Exhaust Identification and Intake Questions With Pics.

[Stanford]

Hey all, I'm new here. I ride a V-max 800 that I need some help with. It has some sort of Pipes that I was told are aftermarket by a dealer I showed them to. I am not sure the brand though. Can anyone identify these as OEM or Aftermarket and if so what Brand? They are LOUD. I am talking Extremely loud, like it can be heard 1/2 mile away. I think the silencer needs re-packed. So I am going to cut it open and put some new packing in there, then weld it back up with my welder. Pictures of the pipes and silencer are below.

Also for my other question. It runs very rich and stays really cool. I just wonder instead of messing with the Carbs that I could modify the Intakes a little to let more air in and lean it out some. I come from Turbo cars and am knowledgeable with them. I don't know much about 2 strokes, carbs, and Snowmobiles though. Anyway my idea is this. There are 2 seperate Black Intake boxes that the carbs suck air from. They have small rectangle shape inlets that are pretty small. There is quite a bit of material I could grind away to open up the intake path. I would leave the Foam in the Hood where it pulls the air through. I just want to enlarge these inlets to allow more air into the engine. Is this a common mod? What other cheap/free mods can be done to these 800's to improve performance? I mainly just want to lean it out a little and focus on the intakes.
http://gallery.indystars.org/albums/Stanfords-album/Mvc_007f.jpg

http://gallery.indystars.org/albums/Stanfords-album/Mvc_008f.jpg

Thanks and Regards,

[lokn4sno]

The pipes appear to be stock (OEM) the silencer looks aftermarket. Also the stock silencer has no packing, all baffles.

Be careful with airbox mods!! In my opinion I would do some plug checks, and maybe start with jetting down -- if possible...

[mtbombsqd]

AAEN has silencers listed on their web site, repackable, that would cut down on the noise. Somebody on this site will know those pipes, they look somewhat like what my stock 750 pipes looked like, I've never seen the stock 800 pipes so I can't help there. Personally I wouldn't cut into the intake box, I would seal it up better and make it pull in only outside air, it cheats alot and suck in air from under the hood which hurts the performance.

[Stanford]

I see well hopefully they are at least the stock 800 pipes. I would hate for them to be from a smaller motor. Everytime I swap the plugs they are black as can be, which tells me it is super rich. There are foam gaskets on each air box that have a nice imprint where the hood presses on them. So I would assume it is getting a decent seal. I can always use new thicker foam. I'll check some web sites out and see what I can find for new silencers and/or pipes. I'd like to get a few more Hp out of it. I looked through a Dennis Kirk and came up with literally nothing for the 800 Model. I will try to read up on Carbs but I don't know about Jets yet, once I do I will look into Jetting it down.

[3ft]

You have come to the right place...although I may not be able to help much....their are many people here that know these sleds in side and out. When you saythe plugs are black...are you fouling them out? I don't want to boar you with things you may already know, But a carb has 3 circuts, 1st.. idle(and just off idle) is your pilot jet..the needle jet will run the midrange, and the main jet is 3/4 to wot. The reason I ask before you jet down your main jet, I would take it to a lake and run it at wot (after warm up) for a good long run....with the throttle still at wot, hit the kill switch and bring the beast to a safe stop, pull the plugs and read them. With afternarket pipe or silencers, you really want to be careful about leaning it out to much, It could be a needle clip position that you may wat to change as the mid-range is rich(if thats what you find) Droping the clip position(raising the needle) will richen it up...raising your clip position(lowing the needle) will lean it out. I am not telling you to do any thing...If it was me I would want to check the plugs at a few diffent trottle positions and see what it can tell you. I am by no means any expert but Think this might help you. Good luck, have fun with the new beast. 3ft

[Stanford]

Well that helps, like I said I am a novus with Carbs. If it was a Turbo 4 Stroke EFI I would be fine, however NA 2 Stroke Carbed is not my area of expertise. Yeah it will eventually foul them out and not start. I couldn't tell you at what RPM though. I did a lot of Mid-Range riding this weekend with a few WOT runs. I'll pull them tonight and see how they look. It was running pretty good so I didn't even bother after my ride.

[Exciter570]

Those definately look to be stock pipes, however it must be a aftermarket silencer because the stocker would not be very loud. I may have a nice set of Bender Quad pipes for sale in the spring, save up a few hundred and you can bolt on 18hp!

