The BIL picked up some VP110 gas to try in our bikes and we took them (my '72 Honda CL175 and his '81 CM400) for a spin yesterday. My little 175 is pretty sensitive to pretty much all variables, being so small it's very obvious when something is hurting power output. It's all stock, 9:1 compression, 2-valve SOHC, dual slide-valve carburetors. I was just above reserve level with Shell Vpower + nitro 93 (no more than 2 qts.) before I put in a gallon of the 110 fuel - by my math that comes out to approx. 104 octane and, if the Vpower is E10, about 3% ethanol.
Power was slightly better but not night and day, however the bike now willingly revs up to 10,000 RPM or better (redline is 10.5) when before it would peter out at about 8,500. What gives? There seems to be no consensus on what octane is or isn't - octane only affects knock resistance and does nothing to increase power (in contradiction to what I've witnessed personally), lower octane fuels burn hotter and faster generating more power in low-performance engines that won't knock anyway... yada yada yada. But the facts is the facts, my little bike will rev higher on leaded fuel with 10 points higher octane than the unleaded, ethanol-blended 93 I've been putting in it all along.
Power was slightly better but not night and day, however the bike now willingly revs up to 10,000 RPM or better (redline is 10.5) when before it would peter out at about 8,500. What gives? There seems to be no consensus on what octane is or isn't - octane only affects knock resistance and does nothing to increase power (in contradiction to what I've witnessed personally), lower octane fuels burn hotter and faster generating more power in low-performance engines that won't knock anyway... yada yada yada. But the facts is the facts, my little bike will rev higher on leaded fuel with 10 points higher octane than the unleaded, ethanol-blended 93 I've been putting in it all along.
