs in or out when your checkin each cylinder? Because Id get two differant readings!
Too late too check the float bowls theyre already cleaned and dry, Im gonna drain the tank in a short while here, Ill let ya know what I find.
jminor
12-14-2005, 08:50 AM
guys with all the mods could the 750 modblasters on the 800 cause a problem? Just throwing it out there.
Just read your edit Skinner, Ill be sure too jet fatter when I get it together then, I have no Idea how too read plugs (just in theory from what Ive read and pictures) Maybe this is the whole problem, too lean?!
But why intake side meltdown? doesnt that have to be pre deto? does bein to lean cause that as well ?
Well I just talked to Hauck's - Should be runnin 160's with my setup! I guess that probably explains alot! He said the Vmax4's are funny with the direction of the ports and that hes seen them burn right down to the pin many times from bein lean, so I feel a little relief (starting to think I can just rejet) He also said exactly what you said mtnbmbsqd about bein borderline for premium and to mix 1 gal race fuel with 4 gal premium for no problems!
Is there anyway to check the crank seals without tearing into the bottom half of the motor? Or is the consensus that thats unnecasary at this point?
YAMMIEGOD 3:16
12-14-2005, 09:34 AM
IZZ, HOW MUCH WATER IN YOUR OVERFLOW. ENOUGH WHERE YOUR TEMP LITE IS COING ON. DUDE, LOOK THING HERE IS THE MELTED TIP OF YOUR SPARK PLUG. THATS CAUSED BY HEAT AND THE BIGING OF DETNATION. SEE THINGS HAPPEN IN STEPS WHEN YOUR READY TO BURN DOWN. USUALLY SHURE SIGN OF DETNATION IS NOT ENOUGH OCTANE. OR LIKE DAVE SAYS WATER IN THE GAS. THESE GUYS ARE ALL ON TRACK HERE, THING YOU MUST REMEBER AND I BRAGGED HARD FOR YEARS HERE ABOUT PSI QUADS OR ANY QUADS FOR THAT MATTER HOW INPORTANT IT IS TO USE GOOD GAS. THESE PIPES WERE MADE 10 YEARS AGO. GAS WAS WAY BETTER THAN JUST BY THE 10% ETHONOL THEY ADD NOW. THAT STUFF ALONE SHOULD MAKE YA JET UP. ALL THE SNOWMOBILE COMPANIES SEE THIS. THATS WHY YAMAHA CAME OUT WITH THE DCS. LOOK, YOU MIGHT HAVE SOMETHING ELSE GOING ON, BUT 91 OCTANE AIN,T ENOUGH. SHIT THEY WANT YA TO RUN ATLEAST 94 10 YEARS AGO WITH QUADS. GET YOUR SELF SOME RACE GAS, PREMIX IT WITH YOUR 91 AT 50/50. GUYS, THIS IS WHAT WE HAVE TODAY. YOU DON,T KNOW WHAT THE GAS IS YOUR ADDING TO YOUR TANK. I KNOW THIS STILL DON,T TELL YA WHAT HAPPENED, BUT MY GUESS IT WAS CAUSED BY LOW OCTANE. ! 3:16 (tony)
My $0.02,
Higher octane fuel.
AND/OR drop your compression, a 92 3-layer head gasket should drop you about 10lbs.
Fatter jetting.
AND/OR put on air boxes with the guts in them.
Take the vent tubes out of the air boxes until you get your problems resolved, it will give you a bit more of a safety factor at higher speeds.
Ken
Skinner
12-14-2005, 02:29 PM
Izz
Hashed this over with my son Dave, reviewed the pictures again. His take on it is If the pistons burnt on the exhaust side, its lean. If its on the intake side (erosion) its detonation. Possible water in the gas, metal paticle floating due to lean, etc. Predetonation usually burns a hole in the top, not erosion. The other thing is the charred crystaline look on the domes. When I told you to study the headgasket, look for a trail from the water jacket to the cylinder. The crystaline is a possibility of burnt glycol. May have overheated due to lean, took out the headgasket and started the detonation. Could be lots of things. Again I ask, did you notice white exhaust???? I think if you would up the jetting, get the vent tubes out of the airbox per Ken, and blend some GOOD fuel, you will be OK. All of the above posts are valid, all these guys have good input. The bottom line is there are to many variables, ya need to narrow them down
Skinner
mtbombsqd
12-14-2005, 06:48 PM
Have you taken the pistons out? I would say the rings are stuck or collapsed. Check the domes make sure nothing has happened to them. There are probably better ways to check the crank case, I would do 1 or both of two options. Seal up the crank case pressure it up and look for leaks, or once you've put it back together and have it running look for air sucking in. When I say seal the crank up, I would remove pistons, install gaskets, jugs and torque the head & 3 plugs. Seal the intake and exhaust. My compresson tester has an attachment that will accept air like a tire valve. Watch the guage for a pressure drop, then find it with a light tissue. thats pretty much shade tree mechanics. Snowgoer from last year had an article on this I believe, I'll check old issues and see. your pistons don't really create the compression the rings do. That motor heats the cylinders pretty equal, compared to twins, more than likely when your cylinders hit a certain temp the damage was done equally across the board. I don't have my manual with me but I believe stock setup at sea level are 143's. 150's with quads and in SE Michigan would seem lean. I've always understood pinging in motors was caused by 2 things, timing advance and low octane for the compression. Increase your jet size and put in 110 octane race gas. I ran 110 in my 96 for acouple of years, motor stayed cool (136 cylinder psi) without any problems, mixed 50/50 motor did ok, mixed 75/25 burnt a cylinder on a cold day. Octane boost does not change the distillation curve of gasoline, its really an additive to burn emissions gases. distillation cure compares different gasolines on completeness of burn, that means a fuel with a higher distillation curve burns more complete, or will not detonate under higher cylinder pressures. Thats why hight compression motors, dragster ect use alcohol, 93 octane wouldn't make it into the cylinder before lighting up. Hope that helps, you might want to give Hauck Motor Sports a call, they have been very helpfull to me and I'm a complete stranger to them.
kielbasa
12-14-2005, 06:53 PM
when I look at the 4th pic, seems to me I clearly see textbook detonation (center of crown eroding away)........sure is weird to meltdown on the intake side though, next time make sure the arrows point toward the exhaust!!!
