Rear Wheel Lockup at the Track

[svgarage]

Good theories. Glad I have the HPI unit, which may mitigate the problem.

Another interesting find on my part. I got the 64.50mm Pro-X pistons in the mail. I measured them against the ART CruzinImage 64.50 pistons. The Pro-X measures at 64.36, while the CruzinImage measures at 64.44. NOS Yamaha pistons measure exactly the same as Pro-X. The holes were originally bored for the Yamaha slugs. When I replaced the NOS pistons and installed the CruzinImage pistons, we just did a quick cleanup and in the went- and they ran great till I really pushed them. Now that I'm back to the smaller pistons, wondering if that alone will alleviate future overheating issues?

[m in sc]

that would def explain it by expounding the issue. yeah, don't ever mix brands between bores. aside from dimensional, there's also material composition differences that may affect clearances when hot. art/pro-x are interchangeable though.

[Striker1423]

Mine killed the left side too. BRP remedied the left-side seizing issues on their snowmobiles (Something to do with dwell time after the rotary valve rotated around) by upping the main jet on the primary (clutch) side two sizes over the right. I remember my 670 Ski-Doo had a 320 main on the left and a 300 on the right. The right-side of course having the transfer case (oil bath).

Honestly wouldn't hurt to do something like this to a track bike if this issue repeats itself.