A little puzzled...

[danjerman]

I have been trying to find out what make my piston was for some time, and now that I know, it's brought on a whole other slew of questions. Just today I found out what make my piston was for those of you following the thread in the Maintinence forum, it's a Wiseco. I was told you can tell by the "W" stamp in the underside of the piston. Anyways, after I found this out, I called wiseco to order some new rings and circlips to complete the top end. They had a little trouble finding the correct size rings for that piston, because according to them they didn't make a 73.95 MM piston for a 91' KX250. Finally after being redirected to LA Sleeve, I asked them if they made an overbore for a 91' KX250, no such luck. But they did find the piston I have, turns out its for a KXT250, a q-u-a-d made in the mid to late 80's! Now I haven't had this bike for too long, so this is very suprising to me to find out that I had a 300cc Monster this whole time, especially since the piston is for a KXT250! How could someone figure out this piston could work in this cylinder, especialy this big of a piston? Also, since no other mfg to my knowledge makes pistons this big for my dirt bike, is it safe to have this big piston in there? I haven't had any problems so far after about 45 hours of slow riding on the top end, should I expect any?

Thanks

 

[Rcannon]

This sounds crazy, but I have the same piston in my garage. Mine was supplied with a big bore kit I bought off of Ebay. My bike is a 1997 YZ 250.

 

Eric Gorr said it was a piston available from Max Power. It appears the same piston is used in the YZ 250/300 kit as well.

I imagine someone used this company for your kit. Does your cylinder have a liner or is it a nikasil bore.?

 

[danjerman]

It has a steel liner in it. But I'm more coaught off guard of how someone could pull a big bore like this off, with a q-u-a-d piston! LA Sleeve said they didn't offer a big bore kit for a 91' KX250, but I'll have to look into that max power thing.

 

[Rcannon]

I am not sure it really is a quad piston.

I talked to a local machine shop. The owner said if a company designs a piston and has weisco make it, that specific company has the rights to sell it.

This would also allow the company to really slap it to you if you need a replacement.

 

[jmics19067]

RCannon, actually there is a lot more to the lock up of parts than that.

Believe it or not due to corporate contracts and stuff you can specify that noone can sell something that you are paying the exclusive rights for. For instance if you went to General Motors to buy an engine no problem plunk down your money, but if they happen to ask you what it was for and you say for a Hyster forklift,GM cannot sell it to you.Since Hyster owns all exclusive rights for anything that is related to Hyster. Same short block just that how the contract is stated you have to wait till GM sells the engine to Hyster so THEY can sell it to you . It doesn't really have to be a specific design just a specific contract.

It could easily be an existing design piston that whomever locked up thru contracts for their specific application. You can go to Wiseco and say I need a piston of such and such design for a specific application and they will tell you you have to buy it from the company that locked it up,but if you go there telling them I need a piston of such and such shape to use as a paperwieght they can sell it to you.

Of course you also have the possibility that presumably Power Max<the believed company at this time right?> bought a bunch of existing pistons that where close in design and than modified them slightly to work for their specific design. Rendering a stock design piston useless recquiring an availability lock to prevent future liability issues.