Pistons are all out, Nothind at all wrong with the rings on the good pistons and the good pistons are good I mean not the slightest hint of wear or stress! Theyre black in the middle though so I guess that means it was lean?! The rings on the eroded pistons are also not seized at all, although I definatly wouldnt reuse them!
I was told by as many people that have told me otherwise now that 140 psi is pump gas safe and thats what I was shooting for! So if thats no longer the case Ill do as Ken says and put another layer of head gasket in to try and lose some compression. Im riding this on trails so racing gas is gonna be out of the question!
I will say this though, last year I rode this sled before I did all the work to it with 1 layer of head gasket as the only mod, it had 132 psi and jetting that youre not even gonna believe! 138.8's with 45 pilots and heres the crazy part - needle all the way down! thats right the clip was in #1 position) I put 800 some UP trail miles on it with premium pump fuel at every stop. So I guess if 142 is gonna detonate premium prematurely I was really walking the line at 132! its either that, or this 93 octane I bought wasnt really 93 octane! and maybe its like yammiegod says take away 2 octane points cause they legally can and still call it 93 - so now your down to 91 - which brings me to my point - like I said I ran 132psi last year running premium with lean jetting and alot of times that premium was from pumps labeled 91, so if you look at it the same way I couldve been runnin 89 octane and I had no problems!
Now I dont know what Im tryin to say Im just stating facts. I personally dont believe that if you had a stock motor and all you did was up compression to 142 psi youd have to run race gas! I think my problem is a result of the snowball effect, and I did call hauck and he told me the same thing - Airboxes gutted with quads =160 mains - no question he said!
You open up the exhaust with quads and then feed it all the air those 33's can pass and your talking some big CFM numbers add into that a boost port hole cut to 3/4" and high compression! I needed way more fuel and at a higher octane than I ever imagined! I (as well as others) thought that 152.5's was way rich to start with, but it turns out that we were way wrong!
Ive drained a gallon of the gas from the bottom of the tank into a big clear jar and let it settle - not a trace of water! (not to say the octane still might be way off)
I dont believe there were any air bubbles in coolong system, I wrestled with bleeding that thing for a day and finally figured it out and coolant ran through the system great. The water temp light never came on at all either during this all (and I know it works because the airbubble thing happened to me last year when I removed the layer of head gasket and the light came on so I had a buddy bleed it for me then)
The head gaskets and tops of cylinders and heads show no signs of a blowed head gasket or coolant coming into the cylinders. The only thing I found upon inspection of heads and cylinders was the melted residue of the pistons on #2 and #4 it was in the squish band of the cylinders on the intake side and the dome in the heads on that side as well. It took forever to remove it all without hurting the parts. I figure this is probably normal for what happened to the pistons but holy hell there was alot of heat in that area! So I dont know maybe there wasnt good coolant flow there or an airbubble, it is the high side of the heads so Im not ruling it out!
I guess the conclusion Im gonna draw from all this, is that I was way too lean even though 3 jet sizes doesnt seem that drastic for the short runs Ive taken, I guess it was and Ill probably even start a little higher than 160's to be safe this time (I never thought Id hear of someone running over 150's in a vmax4) Im also putting my needle clips in #4 to raise them a little as well.
Well my parts are on the way and God willing it will be back together Saturday!
Thanks to everyone! For all the help and opinions and stories of similar woes! You guys have been so much support! Without which there would be only 1 other tool I would need to fix this machine - a BIG hammer!
P.S. Skinner I dont recall noticing any white exhaust indicating I was burning coolant, but I do remember smelling coolant once, on the day the music died! I dont know where it came from but I looked under the sled and noticed the steam from the rear exchanger and looked for leaks under there - found none! By the way Yammiegod where are you goin with the coolant questions?
There aint no way the carbs could have got some crud in them is there? could the floats have somehow gotten out of whack on 2 & 4 carbs?
Just thinking if maybe it runing lean, could have been caused by something other than the jets? fuel pumps? fuel lines from pump/s to 2 & 4 carbs are not kinked or blocked some how? or loose? no holes in the pipes, or leaky exaust connections?
Just though I`d throw a couple thoughts put there, hope you dont mind.
AL P
YAMMIEGOD 3:16
12-14-2005, 09:41 PM
DUDE, JUST GIVING YA ANOTHER THING TO CHECK BECAUSE YOU HAD SAID YOU MADE SEVERAL WOT THROTTLE RUNS. THOUGHT POSSIBLEY YOU HAD COOLANT ISSUES. JUST THROWNING THINGS OUT THERE. NOW, HUGE FACTOR HERE IS RUNNING QUAD PIPES IS JUST A BIG A FACTOR AS RAISEING COMPRESSION UP TO 140 psi. YOU WILL SEE MORE HORSEPOWER GAINS WITH QUADS THAN HIGH COMPRESSION. WHAT YOUR LEFT TO DO IS TAKE JETTING UP TO WHAT PAT TOLD YA, YOU SHOULD BE FINE. 3:16 (tony)
jminor
12-14-2005, 10:44 PM
Sorry for jumping in on IZZ'S thread but I've got quads on mine and the rest of the motor is untouched and I'm running stock jets which I believe are 143's? and so far it looks like its a little fat but nothing to complain about. Does that sound right to you guys? Again sorry Izz, but everyone is reading this so I'm throwing it out there.