[Stanford]

Ok so the consesus is I have stock pipes with an aftermarket silencer. Fair enough. Would the silencer have gained me any power? I'll try to get a better pic to see if someone can identify the brand.

As for your pipes, yeah I'd love to upgrade to them. Are there even any companys that make new ones anymore? It seems you have to get them second hand. Whats the average cost for a set of pipes?

[Exciter570]

Aaen performance does, $925!!! ouch! You should be able to pick up a used set such as Bender's or Aaen's for $350-$450.

[Stanford]

I'd never spend a grand on pipes, that is nuts. Heck the Sled was only 1500.00. I am not sure what they go for but thats what we got it for a few years ago, it has 2700 miles. $350-$450 is much more in my price range. I'll probably stick with stock for this winter though. Are there any free or cheap mods that can be done to speed these up? Can those little Y-pipes in the exhaust be ported for any better flow? Is there anything can be done to the intake to gain some more power?

[Ike]

To help some top speed performance, check this out. Easy to do.

http://www.vmax4.com/tech1.htm and

http://www.vmax4.com/techmain.htm

Route the vent tubes to the upper level of the airbox. It helps by lowering the underhood pressure = carbs don´t go rich near top speed = more mph.

Do a search about the things you can do to a 800 or just look around. There are tons of good info here. Cylinder lift, cut heads, quad pipes etc. I´ll try to find some too for you.

Try the YammieGod´s setup. It´ll wake your sled really up! And most of all ask if you need to. There are no stupid questions. We all are here to learn something new about our sleds.

Ike

[Stanford]

Thanks for the links. I looked at the Tech page but hadn't noticed the Vent tube article. I read the whole thing and don't really get it. It also didn't have pics showing where they are. I'll keep searching around and see what I can find.

[Ike]

When going fast, the Vmax4 creates overpressure under the hood. It´s because of it´s desing. This overpressure makes the carbs to go richer = loss of hp. When the vent tubes are routed to the airbox or to the handlebars, carbs don´t get richer because the overpressure is now avoided.

I think that is it in short. Someone else?

Ike

[Ken]

The pipes are stock, you'd have to measure the Y and the expansion chamber inlet diameter to determine if they are 750 or 800 pipes.

By the picture and my finely tuned eye I would say that they are 800 pipes.

I'd say that the silencer is homemade, it uses a stock outlet pipe. There is usually no HP gain from the silencer and quite possibly a lose of HP depending on the construction of it. You can probably find a stock can at a reasonable price from one of the site members if you are interested in one.

If your running rich then you should check and make sure that you choke is adjusted properly and that one or all of the choke plungers aren't partially open or defective.

I'd suggest pulling and cleaning the carbs, and checking to see what's in them for jetting. Check the needle and seats, choke plungers, carb sync, etc.

You're probably going to loose performance if you start screwing with the air boxes.

If the engine is running cold then check and see if the thermostat is present or if it's stuck open.

The Y-pipes are basically stamped sheet metal, not much room for porting/grinding.

I don't understand the logic behind wanting to modify something that you feel isn't running properly in the first place. :banghead:

If there is something wrong with the sled then fix the problem, there is lots of HP to be gained by having something that runs properly.


Ken

[Stanford]

Ike, yeah now I see. I am not sure where these are though. Anyone have a pic with them circled or Highlighted?

Ken, Thanks a bunch. Yeah I won't be doing any modding until it is running 100%, I always tell people the same thing when it comes to cars. So theres no reason I shouldn't apply it here.

I will pull off the pipes to clean them up a bit and measure to see exactly what I've got. As for the Silencer, does anyone have any reccomendations for an inexpensive new one? I don't want to lose any power though, so if it has to be loud thats fine. I just don't like the idea of it being Homemade as it sits. It could be hurting power for all I know.

I am not a Carb expert but I'll look into the choke and see what I can figure out. It appears to work fine though because when I flip it on and off the engine reacts as it should.

I'll post some pics of my plugs tonight so you all can have a look and tell me what you think. I have the Yamaha Factory Manual for the 800, I'll have to look through it tonight and see if it shows/explians how to check/swap the carb jets. As I have not a clue right now, but I will learn quick.

Thanks for the thermostat reccomendation, I will check that also. I am not sure of the standard operating temps of these but I would think the radiator hoses would have been a little hotter than they were after an hour ride. I could easily hold them with my hand and not get burned. It was maybe 80-90 Degrees. I'd think they should run way hotter than that.

