crank reliability & crank alignment questions???

[jminor]

so when you start to pound the torque to these things on the grass, how are these bottom ends holding up?

[YAMMIEGOD 3:16]

DUDE, NEVER HAD A PROBLEM WITH EITHER OF MY 800,s ! 95 ON GRASS AND 96 ON ICE AND SOON TAR. !! 3:16 (tony)

[jminor]

what kind of miles are on them?

[Reimond]

I believe you will be fine with 800 crank but with -92 750 there is trouble... Mine twist on loose snow.

[vmax4rules]

As far as I have read, the 1992/94's needed the crank welded - 1995/97's did not.

[YAMMIEGOD 3:16]

CRANK WELD ON 750 ONLY IF SPUN OVER 9000. 95/97 NO WELD NEEDED, SUPOSELY GOOD TO 10,000. 3:16 (tony)

[Skinner]

From what I remember back in the day on the 750's, Yamaha recommended welding the crank even if it was a simple mod such as putting on a set of quad pipes. This was no longer necessary when they introduced the 800's.

[jminor]

I know all that I was wondering how these things were holding up for the guys that are racing them and how many miles are being put on them in these extreme conditions.

[YAMMIEGOD 3:16]

JOSH, DON,T KNOW WHAT YOUR ASKING. lol !! I GUESS IF YOUR RUNNING UNDER 9000, THAT REALLY WOULD NOT BE EXTREME !! NOW IF YOUR RUNNING 10,200 AND FIRING AT 180, NOW THATS EXTREME !! AGAIN MY GUESS THESE CRANKS ARE ALL TRUED AND WELDED. !! ALL DEPEND ON WHAT RPM YOUR RUNNING AT !! 3:16 (tony)

[jminor]

Tony what I mean is what is the predicted time of failure for these bottom ends? My bottom end has around 8000 miles on it and now its going to be torqued to death on the potato fields of Jacobeys!! Take a skidoo for example you know around 6000 miles you will be completely redoing that bottom end. Is there a common mileage where these show enough fatigue that they require a tear down? BTW I will be spinning 8750 or so...:fishing: !!!!

[vmax4rules]

Here is what I can tell you from my experiences:

I ran my 1992 Vmax-4 750 for more than 11,000 miles of hard trail use with the only non stock engine
component being the PSI 8350 rpm pipes with no issues, this engine is still alive in one of my buds ex race sleds.
Also I have put more than 9,000 miles on the 800cc Vmax-4 engine that replaced the above 750,
again the only non stock engine component was the PSI 8800 rpm pipes - this sled still runs like a champ!


Hope this helps.

[YAMMIEGOD 3:16]

LOOK AT THE MILES ON RULES VMAX4,s. LOOK BEING YOURS IS A 800, I DON,T FORSEE A PROBLEM FOR YA. THAN ON THE OTHER HAND, YOU GOT THE BEST CRANK, YOUR NOT RUNNING ALOT OF RPM, AND I HAVE NO IDEA WHAT THE TIMELINE FOR FAILURE IS. I GUESS IF YOUR RACING THAT CAN BE ANYTIME lol !! 3:16 (tony)

[Skinner]

I know all that I was wondering how these things were holding up for the guys that are racing them and how many miles are being put on them in these extreme conditions.

If ya know all that then whats the question? Its a loaded question to start with. How many miles will my crank last? Hmmmm, how hard was it ridden? Did ya use penzoil? Was it run lean most of its life? And on and on. It will last until it breaks, so run it and see what happens. Throw the juice to a weak bottom end and it will be like throwing a hand grenade under the hood. Don't worry about "blowin yer crank",,,,,,Josh.....LOL... I have a spare in case ya need it

[jminor]

Thank you Skinner for the input. I know there are no guarantees, I was merely making conversation and seeing if there was any patterns out there. I'll shut up now, take my toys and go home.:Flush:

[YAMMIEGOD 3:16]

HEY, WHEN YOU '' BLOW YOUR CRANK '' AT JACOBEYS, YOU CAN SAY , SEE THIS IS WHAT I WAS ASKING !!!! lol. THAN I,LL SAY NO !!! '' THATS RACING '' 3:16 (tony)

[jminor]

As long as you don't blow a nut when I scream past you!!!! LOL! Sorry I had to do it and will probably eat my words for saying it too! Hey, I've got to survive a couple of races before jacobeys by then I may just be a spectator, who knows, I do understand that racing is not the best thing for your hardware that much is obvious!

[YAMMIEGOD 3:16]

HEY, WON,T BE THE FIRST TIME A BLOW A NUT !! lol. 3:16 (tony)

[jminor]

LOL!! I guess to clarify the original question even more was that to launch these on the dirt with studs that are about .5" or more over the lug and wicked gearing is going to put alot more force to the bottom end than anytime on a snowy surface would IMO so I wondered if there was any common problems amongst grass racers. That is all. When is Jacobeys again? Also, are there any other events in the NY area that would be worth me trying my luck at?