Jminor by all means, please ask!
Al,(thanks for the help) Thats my initial thought to! All the carbs looked great though - floats are all at ~ 14mm (not pushing down the spring) and there all in sync (opening the same amount) Now fuel pump was a big suspicion I had as well but its kinda funny that both pumps would go at the same time though? seein how each cylinder that cooked was fed from a seperate pump! I cant rule it out yet (high speed fuel starvation) but Im not betting on it.
I did notice that my exhaust gaskets were a little leaky though when I got her apart! Not the sealing rings part but the actual gasket between the cylinders and the "manifolds" - could this cause a problem?
humm, I`m not real sure what exactly a leaky exaust manifold would do, but it would seam like to me if it was leaking bad enough, it would let more air in? I`m just trying to think of anything else that could posibley be contributing to the problem, i would really hate to hear that it happened again, and it turned out that something else was going on? although hauck has recomemded larger jets to be the correct ones, I would still go over every little posible thing it could be. and even a couple that it "should`nt" be. Like you said, 157s to 160`s does`nt seam like such a big change, that it would cause such major piston damage on only a couple 2/10 of a mile runs? and the damage is on the intake side to boot? It just seams very strange to me. Plus, if them jets are that wrong, why are them two pistons that bad, yet the other two look perfect? it just dont seam right, its like there`s something bieng missed?
RedWhiteandBlue
12-15-2005, 06:41 AM
I don't know if anyone already suggested this and I don't have time to read everything hear but... A bad fuel pump or crank seal on the side that pump draws it's pulse from would be where I would look. Either one will will cause the sled to "run out of fuel" after a few seconds at WOT and melt pistons. Assuming those two cylinders were hooked up to the same pump. Odd melt pattern but just my $.02...Blue
EXACTLY Al, Thats what Im sayin! - Only Im runnin 152.5's not 157's and was recommended to go to 160's - The other 2 cylinders are fine with no piston damage at all They look like they were probably lean but not to the pre deto point! Its like theres one more piece needed to finish the puzzle and I have it in my hand but it wont fit! (if that makes any sense)
Now each cylinder that was bad is fed from a seperate fuel pump and these cylinders (#2 and #4) dont run a pulse line its the 2 cylinders that are good that run the pulse lines to the pumps!?
Heres some more pics
lets try again! Heres the bad pistons still in the cylinders (#2 and #4) Now theres a hole starting into the center of #2 and the middle of #4 is sorta pitted like it was starting to wear in the middle as well!
The other 2 pics are of pistons #1 and #3 (the cylinders that run the pulse lines) from the front side! they look to be in very good shape yet and the middle of the piston top looks fine
Heres the inside of heads with plugs! cylinders 1-2-3-4 from top to bottom
I also wonder does anyone know how much jetting my stock needle valves will support? I mean does there come a point when you can only jet up so much before the stock 1.3 needle valves wont flow enough fuel to feed them? I figured I better find out before I put the 165's in there and get it all together. Please tell me theyll work cause theyre brand new at 23.00 a piece! Although I do have some brand new 1.5's for a 750 if I could swap my 1.3's to my 750, but I dont know if .2 would make much of a differance anyway!
Any thoughts?
twistedmax4
12-15-2005, 09:25 AM
Could it be that the oil injection system needs to be bled. Maybe not sufficent oil mixed with fuel. Just a thought...mike
VMAX80096
12-15-2005, 09:32 AM
Izz, according to your plugs you are super lean....I would still go with the engine got hot in those 2 cylinders...what is the squish like....stock is about 0.078"...what are you at now....what did the guy take off your heads and are they even? All I can tell you is that I'm running the same base gasket, 0.065 squish, airbox gutted, tops open, 800 pipes at 8800 and 155, 152.5,152.5,155 with 91 octance fuel and I can go for a mile and temps get to 1200 to 1250 with temps down to 10F...and with the 750 pipes you can run leaner jetting than with the 800 pipes. Don't have any answers really. Perhaps see if you can borrow someones temp gauges, even a single one and put it on one of the cylinders that went down.
YAMMIEGOD 3:16
12-15-2005, 09:52 AM
IZZ, YOUR RAKING YOU BRAIN OUT DUDE. UNDERSTANDABLE SO WOULD I!! THE MOST INPORTANT PICTURE THAT TELLS ME THE MOST IS THE SHOTS OF PISTON TOPS WITH THE PRE-DETINATION STARTING RIGHT IN THE CENTER. ALSO THE FACT YOU MELTED YOU SPARL PLUG. ALL I NEED TO KNOW. EITHER GO UP ON OCTANE OR GO UP ON JETTING, DUDE YOU WERE EITHER TO LEAN OR BAD GAS. !! AND THIS IS NOT A LUBERCATION PROBLEM BECAUSE YOUR SIDES LOOK FINE. !! 3:16 (tony)
JAMIE
12-15-2005, 11:06 AM
IZZ, WHEN YOU SAID YOU ADDED A CAN OF OCTANE BOOSTER DID YOU PUT THE WHOLE CAN TO YOUR TANK AS IN 500ML ...?
JAMIE
12-15-2005, 11:32 AM
I JUST TOOK THE TIME TO RE-READ ALL OF THE COMMENTS AND IZZ YOU SHOULD ALSO CONSIDER PUTTING THE GUTS BACK INTO YOUR AIRBOX CAUSE I CAN TELL YA THERE IS LITTLE OR NO GAIN WHATSOEVER BY DOING THAT MOD AND THE SIDE AFFECTS THAT FOLLOW OUTWEIGH THE PERFORMANCE GAINS.SUCH AS REALIABILITY...!CAUSE IN REALITY ALL WHAT YOUR DOING IS LEANING OUT ALL OF THE CIRCUITS.