You guys have been a great help so far, Thanks.

[Ken]

I am not a Carb expert but I'll look into the choke and see what I can figure out. It appears to work fine though because when I flip it on and off the engine reacts as it should.

The choke uses 4 enrichment plungers, if the cable doesn't have any free play in it the plungers can be held open slightly causing a rich condition. The seat of the plunger can also be damaged (unlikely though) causing it to pass fuel.

If the sled is running really cold then I'd say it's the thermostat, stuck open or missing. I think it should open around 130, just a guess though, check your manual.


Ken

[AL P]

50c? for what its worth, thats the temp of the thermostat in a differant sled i own other than my vmax 4. So i think you about hit it right on the head ken. I would imagine with all the cool air blowing through the hood via the hood vents, that the hose`s probley would`nt feel real super warm/hot. food serving temp is about 150/160F (which is too hot to eat, but thats what they say. LOL), so if you knock off 20 or 30 degree`s off that, and throw in some cold air, I`ll bet your heat is about right. and just to add a tad. as I`m sure you probley know, most cars average around a 160 to 195 thermostat so compared to how a car radiator hose feels, A vmax 4, should feel a good amount cooler. just my thoughts.

[Stanford]

That equals about 122F. I'll check my manual tonight and see what mine should open at. It has to either be stuck open or removed, like Ken said. There is no way it was anywhere close to 120-130F. I could hold the Radiator hoses with my hand and it felt "warm" to the touch, thats it.

[IZZ]

Stanford if your interested in the vent tube mod, Ive got pictures posted in a thread called "what to do....." I think its on the current page still. But Ken is right on the money - youve got to 1st tune the machine right, it has to be right before you consider doing anything else.
Owning a snowmobile means you have to learn how to remove your carbs and inspect and clean them every year without fail! If you havent done that yet - then thats probably why the jetting seems off. It explains the procedure of cleaning the carbs in the manual - very simple. The hardest part is getting them off, but after you do it a few times its very simple and easy even (cordless drill with long philips bit like 8" if you can find one makes it a snap) when you get the carbs on the bench and remove the float bowls youll see how easy it is to change the jets (use your manual to identify the differant jets and parts) IMO Id find out what the stock jets for your altitude should be and make sure thats what you have in there to start. That aftermarket stinger wont make a differance as far as jetting goes. Thats not the cause of restriction on these things - its goin 4 into 2 where you choke the exhaust flow, thats why its recommended to spend the cash on quad pipes. Read the pipe shootout article on the tech page for eye opening results of dyno testing. Anyway your carbs internals have to be spotless, thats how 2 strokes work, any foreign material in there and you can easily be rebuilding your motor, those jets orifices are tiny!
And as a testimate to the sticky enrichener jets (choke) that Ken mentioned, it happened to me, theres an actuator rod that runs the length of the carb rack to actuate the 4 enricheners and it can seize up or get sticky and not slide all the way causing the enricheners to stay partially on all the time or not open all the way. If its keeping those enricheners open even the tiniest amount youre gonna run way rich!

Also and this will catch alot of flack, but Im from the same school as you in regards to givin the motor more air! My airboxes are empty with the tops cut right off, Ive used 3m weatherstripping adhesive and airconditioner foam from Lowes to seal out hot air leakage between the top of boxes and hood, but Ive also sealed and did some cutting on top of the hood, under the instruments as well. Ill say this - its very difficult to jet for and I assume it will be finicky (not operate with the chosen jets at as broad an air temp or air density range as running stock boxes would allow) Its very risky and may or may not be worth all the trouble, youll definatly develop the knack to pull your carbs and change jets and reinstall them faster than most people can.

[AL P]

Just curious, what spark plugs are ya running? and what gas? ie premium, octane? maybe cheking the oil injector cable adjustment might be a good idea too? does it smoke alot? more than a normal two stroke would?

[Stanford]

Well I checked my manual and it says the Thermostat should open between 122-130F. I will inspect to see if the stock one is in there and if it is functioning properly.

IZZ, Thanks for the informative post. I will have to check all that stuff you mentioned too.

So far it seems I should do the following.

Pull Carbs to clean and inspect.
Check the Jet sizes and verify they are correct for my Temp/Altitude.
Verify Choke is working properly.
Check Thermostat
Get a new Silencer
Check plugs at Idle, Mid Range, and WOT to see what the mixture is like.

