H2RTuner wrote:
There is NEVER a reason to run loose piston clearances, nor "looser" center cylinder.
Even when we ran the 171 horsepower H2-R engines, with forged pistons in Yvon's bikes, piston clearances of no larger than .0015 worked better than all those worn out bores freshly clearances to .003+ loose. We never seized the engines, and thet always ran incredibly well.
One main loss with loose piston clearances is too much piston rockover at TDC and BDC, and the piston splayed down and up the bore, destroying effective ring seal.
The rings are nit barrel faced, they are square. The more rock over and splaying, the less ring seal, the shorter the piston life, the worse the engine runs, no matter if it is a single ring H2-R, ir two ring street H2.
And, YES, the second ring expanded on street pistons is nescessary, should never be left out, it helps to reduce piston splaying, and helps with ring seal..
Good info!
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