JAMIE
12-15-2005, 11:33 AM
I'M GOING THE FIRST WEEK OF JANUARY ON THE DYNO WITH A V-4 800 WITH PSI'S QUADS,.039" BASE GASKET,CUT HEADS,142-145 COMPRESSION,SHELL GOLD GASOLINE,STOCK AIR BOX,STOCK VENT LINES,WITH 133.3 MAINS AND THE CLIP MOVED DOWN 1 AND I'M ASSUMING THAT I WON'T BE THAT FAR OFF ON THE CARBURATION SET UP.SO FROM STOCK I'VE DOWNJETTED 4 SIZES RICHENED THE NEEDLE ONE AND WE WILL SEE.I WILL POST THE RESULTS WHEN I GET BACK.ALSO I'M AT SEA LEVEL HERE IN CANADA
VMAX80096
12-15-2005, 11:46 AM
Which quads do you have Jamie, with or without internal silencers?
Izz,
I was just thinking about me suggesting the 92 head gasket. I don't think it will work on an 800 due to the larger bore size. Sorry for pointing you in the wrong direction with the gasket.
Ken....:frech32:
JAMIE
12-15-2005, 12:29 PM
I,VE GOT THE EXTERNAL STINGERS PSI'S
JAMIE
12-15-2005, 12:31 PM
NOW I KNOW THERE HAS BEEN DISCUSSION BEFORE ABOUT 750 VERSUS THE 800 MODBLASTER PIPES BUT CAN ANYBODY TELL THE DIFFERENCE BY LOOKING AT THEM...?
the end of the pipe where it dumps into the silencers, will be smaller on the 750 pipes. the 800`s are 1in, and the 750`s are 7/8. IF, I remember correctly.
Jamie, The 750 pipes measure 7/8" ID on the stinger side and the 800's measure 1" (at least Im 95% sure on that) Id get a 2nd before you bet on it though!
Ken, No problem! I wasnt gonna go with a 92 gasket anyway I have an extra 800 gasket that I will split if I decide to go that route.
Ya beat me Al! but at least theres your 2nd Jamie (or 1st) lol!
JAMIE
12-15-2005, 02:46 PM
OK THanks guys but here is another one for ya i got three of the pipes that are 7/8 but the long swooping stinger on the one pipe is 1 inch from the back of the silencer to the exit make sense...?
vmax4rules
12-15-2005, 03:08 PM
I thought the 800 pipes were 1 1/8" vs 7/8 or 1" on the 750's
vmax4rules
12-15-2005, 03:11 PM
OK THanks guys but here is another one for ya i got three of the pipes that are 7/8 but the long swooping stinger on the one pipe is 1 inch from the back of the silencer to the exit make sense...?
The end of the pipe is the place to measure,
I think all PSI quads have one silencer outlet that is larger than the rest.
toydoc
12-16-2005, 12:31 PM
Izz, according to your plugs you are super lean....I would still go with the engine got hot in those 2 cylinders...what is the squish like....stock is about 0.078"...what are you at now....what did the guy take off your heads and are they even? All I can tell you is that I'm running the same base gasket, 0.065 squish, airbox gutted, tops open, 800 pipes at 8800 and 155, 152.5,152.5,155 with 91 octance fuel and I can go for a mile and temps get to 1200 to 1250 with temps down to 10F...and with the 750 pipes you can run leaner jetting than with the 800 pipes. Don't have any answers really. Perhaps see if you can borrow someones temp gauges, even a single one and put it on one of the cylinders that went down.
From looking at the head pics, the squish was cut into. That left a thin flat line. If it's too tight just at that edge it can trap air/fuel mix and cause also a deto problem. You also don't want any sharp edges any place in the head, cutting into the squish (and not recutting the squish) will give you a edge all the way around the inside of the cyl.
Toydoc, are you talking about the step that I had removed?
Post a picture of your head with the gasket in place. That will give some idea of how far into the squish the head was cut. Did you measure the depth of the step before you cut the heads?
Ken, My step had measured differant in differant spots. I believe it ran from like .029 or .028 to .036 or somewhere in there. (this was a quick initial measurement while I was at the machine shop) I didnt record that, although I wish I had now!
The machinist and I had a long discussion on how much to cut the heads. I told him that Tony sent his heads to hauck and they removed his step, he was told .033, another guy on here (cant remember) also reported he called Hauck and they told him that the "power up" involved cutting to the point where you remove the step and no more. The machinist "Jason" shared your POV Ken, on leaving some step to be safe, I ended up telling him to do what he was comfortable with. He said hed measure it more carefully and consider it.
(Hugh, sorry I didnt answer you on this yet either - I forgot) He called me up and said he came up with cutting ~.032 he said - He also said he cut the heads in a manner to try and even out the small amount of the step that he left (so it wasnt so varied depending on where you measured)
So anyway there is a small "step" but very small, you can feel it with your nail - if your paying attention!
MadMax-4
12-17-2005, 07:52 AM
Man that realy realy suck's
What you have is a clasic sighn of predetonation, sum how the timming is off just a bit. My 750 did the same but on 2 cylinders till I found the crank was twisted.
Just my .02
toydoc
12-17-2005, 09:49 AM
IZZ, when I have my heads cut, I get about .019 then it starts to cut into the squish band. I don't think they can be cut much more the .020 without recutting the squish band. If you had .030+ taken off and not recut the squish band, your going to be to tight at the edge. Check your squish and see what you have right at the edge.
OK Toydoc, Im putting the engine together right now. Ill be checking the squish when I get there. Ill use the old head gasket to check it, that way if the squish is too tight Ill still have my new gasket for the "final" assembly.
1 question though for you and Ken, can I remedy this (if its the problem) with another layer of head gasket?
I know it would be the cheap way out, but could I come to the same result by doing this as recuting that step back into the head?
Guys, I assembled the motor and checked squish in several areas, a couple differant ways.
