blakenator
New member
First off hello everyone, Im not a snowmobile guy never got into it but i drag race quads for fun so i thought id shove a snowmobile motor in a quad frame and am looking for a little help. I've search and search for my upcoming questions with not much result or maybe still looking in the wrong places. I have a 600 Yamaha twin... im trying to identify the model and specs on this bike. would love to purchase a owners manual but not sure which one i need being there are so many different types of these motors. I.E sx-xt-venture. i believe it maybe a 97 i have pics if it helps. Hope to get input good and bad
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s10mike
Member
ebay sells manuals on cds for yamaha snowmobiles. not as nice as a book, but all the info is on there. what are you wanting to know exactly? that quad will scream with that snowmobile engine on it. you gonna use the yami clutches? they are the best around. one thing about those yamaha twins, they kinda shake a bit. not the smoothest engine out there. but, they make good power. also, they like gas, alot! my brother had a quad set up for a snowmobile engine, but never got around to putting it together. post some pics on here when you get it done.
blakenator
New member
Well i cant figure out the year for parts, im mainly looking for a wiring diagram to eliminate most of the wiring harness, gas isnt a big deal ill finish this quad running on alky and the vibration should be ok its only 300 feet sand drags. One of my biggest questions is what clutch do i need for the motor the primary has a crack down the sheave and eats belts in about 3 mins. its a comet clutch but the silver sticker with the part number is wore off, i believe its a 108 but im not sure how i figure out the taper, the clutch is one of my last parts needed minus dual drag pipe. And im a huge 2 stroke guy so porting the intake and exhaust is like my first mod i usually do, you guys have and builders that have work with snowmobile porting, also i have 3 head gaskets riveted together from what i have read i can safely cut the rivets and make a thin gasket with this correct?... i wanna get all my mods done before i start dialing in the clutch.
First Id get a Yamaha primary and secondary clutch, are there any numbers on the block? I have a 97 600 twin as well and I have a manual for it I could check the S/N for you. If its a 97 most Yamaha clutches from 97-03 should work, the hardest part will be setting up the clutches depending on gearing. I would think the clutches will also spin up a lot faster compared to being in a snowmobile, since the quad is so much lighter and has a lot less traction, you may have to use stiffer springs and possibly add weight.
A layer out of the head gasket, twin pipes, reeds and fatter jetting and you should get good power out of that motor without making it too unreliable.
A layer out of the head gasket, twin pipes, reeds and fatter jetting and you should get good power out of that motor without making it too unreliable.
Some of the 97's had problems with snagging rings, most were fixed under a recall. If the motor has decent mileage on it and the cylinders look good you should be fine. Im at 10,500kms without a rebuild still pulls the sled to 103mph
The most recent Yamaha liquid cooled snowmobile twin engine design was in 1997-2001 model years, and in 500/600cc versions. These are similar to, but still different from, their predecessor: the 1994-1996 500/600cc version.
Yamaha sold a huge amount of these engines (sleds) from 1994 to about 1998 (most were 600cc) in the Vmax chassis and related models such as Venture, Mountain Max...
Can you post a better picture of the engine that shows the cylinder head better?
Can you post a clear pic of the side of the cylinder that shows 2 or 3 lines of numbers/letters. One of the lines should say 598cm3 for a 600, if not it should be something like 494cm3 for a 500. If the pic isn't clear enough, just post the lines here.
Also, somewhere on the cases should be a VIN-ish looking number, about 10 digits long or so. If you have a 1994-1996, there is a flat pad on the top case half with the number stamped in it, near the base of the RH cylinder and outboard from it (not front or back). If you have a 1997-up, I believe the number is somewhere on the flywheel housing where you can see it, again on the RH side of the engine.
Yamaha sold a huge amount of these engines (sleds) from 1994 to about 1998 (most were 600cc) in the Vmax chassis and related models such as Venture, Mountain Max...
Can you post a better picture of the engine that shows the cylinder head better?
Can you post a clear pic of the side of the cylinder that shows 2 or 3 lines of numbers/letters. One of the lines should say 598cm3 for a 600, if not it should be something like 494cm3 for a 500. If the pic isn't clear enough, just post the lines here.
Also, somewhere on the cases should be a VIN-ish looking number, about 10 digits long or so. If you have a 1994-1996, there is a flat pad on the top case half with the number stamped in it, near the base of the RH cylinder and outboard from it (not front or back). If you have a 1997-up, I believe the number is somewhere on the flywheel housing where you can see it, again on the RH side of the engine.
blakenator
New member
The motor is refresh it still has cross boring in the cylinders and everything its tight. pics in a sec
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blakenator
New member
heres some pics thanks for the help 
Great pics. 8CX-007841 indicates 1997 Vmax 600 XTC. The XTC doesn't matter for your use, it's just the model of sled the engine originally came in.
That engine and clutch looks like it has been out in the weather for a long, long time with that type of corrosion. When was the motor refreshed, and what exaclty was done, and do you know for sure that it was done? Those fasteners look like they haven't had a wrench on them in a long time, but hard to tell in the pics.
I don't know how much you have inspected everything yet, but I would at a minimum do the following:
- Pull the carbs, disassemble and check everything inside.
- Pull the reeds and check them as well as look inside the engine as best you can for sludge/rust especially on the crank and bearings.
- Pull the exhaust manifold and look at the piston skirts, domes, and cyl walls.
- Look for rust on the flywheel, stator, and pickup coil. Need to get the flywheel removed to do all of this, but you can look down thru that little hole in the top of housing while spinning the crank to look for rust on the flywheel. It may only be a spot that looks like the hole, but I suspect more.
