We went back to a 250, made more power and stopped seizing.
I personally went through around 14 pistons and 10 barrels. When we got the power we wanted we suffered with detonation and lack of revs. If we got the revs we didn't make the power.
We used both cut skirts and standard ones. We never had any trouble with exhaust bridges though. The wiseco's seemed to stand up better to the detonation but seized quicker if you didn't prepare the pistons.
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If I have to take the carbs off once more...