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Old March 24th, 2016, 08:45 AM   #10
jkv45
Rev Limiter
 
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Name: Jay
Location: WI
Join Date: Jul 2013

Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes

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MOTM - Jun '18, Oct '16
Quote:
Originally Posted by HoneyBadgerRy View Post
Its interesting that you can push these motors so much with such low octane. They must have great cooling and great valve cooling. I was scared that a 13.5:1 would need 110 or maybe 118 e85.
There are a lot of factors going on (chamber/piston design, timing, mixture, etc) but there are numerous hyper-performance cycles on the market that safely get by on Premium pump gas.

In general, to make max power, you want the lowest octane fuel that just barely keeps detonation away, and will lose power with any octane over that point. Detonation tends to start at lower RPMs and high loads, so you may be able to hear or feel it when cruising at a lower RPMs/speeds and opening the throttle significantly (heavy load).
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