[Skinner]

ROTFLMAO
This craps just to much!!!!!!!!!!! :clap:

[YAMMIEGOD 3:16]

JACOBEYS IS FIRST SATURDAY IN NOVEMBER. ALOT OF RACES IN NY, I,LL POST DATES AS WE GET CLOSER. JOSH, YOU COME OUT AT 5000 ON CLAY WITH WICKED GEARING , I WOULD WORRIE ABOUT CHAINCASE MORE THAN CRANKSHAFT. 3:16 (tony)

[jminor]

great point.

[AL P]

Yeah as I`ve been reading this thread, I`ve been thinking that I`d be worried about my chain/case and my drive shaft probley just as much if not more then my lower end, not that the lower end would`nt be more costly, but it just seams like the drive shaft and or the chain/case would really be under alot of stress!

AL P

[Maha]

I was reading this and feel special, I run my 92 ( 750 ) with a RPC 840 BB kit, RPC Stealth quads, Digial 90 degree CDI with the 7900-10,000 rpm chip in snow and have had NO problems in snow with my stock crank. Now I don't race on grass or dirt and have no studs but my concerns would be the chain or drive shaft first. My avatar speaks for itself......

[als92vmax4]

how hard is it to weld a crank? anybody have any instructions or pics how to?

[AL P]

I dont think it would be hard at all for a very good weldor, with the right equiptment.
but, you`d want to be absolutly 100% positive it was lined up, and not out of whack at all, before ya welded it.

I`m pretty sure Racer7x posted a pic recently of one that has been welded, I`ll look around later and see If I can find it.

AL P

[Skinner]

I dont think it would be hard at all for a very good weldor, with the right equiptment.
but, you`d want to be absolutly 100% positive it was lined up, and not out of whack at all, before ya welded it.

I`m pretty sure Racer7x posted a pic recently of one that has been welded, I`ll look around later and see If I can find it.

AL P

Al, there are instructions on the Bender sheet posted on the same thread

[racerrob]

Okay, go easy on me here for the following "dumb question"
Mom told me as a kid that there were no "dumb questions", hope I dont proove her wrong here!!:frech32:

I plan to get my crank welded during my upcoming tear down-updates & conversion in the next few weeks.

Are there markings on the end of the cranks that show the gears have not "slipped" a bit over the years?

Is that a possiblity that the crank could "twist" a little, as a few degrees from the factory setting, or has the pattern been if its gonna "twist" it would be a big obvious "twist" and ya would know it by how the sled is running now??

Thx for the input

Rob

[hontri]

Okay, go easy on me here for the following "dumb question"
Mom told me as a kid that there were no "dumb questions", hope I dont proove her wrong here!!:frech32:

I plan to get my crank welded during my upcoming tear down-updates & conversion in the next few weeks.

Are there markings on the end of the cranks that show the gears have not "slipped" a bit over the years?

Is that a possiblity that the crank could "twist" a little, as a few degrees from the factory setting, or has the pattern been if its gonna "twist" it would be a big obvious "twist" and ya would know it by how the sled is running now??

Thx for the input

Rob

Good question :4fzfk2: I would like to know the answer to that also!!!!!!!!!!

[AL P]

To the best of my knowledge, there are no markings showing where to locate the gear on the crank. only markings I know of, is the dots on the gears themselve`s (750), and the holes on the 800`s gears., that you use to align the two crank halves. could be wrong though?? would`nt be the first time, thats for sure.. LOL

Here`s a pic of my 800 crank when I had it apart, and I did`nt see any kind of markings?

http://img169.imageshack.us/img169/1588/vmax4crankdp2.jpg

AL P

[hontri]

AL P...Thanks for confirming my suspicions.I could not find any reference marks on my crank either, except for the ones you mentioned.:2dontknow
So...how do you check to see if is right? Lot of brain power on this forum beyond my capabilities....someone must know:bowdown: .

[racerrob]

Hey guys, glad I asked the question!!!! Dont fee too dumb right now!!:frech32:

Maybe, we need to put this out as a new, renamed post so that we get the real "brain trust" of the Vmax 4 guru's to wiegh in on this??

I might be missing something here, but I would think that it would be really critical to performance, reliability etc to know how the crank & pistons are to be aligned, BEFORE ya weld them!!

How do we get this to be a new "different named" post w/o redoing the whole thing?

Al, got any ideas???:2dontknow
Rob

[racer7x]

I can change the name of the thread, what would you like it to be???????

[racerrob]

How about crank alignment questions???