I started by putting a piece of solder through the spark plug hole and checked the intake side and then the exhaust side, I came up with acceptable numbers, edgy, but acceptable (.060+) So I checked all cylinders this way and came back in to report. When I got to the site i decided to search for "squish" and see what the buzz was on safe squish, well it brought up Kens post on the cylinder lift, and since I hadnt seen this new one I decided to read through it. Thank God I did! (awesome post, by the way Ken)
Ken describes checking his squish by removing the head and inserting a piece of solder on top of the piston, directly over the wrist pin, then reinstalling the head and turning the engine over. Iam so glad I read that because it made sense to me, that was the only "accurate" way to check squish - the piston rocks on the wrist pin pretty dramatically if you push back and forth on the intake/exhaust side of the piston while its at TDC with the head off.
So I went back out and cut 4 pieces of solder to fit the tops of the pistons in the cylinders, I taped them on, reinstalled the heads and pulled it over.
when I remeasured the solder squished over the wrist pins I got completely differant results than before .052 - .054.
Now Im not sure but I dont think that would be safe to run pump gas.
Im also not sure why a couple people told me to measure squish by putting solder through the plug hole and measuring the intake and exhaust side - that doesnt stand to reason because your getting exagerated results due to the rocking motion of the piston on the wrist pin when it hits the solder. Putting the solder over the wrist pins (both sides at the same time) is the truest measurement of actual squish!
So anyway I ended up adding another layer of head gasket to add another .009 or so to my total squish. Im hoping this will help solve my detonation problem - Ive also decided on 160 mains and stock clip at this point. My compression is now at ~ 135 - 137 across the board.
Ill be starting it tommorow and bleeding the cooling system again but I would really like to hear opinions on whether or not you believe this (tight squish) couldve or wouldve been the cause of the deto problem? Because to say Im paranoid about running it is a major understatement!!!
I just gotta say in defense of whoever said to check the squish on the intake and exasut side, they must have made a typo, because I`ve always read on here, to measure the squish through the plug hole, but to be sure to position the solder inline/above the wrist pin, and NOT cross ways towards the intake or exaust. the piston will rock forward and back from the intake and exaust sides, but its not going to rock left and right on the wrist pin, enough to really make any differance. so I believe checking the squish through the plug hole, would be fine as long as you positioned the solder directly above the wrist pin.
Or, and this is just me thinking, maybe they meant you could put one peice of solder facing towards the intake, and another towards the exaust at the same time, and that should work?
Reimond
12-19-2005, 12:36 AM
Hey! I notice you have cut your heads? I notice also from pictures that squish diameter is smaller than piston diameter (caused by head cutting)? If it is like this, it will detonate because wave from side of piston go to cylinder wall, not to center. My 0,02.
Al, 3 differant people told me to check squish that way and none of them were off this site. 1 was a guy who races polaris's in town here and the other 2 were people Ive been dealing with at dealerships! So you dont have to defend them anyway because I understood them completly, and thats what they told me to do!
It might work to check the intake and exhaust at the same time but I would still think you'd end up with one side flatter than the other due to the thrust side of the piston on the intake side but I dont know, all I know is I know how to check squish now thanks to this site.
Reimond, yeah the heads were cut .032 but can an extra layer of head gasket remedy this? I think youre mistakin about the squish bein less than the diameter of the piston though, I checked with a piston and it still fits within the circle created by the dome in the head, its a very close fit though! So Im not an expert here on this whole squish thing but I assume youre thinkin that there was so much cut off the head that it cut into the dome and reduced the diameter?
VMAX80096
12-19-2005, 09:30 AM
Izz, I run 65 squish on 91 premium, any less than that and you are flurtin with disaster!....You will still be on the tight enough with another head gasket. If you can get some av gas and mix a gallon with 4 premium just for safety factor....much cheaper than burning down again.
Izz,
I think that you should be looking for another set of heads or talk to Hauck and see if he can recut your domes for you. Did you do a compression test prior to any of your mods, if so what were you getting?
Remember that high compression isn't everything on these motors. You will probably even lose top end and you also get all the fuel octane issues.
I'd also seriously consider non-gutted air boxes and removing your reed spacers. Once you get all the other issues rectified you can test these one at a time. The air boxes are tuned to resonate frequencies and probably give you added torque across the powerband. As far as the reed spacers go I personally don't think that there were any issues with the reed cages obstructing the ports. Also increasing the length of the intake tract may actually reduce your power based on some of the reading that I have done. These modifications could be aggravating other issues that you have.
I don't know what the stock squish is in the 800's but I will guess that it is around .070"? You raised your cylinders roughly .018" (.039 - .021 = .018). And cut your head .032". If the numbers that I have are correct your squish should have ended up at roughly .056" squish. That's too tight in my opinion, it could produce unwanted heat and too much turbulence at the top end. The tightest that I would run on my Vmax-4 would be .065".
Disclaimer - nothing scientific here, it's just an opinion.......:homework:
Ken
Sorry izz, I thought you meant members here told you to check the squish that way. I was just saying that i never seen anyone here say it, but that dont mean that I could`nt have missed it, but anyway, I agree with ya, they told ya wrong.
Now about your squish, could`nt you go to a thicker base gasket and solve the problem? instead of getting new heads ect. For now anyway? I know they make them in a .047, .059, So how about just using a thicker base gasket? just a thought?
Reimond
12-19-2005, 12:09 PM
IZZ, Ok. Marks on pictures gave me wrong info.
Yeah Al I thought of that thicker base gasket after I already ordered the .039 so it was too late.
Ken, my compression prior to starting this project was 132 - 135 across all 4. This was with a single layer of head gasket that I ran for about 800 miles with no problems on super lean jetting 138.8's and #1 needle position 45 pilots, although when I took the motor apart there was very slight erosion on the exhaust side of #3 & 4! but I attributed this to the filthy carbs I found also.
