People keep harassing me about just changing one piston in a rebuild.I am only planning to bore one side and replace one piston. The other side is fine. Anyone done this? I don't see there being a problem. The added weight is going to be so minimal that it should have minimal effect on the balance of the engine. Wiseco pistons arent even the same exact weight anyways. They vary by a few grams which is about the weight difference anyways. Any input?
changing one piston
- Thread starter RideItLikeYouStoleIt
- Start date
WaveDemon
Not Dead - Notable Member
- Location
- Hell, Florida
if it has to be bored I'd do both. if it can be honed I'd just do one.
chrisdoc0608
insulting
- Location
- rocky mount, nc
- Location
- So. IL
I was just debating weather to do this or not. There are two things to look at. The weight and the power the new piston will produce. If the other cylinder is wore then the new one will produce more power causing an out of balance crank. The weight isn't a problem if you have a low RPM freestyle ski but is a couch where the throttle is pinned for extended periods of time then I could see the vibration causing a problem in the long term. Also if you have a standard crank that has some time on it or it is a welded crank. The vibration could cause a bit of slippage which would make things worse than before.
I went with boring all 3 cylinders on my project if that matters.
I went with boring all 3 cylinders on my project if that matters.
#ZERO
Beach Bum
- Location
- Florida - U.S.A.
Wiseco pistons in the kit have matching serial numbers and are within two grams tolerance.
Mouthfulloflake
ISJWTA member #2
- Location
- NW Arkansas
- Location
- So. IL
Hell no my 2 cylinder makes too much power for me I sure don't need another cylinder. It wasn't my motor just my project. I was trading a motor job for a new concrete patio for my moms house. But instead of doing it cheap I done in right.
Mouthfulloflake
ISJWTA member #2
- Location
- NW Arkansas
The other cylinder is still pretty good. It still has some hatch marks in it and piston looks really good. I dont think the new piston at .5mm bigger will make much difference in horsepower. I know the matching pistons are close but 90% you order arent matching so they for the most part arent that close. I know the CORRECT way to do it is to do both. I also know at work i tell people the correct way usually knowing that you dont always need to but my ass is on teh line if i tell them otherwise. I was just wondering if anyone had done this and ran into problems. I fell pretty confident that it will be no problem. I think the biggest problem would be to anyone i ever sell the motor to when they try to overbore it and its already bored. :Banane01:
Also anyone work at a machine shop that isnt backed up real bad? I tried a local place and they are backed up 3 weeks. Its like a 30 minute job and the summer in Mass is coming to an end quick.
Also anyone work at a machine shop that isnt backed up real bad? I tried a local place and they are backed up 3 weeks. Its like a 30 minute job and the summer in Mass is coming to an end quick.
- Location
- So. IL
I thought you worked some where so that you got parts at cost. They don't bore cylinders?
WAB
salty nuts
- Location
- coastal GA
I bought a spare cyl with used pistons off eBay a few years ago. I sold it to my friend when his top end went. He used it for almost 2 more seasons. Something unrelated caused it to go, but we measured the bore & it had mismatched bores. 1 was 81.5mm and 1 was 82mm. You could not tell, the power was great and did not vibrate more than normal.
I work at a dealership. They typically dont have machine shops in the back of a dealership.:02:
Thanks for info.
- Location
- So. IL
Really every dealership around here can do bore jobs. we have all of them locally honda, kawasaki, yamaha, seapoo, Oh.. wait do you mean Dealership like car?? My bad sorry
No, your right. I work for a yami, honda, suzuki, artic cat, ski-doo dealership. We sell dirt and onroad vehicles. We dont have an inhouse machine shop. We use one place and they are backed up for a couple weeks. I dont get a discount there so it isnt worth waiting.
How is "your" shop in business? :chairshot:
All you need is a hone or whatever it's called, no big complex machines.
Boris
The Good Old Days
- Location
- The surf-less coast
I have replaced one jug and piston on a triple before.(it's good to take spares when going away for the whole weekend).
Never had a problem spinning the motor over 7K RPM all day long for quite some time.
Never had a problem spinning the motor over 7K RPM all day long for quite some time.
Endo
Non-tree hugger
- Location
- Northeastern Indiana
Actually none of my local dealers have them either. They say they can do it but actually they go to a local machine shop. Honing yes...boring or anything beyond a helicoil and it gets sent out. Kind of pathetic actually.
While many shops & builders do have mutiple bore sizes in a given motor, I for one belive it to be nessary to have all bore the same size in a given motor. Espically if it's a performance built motor.
That being said, as long as all holes are a given size, it's perfectly acceptiable to change out pistons in said motor, as long as they are all of sound condition.
ski ya, Paul
That being said, as long as all holes are a given size, it's perfectly acceptiable to change out pistons in said motor, as long as they are all of sound condition.
ski ya, Paul
It would be an extremely poor financial decision for our dealership to invest in any machines for boring. 95% of the business is stupid things like oil changes and tire changing. I would say in the 2 1/2 years ive worked there we have needed to send something to the machine shop 10 times. A hone is totally different than a bore and would be done in house, but thats not really machine work. Not to mention we are not a performance shop. We are an authorized dealer. 98% of the public isnt trying to void a warranty on there new bikes by doing anything like big bore and the things that do blow up are covered and we send a jug back and get a brand new one. If you have a 12 year old RM250 odds are you are cheap anyways and going to do the work yourself.
- Location
- So. IL
That is really weird must be the location. There are 5 maybe 6 places within 30 minutes drive of my house. That can bore a cylinder if you don't count 2 local machine shops. Where are you located? I'm in southern ILL and the stealerships are doing major motor work everyday. They are as backed up as I am. I ride with most of the mechanics around here and they are swamped also.