Hey Dean, have you done this??

Thx Rob

[racer7x]

NO, I haven't yet.. Possibly next year, unless I'm to busy working on my 96..

[AL P]

when i first got my vmax4, i had read about crant twist, but did`nt know it was the 750`s that it usually happens to, anyway, what i did, was get cylinder one (nearest the clutch) at TDC, then checked to see if cylinder two was at BDC, and cylinders three and four were at half stroke.
I just did the test with a straw in the plug hole, and measured it that way, figuring if it was off, hopefully it would be off enough that this would show it, and if this did`nt, it was probley alright.
but...to check to see if it is infact DEAD ON, I`d say a TDC dial gauge, and degree wheel would do the trick..
you could locate TDC with your dial gauge, then line up some kind of pointer to your degree wheel, and set the wheel to 0 degree, then rotate the crank 90 degree at a time, and check to see if the next cylinder in the firing order had its piston at TDC, and so on..
the plan here, would be to bolt the degree wheel onto the clutch and then take a lengh of coat hanger or whatever you can come up with to make a pointer..and point it at 0 degree when you get piston one (nearest the clutch) at TDC, and go from there, piston one should be your base, cause its least likely to be off..
just be sure to rotate the clutch in its normal direction of travel, and if you pass your mark, back up plenty, then move forward again.
reason bieng, the clutch PTO shaft, seams to have a little bit of play (where the bears meet in the case`s), so if ya aint carefull, that could throw off your readings.
AL P

[hontri]

AL P ...I thought of what you are talking about but..... what if you find out the crank is a little bit out of phase. Then what...take engine apart press off the gear and reinstall...how much?Put it all back together and check it again! I can see this being very time consuming.I suppose you could take measurements when you move the gear and see how that affects tdc and eventually get it dialed in. There must be an easier way!! But maybe not.

[racerrob]

Hontri, :agree:

Exactly what I was thinking!!!

You would think that there is some method of "indicating" where the piston/crank/gear relationship is supposed to be.You are right, a guy could go through a lot of time & effort & miss the right setting.

While I have no problem gettin in there to do this, I want to make DAMN sure I am doing it right, especially when we go to weld it. That makes it real permanent!!! Be a bitch to undo that !!!:cussing:

Nothing is said in the service manual about what to look for in this area. Just the 2 punch marks as Al talked about when your reassembling the 2 halves back together.

Well, maybe ya dont have to worry about being a few degrees off, or when the gears/crank "spin", its a BIG move & then ya worry ??.:2dontknow

Does anyone know if this a heated "sweat fit" or "shrink fit" at the factory?
Am guessing this is how these were assembled when new.

Rob

[AL P]

you got me? if I found it to be off, I`d probley just send it out to a shop that could align it, and weld it. I`m not sure if i`d try it myself.
its all about equiptment, which I dont really have for that kind of work, if a shop knew what the crank was suppose to be set at (degree/firing order/crank rotation direction), they`d have equiptment they can use, to get it just right the first time, where as with the crank out of the motor, I`d just have to back yard it, and hope like hell I got it, cause I cant think of a way off hand right now, without the proper equiptment, to be sure it was DEAD on, I`m sure I could get it damn close, but dead on???? I would`nt wanna bet on bieng able to pull that off. myself anyway.
AL P

[noink]

hi guys
when i was racing yamaha tz750s and 373 and 250s it was common to teardown the engine and inspect it and the first thing was alway cranks
we never welded them due to the damage caused when pressing them apart to change bearings
so we watched them like crazy and never buzzed them
but when it did move we would take them to the shop for aligning...
actually it was bazaar to watch them true the cranks, violent abuse is more like it !!!
after checking on v blocks with dials then comes the tweaking...
a lead plate 1 inch thick and a 10 pound lead mallet and some serious blows on the counter weights to true it up, back to the dials , more smacks and thats it your done, true crank ready to bo battle again!!!

but let me tell you the first time i saw this done i grabbed the mallet from the guy and threatened to beat on him but i eventually came back after finding out he was the guy yamaha only reccomends

i never saw a crank failure from this guy or others using his services

in a word dont do this yourself it is a black art !!!

[hontri]

Noink..I've also seen that done and it is brutal to watch!! That does true up the crank but it still does not explain ..at least to this simple mind ...where you place the gears on each crank half so they are in synch?

[silver92]

I can give you some input on yur bootm end, I have raced cosdra for 9 years on grass.
Life wil totally depend on your dirt intake, If running no filters or box don't expect more than a year or two on grass, with air boxes it is a liittl better but not much. I would reccomend K&n's should be able to run 5 years or more. I could also help you with set up for this.
Used to run a 96 800 in improved stock.

[the Wolfman]

dial indicator.....assembled...it's the only way