Allright thanks I figured compression would have a factor in using the 2-ring design but I was not sure. Now I can add one more tick to my book of dirtbike knowledge

This is just an FYI, this has been a great thread to read, I just got off the phone with Eric. For a 133 (56mm bore) on the yz, you do not need to send in the bottom, it is only the 144 (58mm bore) that 58mm piston hits the front side of the cases and requires the bottom to be sent in. Whew, I feel relieved.


Dave

Eric, I'd like to ask you a couple questions myself if I could. First off what over sizes do you have to bore a '99 kx125 I know about the 144cc but what else?. Second is if I were to get you to bore my cylinder out to a 144cc what would I need to send you?. Third cost what does it cost shipping the works if you know?. And is there anything else you think I should know I was thinking of boring my bike out when the top-end goes.

Matt

You have the option to bore it to 133 or 144. The 133 is still ama legal in the 125 modified class. The 144 piston is availlabble from Eric and he's got killer prices, the 133 is availlable at the dealer and it's like the last oversize piston from the old Wiseco system (P8). 56mm instead of 54. There is no replacement for displacement...
For more info, you might want to check out his website. the link is on the side, Forward Motion. Or call him!

We just bougt a 144 cylinder and top from Eric.
It is for my wife's '02 YZ.
I can not wait to try it myself.
It is nice to read how good EG's work are compered to others.

Claus

So what ever happened to the KX167

would be long gone 9 year old thread