And on top of it all Ive been outside riding it for the past 2-3 hrs playing around. I filled it with 94 premium from Sunoco and mixed it 150:1 with yamalube for some added safety, I rebuilt the motor this time with good used pistons and rings from Pat Hauck - I also copper coated all the gaskets for safety as well.
Like I said I ran it around out here for a couple hrs playing and it ran like it was way fat, very lazy feeling, I thought it was the 160 mains. I finally got comfortable (after repeatedly checking the coolant and plugs which were black and soaked) and decided to try and hit 8000 rpm. I turned into the beanfield and pinned it. The needle made it to 8000 and it was feeling good but by the time it took me to bring my eyes off the tach and look ahead - I lost power! I instantly killed the motor but left the throttle pinned and coasted to a stop. I jumped off and pulled plugs starting with #1 - looked new! #2 a little brown too it but not much #3 brand new #4 - end of the plug is gone! ate right off - looks like a bomb went off inside that cylinder and I wouldnt be surprised if the pistons in a hundred pieces!
So now what?
Anyone near me want to fix this?
KING OF THE LAKE
12-19-2005, 04:06 PM
JUST A QUICK QUESTION IZZ- - YOU STATED YOU HAD VENT LINES RUN TO AIR BOX. ARE THEY RUN DIRECTLY TO THE AIRBOX OR AROUND THEM TO THE AREA UNDER THE AIR INTAKE. THIS MAY BE THE CAUSE FOR RUNNING LEAN ALSO
KING OF THE LAKE
12-19-2005, 04:11 PM
IZZ, I WOULD LOOK AT SLED FOR YOU BUT IT WOULD REQUIRE YOU TO BRING IT TO ME OR AT LEAST PART WAY. I AM FRIENDS WITH PAT HAUCK SO I COULD PREY ON HIM TO HELP FIX IF I COULDNT FIX BUT I AM QUITE POSITIVE I COULD REMIDY YOUR PROBLEMS. I LIVE IN CENTRAL WISCONSIN. LET ME KNOW WHAT YOU THINK. KING OF THE LAKE [BRIAN]
Brian, I just talked to pat about bringing the sled out there as I am driving through wisconsin christmas night on my way to minnesota.
Iam done wrenching on it!
He thinks crankcase airleak or more likely the psi pipes wont work on my 800 - His suspicion is that theyre possibly to restrictive at high rpm. (Jminor good call) He says the heads should be fine and that .032 is fine to cut off an 800 if you go with the .039 base gasket, which I have.
If you have any input on the 750 pipes on an 800 Id appreciate it because he wanted me to contact PSI and get theyre thoughts as well and
tommorow I planned on putting my stock 800 pipes back on.
I was going to then drop it off at Pats on Monday morning to be fixed once and for all.
If your serious about working on it PM me your number and Ill talk to you about the details.
Id have to have it within a week though because Im coming back home the following Mon - Jan 2nd
Izz,
Sorry to hear about your continued troubles. Obviously your compression isn't your problem as it isn't much higher now that it previously was.
I found a post on another site that I thought you would be interested in.
Posted by black1000 - I also had a 95 800 with PSI quads and the increase was 23-26 horse. There was a problem with some of the quads. One of the pipes, I think the far mag side, would burn down the piston because of a stinger in the pipe used to retain heat for pipe temp. Got to hot and would squeak it. Cut the stinger out and i have seen 125mph on the gun.
Here's the link if you want to PM him.
http://www.snowmobilefanatics.com/forum/topic.asp?TOPIC_ID=28796&whichpage=1
It's the second post from the bottom.....it's right above some guy named racer7x who posted a link to Vmax4.com :gtyof:
Ken
racer7x
12-19-2005, 07:06 PM
Izz,
Sorry to hear about your continued troubles. Obviously your compression isn't your problem as it isn't much higher now that it previously was.
I found a post on another site that I thought you would be interested in.
Posted by black1000 - I also had a 95 800 with PSI quads and the increase was 23-26 horse. There was a problem with some of the quads. One of the pipes, I think the far mag side, would burn down the piston because of a stinger in the pipe used to retain heat for pipe temp. Got to hot and would squeak it. Cut the stinger out and i have seen 125mph on the gun.
Here's the link if you want to PM him, second post from the bottom.....right above some guy named racer7x who posted a link to Vmax4.com:gtyof:
http://www.snowmobilefanatics.com/forum/topic.asp?TOPIC_ID=28796&whichpage=1
Ken
:banana_1::banana_1::banana_1::banana_1:
Ken, your the man! Ill look into that.
jminor
12-19-2005, 07:26 PM
Guys the word around here is that the trailblasters with the internal stingers would run too hot, that could play into Ken's theory. Izz your throwing alot of squish which equals alot more air pushing out pipes with smaller diameters than the ones originally designed for that motor. Sell those 750 pipes and be the first in line for King Of The Lakes setup!! I notice my mag side plug very slightly lighter than the rest for whatever thats worth but I thought that is a typical situation with most motors.
Well I cant get logged into that SNOWMOBILE FANATICS website for whatever reason and I dont want to take the time to figure out why. So Brian whats your take on that - Kens qoute from black1000 - I have the 750 maxblasters by the way on my 800 - yvx4-04-02 do you think that could be backing the system up? especially considering the other mods Ive got goin? and also before I forget heres a pic of my vent lines
Well I cant get logged into that SNOWMOBILE FANATICS website for whatever reason and I dont want to take the time to figure out why.
I posted and sent him an email.
Black1000
12-20-2005, 07:09 AM
IZZ:
I was asked to reply by someone on this forum. The 750 PSI pipes are very dangerous as you are finding out on the 800's. You should try and outfit yoursd with 800 quads. The 750's are smaller in the outlet side of the pipes and the one in the far mag side has a stinger in the end of the pipe that streches back up the pipe and inch or two. This was to retain heat in the pipe and give more consistant power. It runs too hot. You have to cut the stinger out and jet a little fat as it will definitly lean out while your squeezing it.