Anything else I am missing?

ALP - I only run 93 Octane and use BR9ES Plugs gapped at .30 per the manual. It doesn't smoke much except when I first start it.

I will look for the Oil Injector Cable in the manual. I will add that to my list.


Also I think some of you may be misunderstanding me. I should have been more specific. My plugs were black when I pulled them. These were from last year. I swapped them for the first start up this year, I always do. Old ones were tossed. I didn't mean to make it sound like it is running awful or anything. It doesn't smoke like crazy or run bad. It Idles flawlessly on it's own. The mid-range runs fine and it's very responsive. I can get up to 100mph in a flash when at WOT. I am just emtremely picky when it comes to my stuff. I like it to be perfect. The sled only has 2700 miles on it and it's 10 years old.

[AL P]

Sounds like you have a good plan. Your il injector cable is probley adjusted correctly then. i ust thought i would mention it incase it was ganging up, and flooding the plugs with oil. but like you say its does`nt smoke alot, so its probley fine. Good luck with everything, hope you find the problem. AL P

[Stanford]

Another quick question for you all. I have to rev to 5k RPM before the Sled moves. Does this indicate that work has been done to the drivetrain before I got it? It launches very hard because of this (I love it) however I was just wondering if it was stock or not. The only problem being traction, it spins the track harcore on any surface.

Edit- Well I just went out and checked my plugs, it was driving me crazy. I took a couple pics. They didn't turn out the greatest but here they are. The plugs look alright to me, light brownish color. The only thing that bothers me is the black coloring on the bottom of the threads. Is this normal for a 2 Stroke?

http://img.photobucket.com/albums/v311/psshhwhat/Mvc-019f.jpg

http://img.photobucket.com/albums/v311/psshhwhat/Mvc-013f.jpg

Also here is a picture of where the Pipes connect to the Silencer, does this look tampered with to anyone?

http://img.photobucket.com/albums/v311/psshhwhat/Mvc-027f.jpg

Here is another picture of the silencer itself, or lack there of.

http://img.photobucket.com/albums/v311/psshhwhat/Mvc-028f.jpg

Here is the part of the intake I was talking about modifying in the future. Just to clarify. Under the mesh is a rectangular opening that is much smaller than the opening up top. I was just thinking of grinding the opening to be a little larger. I don't want to lose power or mess up the powerband so I am hesistant to ever mess with it. It just looks awfully restrictive to me. However it may be tuned to the engine itself and not restrict anything.

http://img.photobucket.com/albums/v311/psshhwhat/Mvc-026f.jpg

I do apoliogize for all the annoying questions, some being repetitive. It's just that I would like to figure out exactly what is OEM and what is not on my sled. Also I just love to learn about engines and since this 2 stroke/Carb engine is new to me I am like a kid in a candy store.

Thanks and Regards,

[ALLSEASONRIDER]

5K is a little higher than mine, I'm at about 4K or so when I launch.

[Stanford]

Thanks for the input. I am going to assume mine has something modified in the Clutch/Drivetrain area then. I'll add that to the list of things to inspect.

[jeff242424]

MY 94 750 MOVES AT 3500 ON THE STAND AND ABOUT 4K ON THE GROUND, AS THE BELT WEARS WILL THE RPMS INCREASE FOR THE LAUNCH POINT???

RICK

[Ike]

Belt wearing will effect by rising the engagement rpm. 5000 seems a bit harsh. In that rpm you got more power than most of the 500cc sleds ever produce... LOL So no wonder it spins.

Check the belt too, if it still is in specs. Measurements should be in the manual.

Ike

[Stanford]

I'll add that to the list, it was replaced a couple years ago though. It squeels ever so slightly when I get off the throttle sometimes, so perhaps it needs tightened.

[AL P]

That picture of the spark plugs, looks good to me. tan/brown. its not real uncommon for the first three threads to have a black ring. atleast thats what i read at a spark plug dianostics site anyway. but the main thing, is the tip of the plug appears to ave about the right color in the picture from what i can see?

[Stanford]

Yeah they weren't black like the ones I pulled out from last year. I think they were just old from sitting all summer/fall and got corroded. I will continue checking these to make sure they look good like they do now and still do all the preventative maintenence on my list. Just to keep it running perfect and make sure it is running the full 150 stock Hp it should be.