HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
ThumperKid250F

48 hours should i do a piston or just rings and a wristpin.

11 posts in this topic

well long story short. my bike broke a wrist pin 2 years ago on the ice and i got it fixed by last years ice season.. since then i put 48 hours on my bike. 10 hours on the ice and the rest was in the woods.. so im just wondering should i just do a new piston and rings or should i just do a new wrist pin and rings?

btw im useing CP pistons

what does everybody change theres at?

Share this post


Link to post
Share on other sites

Help me remember what went on when your bike broke before. Were both circlips in the piston, or was one missing? Stock or aftermarket pins?

Share this post


Link to post
Share on other sites
Help me remember what went on when your bike broke before. Were both circlips in the piston, or was one missing? Stock or aftermarket pins?

both circlips were still in the piston and the wrist pin snaped in half. it was a weisco hi comp piston

only reason im asking is because i just dont want the same thing to happen again..

i no the piston is prob still good so new rings would make it like new and to be safe a new wrist pin..

can i put a new wrist pin in a old piston or does it come as a set?

Share this post


Link to post
Share on other sites

That changes the story a little, and I remember it now. You said you were using CP pistons, and I hadn't heard of one of their pins breaking before.

Wiseco did have a problem with marginal wrist pins at the time you broke yours, though. To be fair, I haven't heard of it for a while, so it may be they've addressed it.

Anyway. Wrist pins are made to a standard diameter for each engine since the pins have to fit the OEM connecting rods. The only possible difference that would affect fit is the pin's length, but that will matter only if the aftermarket piston has a significantly wider or narrower pin boss.

Yamaha sells the pins separately from their pistons, and a lot of people avoided trouble with Wiseco pistons by using an OEM pin in them. Most aftermarket pistons come with a new pin, but not all.

I would replace the pin with any piston, but at least in the case of a Yamaha pin, I wouldn't replace the pin where the piston was OK, unless it showed some damage. If you do a lot of ice racing, at least inspecting the piston would probably be a good idea at this point.

Share this post


Link to post
Share on other sites
That changes the story a little, and I remember it now. You said you were using CP pistons, and I hadn't heard of one of their pins breaking before.

Wiseco did have a problem with marginal wrist pins at the time you broke yours, though. To be fair, I haven't heard of it for a while, so it may be they've addressed it.

Anyway. Wrist pins are made to a standard diameter for each engine since the pins have to fit the OEM connecting rods. The only possible difference that would affect fit is the pin's length, but that will matter only if the aftermarket piston has a significantly wider or narrower pin boss.

Yamaha sells the pins separately from their pistons, and a lot of people avoided trouble with Wiseco pistons by using an OEM pin in them. Most aftermarket pistons come with a new pin, but not all.

I would replace the pin with any piston, but at least in the case of a Yamaha pin, I wouldn't replace the pin where the piston was OK, unless it showed some damage. If you do a lot of ice racing, at least inspecting the piston would probably be a good idea at this point.

thanks grey.. so would you say it would be ok to just re ring my CP piston and change out the wrist pin with another CP wrist pin ( just for a peace of mind) and it would be good to go, as long as the piston is in good shape?

Share this post


Link to post
Share on other sites

IF the piston is in good shape, yes, but that will be your call. Be certain to check the ring grooves for wear (excessive ring side clearance and "belling"), and the fit of the pin in the pin bore.

Share this post


Link to post
Share on other sites

You may already know this but order a new set of wire locks when you order the rings and wrist pin. Never reuse wire locks.

For what it's worth I would replace the piston.

Share this post


Link to post
Share on other sites
You may already know this but order a new set of wire locks when you order the rings and wrist pin. Never reuse wire locks.

For what it's worth I would replace the piston.

yes i no im prob going to replace the piston too. just asking a question thats all

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0