Piston?

[skyshot44]

I am building a YZ490 for ice racing.
Is it preferable to use OEM or aftermarket pistons such as Wiseco?

 

[fuzzy]

OEM's are generally only available for std bore so if you are doing a bore job then you will be stuck with aftermarket regardless....

But, back to your question....Wiseco's stuff is generally better than OEM, IMO. Nothing wrong with either one, but price is usually the main concern. OEM will probably cost you more making the choice obvious. I've used a couple OEM piston's on my bikes, but I got them used for less than $20 ea. I'll run OEM all day long at that price(until the bore is trashed)!!!

My 2c

 

[skyshot44]

I wasn't aware that OEM only had standard sizes. My cylinder is .5mm larger than standard, so I guess I will go with Wiseco.
Thanks for the tip!

 

[Rcannon]

The 490 has a liner that can be bored. Stop in at the local Yamaha shop for oversized pistons. They have them.