Originally posted by LTurboR450+--><div class='quotetop'>QUOTE(LTurboR450)</div>
IMO higher octane fuels will NOT richen the A/F mixture, however it will help with engine detonation. Just because the engine is a 11.7:1 compression doesn't necessarily mean you don't need high octane. Altitude and ignition timing also play a part.
your opinion is really quite correct, and thats not just my opinion. it is a fact that higher octane fuels or any kind of race fuel will NOT help with lean conditions, nor will it change the A/F ratio at all. higher octane fuels and race fuels are designed for 1 purpose and 1 purpose only, to be harder to burn so as to prevent detonation at higher combustion chamber pressures. if you are not detonating, there is no need for high octane race fuels. i am currently running just your run of the mill 93 octane (usually exon or sunoco, they are cheapest around here by 5 cents or more) straight out of the pump, and it has been 60-70 degrees the last 2 weeks and colder durring night riding (something i do often) and i have had NO problems at all. my R450 has a CB, full Yosh RS-5 exhaust with sparky removed, and air lid removed.
some more facts about fuel. the octane rating in fuel has NOTHING to do with oxygen. higher octane fuel and race fuel will NOT produce more power by itself, it is actually HARDER to burn than lower octane fuels and will actually make you LOSE power if you dont have enough compression+ignition to burn it (not a problem with the r450) it simply allows for higher compression/more boost without detonation, which in turn make more power themselves. oxygenated race fuel is very BAD for your r450 unless you have the capabilities to tune your fuel system for it, if not you will run VERY lean and probably damage your engine eventually (or instantly). leaded fuels really can cause more harm than good on todays engines and not just because of the o2 and cat, you really can damage the valvetrain with leaded fuels, todays engines are not designed to cope with the lead. titanium valved engines especially have problems (so i have heared from many respectable sources anyway, i dont know for sure if titanium valves make any difference, good or bad)
and while we are on the subject of fuels, octane boosters...... know that the "octane points" (your octane booster will say "increases octane by this many points") are not the same as the "octane number" (which is the actually octane number like the ones on the pump, 86,89,91,93,ect...) the octane points actually add up to more than the octane number. as an example we will say your standard lucas octane booster raises your octane by 10 points, than it only raises your octane number by 1-2 (from say 91 to 92-93) i dont know the exact ratio of points to numbers, but just to get the point across that dumping octane booster that raises your octane by 10 points into your tank is not gonna raise your octane from 91 to 101, its not even gonna be close[/b]