- If you want to use the clutch with a new sheave, inspect the clutch as much as possible. Make sure the rollers and weights aren't all rusty, and make sure they pivot/spin freely and smoothly without a lot of slop. Same goes for the bushings, they shouldn't have too much slop sliding on the center shaft. It does look like a 108EXP clutch. You are likely better off just getting a complete different clutch, especially if anything is rusty/worn/seized on yours, or if you cant find a sheave affordably enough.
Good luck, looks like a fun project.
That engine and clutch looks like it has been out in the weather for a long, long time with that type of corrosion. When was the motor refreshed, and what exaclty was done, and do you know for sure that it was done? Those fasteners look like they haven't had a wrench on them in a long time, but hard to tell in the pics.
I don't know how much you have inspected everything yet, but I would at a minimum do the following:
- Pull the carbs, disassemble and check everything inside.
- Pull the reeds and check them as well as look inside the engine as best you can for sludge/rust especially on the crank and bearings.
- Pull the exhaust manifold and look at the piston skirts, domes, and cyl walls.
- Look for rust on the flywheel, stator, and pickup coil. Need to get the flywheel removed to do all of this, but you can look down thru that little hole in the top of housing while spinning the crank to look for rust on the flywheel. It may only be a spot that looks like the hole, but I suspect more.
- If you want to use the clutch with a new sheave, inspect the clutch as much as possible. Make sure the rollers and weights aren't all rusty, and make sure they pivot/spin freely and smoothly without a lot of slop. Same goes for the bushings, they shouldn't have too much slop sliding on the center shaft. It does look like a 108EXP clutch. You are likely better off just getting a complete different clutch, especially if anything is rusty/worn/seized on yours, or if you cant find a sheave affordably enough.
Good luck, looks like a fun project.
blakenator
New member
I had it all apart it was pretty weathered motor when i pick it up but it was all sealed up and i tore it down to check for rust that's how i noticed the cross boring in the cylinders, the clutch is a goner and i plan on buying a new one just didn't wanna pick up the wrong type being its like 350 for a new one. the secondary is clean, was stored inside the shop where i found this motor, carbs had the usual crap in the bowl but are all clean now, thanks for letting me know what motor i have it will be a lot easier to pick up a manuel for the wiring diagram.
Join here as a VIP and then you can contact a moderator to request the factory service manual. They'll send you a link to download an electronic version.
Unless you are very, very partial to Comet, consider picking up a Yamaha primary from that era or newer. They are plentiful and you can find good used ones for $150-$250 generally, and there are lots of tuning parts available.
blakenator
New member
what do i search for on ebay for a yamaha clutch?
BornYamaha
Member
Just put a post in the wanted section on this site. I'm sure you will have plenty of replies.
x2, I would search the classifieds here first, even post up a wanted ad.
Most of the Yamaha primary clutches from the early 90's up to today are the same general design, but there were changes/improvements over the years. As a starting point, maybe try to find a 1997 or newer clutch like what came with the engine. This would be a SHORT cover clutch normally found on the twins and lower powered tripples. You could also look for a 1998 and newer TALL cover clutch that came on the higher HP sleds such as SRX/Viper (The TALL cover was introduced on the 1998 SRX). Whichever you choose, note that the springs are different between the SHORT and the TALL versions, so for tuning you will want to buy the correct style springs, although you can use a thick spacer with a short spring in a tall cover.
You can also consider the clutches from earlier than your 1997, they are all SHORT covers, and depending on the sled/year they came from there are other minor differences to keep track of, such as the center bushings, roller pin diameters, etc. I can't list every configuration or change, as I haven't experienced all of them yet, but all of the normal repair and tuning parts are still available, you'll just have to keep track of what your clutch uses after you find one.
Reading thru the Forums here, the Tech sections here, as well as picking up a service manual will be a great help to you. Also, just as important for tuning is a Technical Update manual for 1997, or even a later year Tech Update if you pick up a TALL cover clutch.
If you want a really nice clutch, you could try this one:
http://www.totallyamaha.net/forums/threads/95398-Micro-Belmont-8-5-quot-Primary-clutch-for-Yamaha
Most of the Yamaha primary clutches from the early 90's up to today are the same general design, but there were changes/improvements over the years. As a starting point, maybe try to find a 1997 or newer clutch like what came with the engine. This would be a SHORT cover clutch normally found on the twins and lower powered tripples. You could also look for a 1998 and newer TALL cover clutch that came on the higher HP sleds such as SRX/Viper (The TALL cover was introduced on the 1998 SRX). Whichever you choose, note that the springs are different between the SHORT and the TALL versions, so for tuning you will want to buy the correct style springs, although you can use a thick spacer with a short spring in a tall cover.
You can also consider the clutches from earlier than your 1997, they are all SHORT covers, and depending on the sled/year they came from there are other minor differences to keep track of, such as the center bushings, roller pin diameters, etc. I can't list every configuration or change, as I haven't experienced all of them yet, but all of the normal repair and tuning parts are still available, you'll just have to keep track of what your clutch uses after you find one.
Reading thru the Forums here, the Tech sections here, as well as picking up a service manual will be a great help to you. Also, just as important for tuning is a Technical Update manual for 1997, or even a later year Tech Update if you pick up a TALL cover clutch.
If you want a really nice clutch, you could try this one:
http://www.totallyamaha.net/forums/threads/95398-Micro-Belmont-8-5-quot-Primary-clutch-for-Yamaha
s10mike
Member
x3 on that comet clutch. that baby would go in the trash if it were mine. I bought a sled with one of those junkers on it. it would eat belts, jam the seconday, and make the sled almost undriveable. I put a Yamaha clutch on it and boy what a difference. no more replacement belts, and it flies now. night and day .