Quote:
Originally Posted by
Gravityfreak
OK so am I correct in understanding that:
1) We don't know of a high comp 'drop in' piston that is available for the XT660 motor?
2) A high comp Lets say (11.5:1) piston could yield anywhere from 1-2 hp though theoretically could be as high as 4.5hp?
3) No one has yet tried
just upping the compression on this motor and measuring the results?
Both my Yamaha wr250 and wr450 had 11:8 compression ratios and worked perfectly on 98 octane pump gas. Why wouldn't the XT660 at the same compression or 11.5:1?
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1/ We do not know of a HC piston of 100mm bore that will fit the XT.
2/ We do not know of a HC piston of a 100mm so the HP gain is theorey only if you are using a 10mm bore. We do know the HP gain with 102mm bore with a 11:1 piston.
3/ I have upped the compression from 10:1 to 11:1 using the Raptor 102mm piston & have full dyno results of Torque & HP gains.
I will make my next XT+++cc conversion 11,5:1. The Raptor boys run up to 14:1 with race fuel.