So with the season coming to an end, Im planning on overhauling the engine. My question is, what brand of pistons should I use? Should I go with OEM Yamaha? How are weisco? I've ran SPI before and havn't had much luck lol. What do you think?
Stay with the OEM Yamaha, they are the most durable.
sleeper_dave
New member
OEM is always a good bet. I don't think pro-x makes them for this application but they are quality as well. I have read some bad things about SPI. Wiseco are top quality and have been around forever. They are easily as good as OEM, however, forged pistons expand at a different rate with heat so you need to warm the sled up before you hammer on it. Also need to be careful about piston clearance, whatever you select.
Wiseco sells a complete top-end kit that can be had for about $250. Includes everything you need except new wristpin bearings.
Wiseco sells a complete top-end kit that can be had for about $250. Includes everything you need except new wristpin bearings.
Thanks, that weisco kit your speaking of must be the one Im interested in. Warming it up shouldn't be an issue cuz I do that anyway. I'd like to go oem but it's looking kind of expensive, unless anyone has a website to order from or something.
And ya, I rebuilt my old arctic cat with spi, and 150 kms later I did it again, with oem lol
smokingcrater
Member
wiseco's are VERY good pistons, if you let them warm up. They have developed a bad rap in the snowmobile world for that reason, people have cold seizures with them from not doing enough warmup time. You can't start it up, hop on, and let it rip. Even with a warmup, its best to take it easy for a couple minutes at least.
sleeper_dave
New member
I would also recommend running wider that recommended piston to wall clearance. They recommend .0025. I'm running more than that on my waverunner with cast (pro-x) pistons. My waverunner will run with no thermostat in water as cold as 40°, though. I had my cylinders honed out to .0032-.0038 (depending on where you measure) the other day.
I also found that what I thought was .0025-.003 based on feeler gauges was as low as .0018 in certain areas when measured with a micrometer and a bore gauge. Luckily I know someone with this equipment. If I had not had my cylinders honed (even with "stock" size cylinders and "stock" size pistons) I would have likely squeaked one.
My engine guy also recommended larger ring gaps, more in line with what the Yamaha manual recommends. Yamaha says .018-.024 for the 600, Wiseco says .004 per inch of bore which stacks up to .012. Then if you read more wiseco info on their website they say .0045 per inch of bore on the top, .005 on the bottom if you're running pipes. More if it's more highly modified. I'm going to start filing again and get them to the .018-.020 range and call it a day.
I also found that what I thought was .0025-.003 based on feeler gauges was as low as .0018 in certain areas when measured with a micrometer and a bore gauge. Luckily I know someone with this equipment. If I had not had my cylinders honed (even with "stock" size cylinders and "stock" size pistons) I would have likely squeaked one.
My engine guy also recommended larger ring gaps, more in line with what the Yamaha manual recommends. Yamaha says .018-.024 for the 600, Wiseco says .004 per inch of bore which stacks up to .012. Then if you read more wiseco info on their website they say .0045 per inch of bore on the top, .005 on the bottom if you're running pipes. More if it's more highly modified. I'm going to start filing again and get them to the .018-.020 range and call it a day.
flatblack97
Member
I used Wiseco prolites on my 97 when it was still a twin. Put on about 3,000 trouble free miles before I sold the motor.
SpartaSXr
Member
pistons
Google 40% off Yamaha parts. Stick with OEM and you will be better off in the long run, I had Wisecos and a buddy jumped on my sled and hit the field next door and smoked my motor for me. I will always use OEM from now on for that reason. First get the Yamaha part number from the home page and enter it into the other web site. Price comes right up and they are decent too. Good luck !
Google 40% off Yamaha parts. Stick with OEM and you will be better off in the long run, I had Wisecos and a buddy jumped on my sled and hit the field next door and smoked my motor for me. I will always use OEM from now on for that reason. First get the Yamaha part number from the home page and enter it into the other web site. Price comes right up and they are decent too. Good luck !
Thanks for that web page, I'll take a look around there for oem. Expect many more questions when this project gets underway! Lol thanks for all the help!
therealdangerdan
New member
Pistons Choice
Hey, so I JUST rebuilt my 94vmax 600 and started it lastnight, I got my pistons on ebay. they are Wiseco forged pistons I highly recommend them for the $265 I paid for the whole topend kit including gaskets, rings, pistons circlips, wrist pins, and even some cool stickers it was a very fair buy. I also replaced my crank with a rebuilt and that was a small fortune ($600) well worth it, remember if you redo the crank put in new seals at the same time. now the difference between yamaha oem pistons and wiseco forged is; oem ones are a cast which can shatter and forged pistons are much stronger. now this sled will scream just make sure you treat it nice with some good quality oil and gas and you should have no problems.
BTW this engine is very very easy to rebuild it was my first attempt at rebuilding any engine and it only took 3 weeks, because of the waiting time for the crank and seals. pistons were shipped in less than 2 weeks to my door.
Hey, so I JUST rebuilt my 94vmax 600 and started it lastnight, I got my pistons on ebay. they are Wiseco forged pistons I highly recommend them for the $265 I paid for the whole topend kit including gaskets, rings, pistons circlips, wrist pins, and even some cool stickers it was a very fair buy. I also replaced my crank with a rebuilt and that was a small fortune ($600) well worth it, remember if you redo the crank put in new seals at the same time. now the difference between yamaha oem pistons and wiseco forged is; oem ones are a cast which can shatter and forged pistons are much stronger. now this sled will scream just make sure you treat it nice with some good quality oil and gas and you should have no problems.
BTW this engine is very very easy to rebuild it was my first attempt at rebuilding any engine and it only took 3 weeks, because of the waiting time for the crank and seals. pistons were shipped in less than 2 weeks to my door.
smokingcrater
Member
therealdangerdan said:
and don't forget, plenty of warm up time! I know the typical advice with wiseco's is to wait until the heat exchanger is warm. I'm a little more impatient and don't like that much idling, I'll let it idle for 5 minutes or so, and then do some very low speed driving (10 mph or so) to get everything warmed up before hitting the gas.
Last edited:
What kind of oil do you recommend? Also, what octain are you running?
therealdangerdan
New member
So i would recommend either sythetic or Lucas Semi Synthetic, and I run 91 octane basic premium, I found when i put 94 octane it ran very hot and i believe that is what exploded my piston in the first place... no guarantees though.
s10mike
Member
go with oem yamaha.