I speak from experience. I had a 93 and then a 95. Traded quads and would squeak #4 all the time. Bought 800 quads and had no problems. Cut the old ones apart and found it. Also run EGT sensors and you will see quickly.
Hope this is of some use. By the way wish I knew about this site when I had mine.
ghodder
12-20-2005, 11:05 AM
Great thread guys ... excellent information here for the amature tuner like myself.
Jminor, I get the same plug reading on my mag side cylinder ... always lighter than the rest. Considering that pipe is much shorter than the rest .... Black1000's post has got me thinking.
Izz, can you measure your 750 PSI quads and post a couple of pics so we can all identify which sets we've purchased. I'd like to know for sure that I have the 800 quads, becuase after reading all these posts I'm not 100% sure. Other posts have indicated a 1" outlet measurement for the 800 Quads.
For those of us vented to the airbox, what is the best setup?
I was setup just like IZZ but after a burndown last year I felt that maybe 2 vent lines into 1 outlet was too restrictive and actually caused a lean condition on long wot runs, so I switched to four direct lines vented into the top of the airboxes.
YAMMIEGOD 3:16
12-20-2005, 11:42 AM
BLACK1000 DUDE NOW THATS A GREAT POINT. VERY WELL GOOD BE PROBLEM. 3:16 (tony)
VMAX80096
12-20-2005, 01:13 PM
Izz, I have a buddy who ran 750 pipes on 750 FIII cylinders, then went to 800 pipes and had to then jet up a size, never burnt down with the 750 pipes. I don't think a stock 800 would flow anymore or as much air as 750 FIII cylinders flow. Did you check if you are out of phase?
I thought the 800 pipes were 1 1/8" vs 7/8 or 1" on the 750's
ghodder.
Vmax4rules is absolutly correct!!!!
I`m the moron that keeps saying the 800 pipes are 1inch. i dont know why i keep saying that, when infact they are 1 1/8. I just re measured mine not more than 2 minutes ago, and they are 1 1/8 at the end of the pipe where it goes into the stinger. sorry about confusing things. AL P
One thing I did want to say though, is my mag/clutch end pipe (number 1) is the longest. the shortest is the one on the pull rope/chaincase side/end (number 4)
jminor
12-20-2005, 01:38 PM
AL P your mag is on the pull side!
AL P your mag is on the pull side!
are we talking about a vmax 4?
jminor
12-20-2005, 01:51 PM
OH-OH I might have put my foot in mouth here I've never been into my V4 mag but I thought they all were opposite of clutch side. If I am wrong someone correct me and AL P my apologies!!
Its definantly on the clutch side, no big deal, I get confused sometimes too with it. Every other snowmobile motor that I know of, has the mag opisite of the clutch. I was trippin when i first discovered it next to the clutch when I first got my vmax 4.
jminor
12-20-2005, 03:00 PM
UHHH DUH ALUMINUM CASTING WITH WIRE COMING OUT BEHIND CLUTCH, I'LL BE OKAY!!!!!
Black1000
12-20-2005, 03:35 PM
Actually the pipes all have the stinger in them. Sorry its been a while. If you are going to try this kind of performance on a 2 stroke you MUST keep an eye of the exhaust gas temperature. Cutting out hte stingers will drop the temp in those pipes about 100deg. I cant remember the exact temp of melt down but its somewhere around 1400. I believe safe was 1300- 1360. After that money.
Skinner
12-20-2005, 04:07 PM
Actually the pipes all have the stinger in them. Sorry its been a while. If you are going to try this kind of performance on a 2 stroke you MUST keep an eye of the exhaust gas temperature. Cutting out hte stingers will drop the temp in those pipes about 100deg. I cant remember the exact temp of melt down but its somewhere around 1400. I believe safe was 1300- 1360. After that money.
It depends on where you are reading the temperature in the pipe. Somewhere in between the head flange and the first bend should be a sweet spot for temp. The cost of a four window digitron is about $500.00. Less than the cost of one thermo nuclear meltdown. Would not run a performance motor without it. Takes away all guessing. Santa should be here next week, put one on the list. Like Black says; YOU MUST KEEP AN EYE ON THE EXHAUST GAS TEMP
Skinner
I can see all the sides of this - I understand how these pipes could be to restrictive for the mods Ive done - but I also dont see how they could be any more restrictive than the stock 4 into 2 exhaust!
Maybe I shouldnt have my vents in airbox - but why did #4 only burn down and not all of them (unless they were on theyre way - the plugs did look super lean after #4 melted)
If I had a crankcase airleak why did the plugs look so black and oily all the way up to my WOT run - wouldnt an airleak affect the burn at all rpms?
Heres more pics- 1 of the sled (at least shes pretty)
3 of the pipes - hopefully youll be able to tell what they are
1 of the plug from #4 after a few seconds at 8000rpm
Oh and if you look close in the 1st pic of the pipes under the rad you can see hose clamps around the pipes - these block off 3/16" holes in the pipes that the previous owner mustve used for probes.
And believe me Skinner I want a set BAD! I was almost there on a set of redlines but these burn downs have set me back (I know I shouldnt have even moved it till I had them) Fortunatly I got through the 1st meltdown pretty easy with the help of Mr. Hauck and Im hopin this one dont set me back to much further. (Im already tryin to think of a way to explain to the kids why santas not comin this year) lol!
Actually the pipes all have the stinger in them. .
