Compression on Stock GPR [Archive] - Bay Area Two Stroke

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reyefumi
08-02-2006, 12:46 PM
What's the compression ration on a stock GPR50? I know my race engine is getting a little tired since the NSRs are powering away from me down the straights. I just need to know what the ratio should be so I can how tired my engine is.

SecN8ure
08-02-2006, 01:56 PM
The service manual says 13:1 for the stock motor. Same for the SuperMotards.

shaggy55555
08-02-2006, 04:58 PM
are the GPR supposed to be as fast on the straights? just curious since the wheels are bigger which I think takes more HP/torque to move. unless it is compensated by gearing.

reyefumi
08-03-2006, 12:56 PM
are the GPR supposed to be as fast on the straights? just curious since the wheels are bigger which I think takes more HP/torque to move. unless it is compensated by gearing.

Yes, GPRs are supposed to be faster in the straights. That's why Matt set up the Formula 50 class to give the small wheeled bikes their own class in case they weren't competetive in the Super50 class. The GPR has more HP less weight. Unfortunately only TimO has been able to compete against the NSRs in the Super50 class. My bike is not running right and AlleyCat is still getting used to his GPR.