Is this just the 750 pipes your talking about? because i believe the "modblasters" have no internal stingers in any of the pipes, atleast I know the 800s modblasters dont. or are thye the stage 2? either way, my pipes have no internal stingers, so what pipes do i have? modblasters/stage 2, or are they the same thing?
thanks
Black1000
12-20-2005, 06:12 PM
The mod blasters did not. They were for all out racing. As free flowing as you wanted for full race. I am talking about the trail pipes. The stock y pipes and pipes were less restictive because of the fatter pipes held the pressure correctly. I put my 800 stock y pipes and pipes on my 750 and picked up 9 horse. Put your EGT sensors in about an inch or so from the flanges and you will be fine.
I repeat IF YOUR GOING TO PLAY THE HORSE POWER GAME DO IT RIGHT THE FIRST TIME. It will cost you less in the long run.
Exhaust temp is critical when doing performance mods in anything let alone a temprimental 2 stroke. 50 degrees could mean the difference between shut down and scattering a motor.
Black1000
12-20-2005, 06:14 PM
Sorry, and IZZ the guy you bought the pipes off of was doing correctly. Thats where the sensors go.
Snowmax93
12-20-2005, 06:29 PM
IZZ, just to settle my mind on this alternate piston burn melee , you have of course checked the fuel line routing making sure they're connected to the pumps correctly ? This will eliminate the weak pump theory for leanburn .
As far as I can tell arent my pipes the exrenal stinger version? or could they hve some stingers inside as well? I believe these pipes to be made post 94 since the install sheet I got with them says:
yvx4-04-02
92 - 94 yamaha Vmax 4 stage ll mod quad pipes
Snowmax93, my fuel lines are hooked up the way theyre supposed to be with the pump on the recoil side feeding #3 & #4 and clutch side pump feeding #1 & #2 - So yeah I guess Ive pretty much ruled that out since my 1st burn down was #2 & #4 (1 cylinder from each pump)
stick a coat hanger in the pipes and feel around, you should be able to tell wether thiers any stingers in there? so rumor has it anyway.
AL P
Are you 100% positive these hose clamps on the pipes are not leaking? is there anything under the clamps, or are they just covering the holes by them selves?
SRV540
12-20-2005, 07:27 PM
yeah I would have those holes welded closed if they are not being used.:xmas-smil
Are you 100% positive these hose clamps on the pipes are not leaking? is there anything under the clamps, or are they just covering the holes by them selves?
JAMIE
12-20-2005, 07:44 PM
izz, you have the modblasters i see the silencers i believe the stockblasters have a closed cone on the end and the stinger exits further up the pipe.
Skinner
12-20-2005, 08:45 PM
Izz
The bands on your pipes to cover the holes is close to where we have ours. I can get you a dimension that we use if you like. Spents hours with the digitron tech, he runs small bore dragsleds too. No fixed science on egt sensor placement. Like I said, there is a sweet spot in there. Might never really find it, however, if you get it outboard of the piston, the temp gets higher for a ways before it starts to cool off. Lets say you are 4" from the piston with the egt and you show 1300 degrees on the TV, your Ok at the piston. 4 window digitrons are
hard to find used. I need to order two more, if anyone is really interested, I might be able to get a reduced cost on volume
Skinner
Hugh, I dont understand the "out of phase" thing? Something to do with timing I suppose. I havent done anything to it, so I cant imagine something happened, but I dont know.
Anyway I just decided that I dont want to keep playing this game - theres something goin on that I dont have the expertise to fix at this point. I mean I could always get new heads and put it back to stock and have old reliable again, but Im still convinced it can be made to work reliably with the pipes and power up mods - Ive crossed the point of no return!
Its just going to take the hand of someone who has experience and knowledge of tweaking 2 strokes and Vmax4's specifically - Otherwise Im gonna keep makin it worse before I finally make it better. (More $)
Ive been in communication with King of the lake (Brian) - The guy whos gonna make some quad pipes for us that should perform as well or better than the PSI's - Hes agreed to take a look at my sled. Ill be dropping it off to him Christmas night.
Black1000
12-21-2005, 08:19 AM
The out of phase thing refers to the crank shaft twistind and getting out of time. Never heard of that problem on the 95 and up. Was a bit of a situation on 92-94. Unless you had severe and catasrophic failure not something I would give to much thought.
VMAX80096
12-21-2005, 08:22 AM
Izz, that is probably your best bet. Out of phase is when your crank twists, and causes the piston to come to top dead center when it shouldn't be, too soon or to late....get 2 pencils and find when 2 pistons come to top at the same time...they should be identical, and then the other 2 should...the pencils go in the cylinders and are your top dead center guides. You could go back to the stock pipes and see how it runs but if it isn't a pipe issure you will burn down again..cylinders won't handle many of those. Take it to Brian and let him have a look...sorry don't have any other advise.
Two pistons would never come up TDC at the same time, unless he 180`d the crank. I believe he is still at 90. however, when piston one (nearest the cutch) is at TDC, number two should be at BDC, and numbers 3 & 4 should be even at half stroke.
but considering the mad is on the clutch end of the crank, even if the crank twisted, (asumming it happened in the middle) it would`nt effect number 1 or 2 cylinders. so he would`nt be having a problem with that number 2 cylinder.
at any rate, I highly doubt it would be the crank anyway.
AL P
Al you are right on the money and here's the photo to backup your post.
If someone wanted to check for twist they would probably want to put a degree wheel on the recoil side of the crank and use a dial gauge on the cylinders to make sure that TDC is at 90 degrees for each cylinder.
Thanks ken.
I just went back and edited my last post, because i said he would`nt be having a problem with that "number one cylinder" but I meant that number TWO cylinder, but either way, its the same idea.
Now just to point one other thing out, although that picture shows two pistons even, they are actually moveing in opisite directions when they line up like that, so depending on which way you rotate the crank, one will go down, and the other will come up. just wanted to point that out, so it was`nt mistaken that they could both come up to TDC at the same time.
Thanks again for the picture ken!
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