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Discussion Starter · #1 ·
I've recently read some post about fuel octane. Many stating that 93 octane is the min. for this motor. I personally have run 89 octane since the the day I brought it home (with no prolbems..ping exct. even with big three +cam), mostly because thats the highest I can get in my home town (Southern Illinois @ sea level). I do have access to 93 but its a 20 min drive. Anyway my thought is this.... would'nt you be better off running the LOWEST octane your engine could safely burn since the HIGHER octane fuel is actually harder to ingnite?? It seems to me that the only way to extract more power from higher octane fuel is to either add compression (I guess a cam could raise compression psi) or alter timing. Feel free to straighten me out...... comments are welcome.
 

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If you can run a lower octane without ping and stuff... Then, it should be OK.

The higher the compression, the higher the octane needed. Higher octane fuels aren't harder to ignite, but they are more stable under higher compression... think of how diesel fuel fires. Lower octane fuels can pre-ignite (ping) under high compression... but higher octane can handle the high compression and not ignite FROM the compression like diesel fuel and lower octane fuels. But, when you add in the ethanol they mix with gas in the mid-west... ??

roadkill
 

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Living in California, I'm not sure what is done to the gasoline. I've used the lower octane with undesirable results. The 93 appears to work better in this machine. The manual says to use the higher rated fuel so I do it. I am at 2300 feet here and in the summer I noticed some pinging with the lower rated gasoline. Truly, with California changing from summer to winter blends (more or less oxygenators); it is hard to say how any vehicle can survive without reacting.:eek:hno:
Sid
 

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Discussion Starter · #4 ·
I built a small block chevy several years back with 11.25 to 1 compression and cast iron heads..... had to run it on 93
 

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93 is readily available around me so that's what I use. Manual says premium fuel only and gas loses octain as it sits. So if my bike sits a couple months without riding. I put fresh gas in it.
 

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on trails and roads u really wont see enough load or heat in the motor to detonate on 89 octane maybe even on 87, but put a really fat guy on the bike or put it in the sand where engine load greatly increases then u will have problems,... and the cost is A LOT MORE then just a FEW CENTS a gallon....Detonation will most likely run piston, cylinder head and cylinder...maybe even the rod...


on the contrary too high of octane will Hurt power(on low compression motors), the higher fuel octane will take longer to release the BTU energy thus suffering from higher rpm loss of performance...
 

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We can't eveether 89here in Aus, our options are 91, 93 and 98, I'm stoked that for once Australia has acess to stuff that the U.S doesn't
 

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I'm stoked that for once Australia has acess to stuff that the U.S doesn't
I would'nt go that far.....I have access to 87,89,91,93,100,110,114 within 3 local stations.....
 

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I run 95 and get it from the busiest (?) gas station near me . Always has fresh petrol. Something I read in "Dirtbike" awhile back. I can also get 100 octane from another nearby station but its not needed at the moment.
 

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I don't think you can get 93 anywhere in Nevada, 91 is it, so that is what I run in my 700XX. There are some stations around that carry 100, but I only run that straight in my 250R, or mix 50/50 with 91 in my other quads when I race or go to the dunes. Like DL700 said, 89 will probably be fine, unless you are riding somewhere that puts alot of load on the engine.

Doug
 

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87=Regular and 89="Premium" in my town both have 10% ethanol
I am in the same frickin corn belt dilemma here. U can still get 93 some places, but not many. I try to run 93 when I can, but 89 is the usual. E85 is taking the place of 93 at a lot of our stations now.
 

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I am in the same frickin corn belt dilemma here. U can still get 93 some places, but not many. I try to run 93 when I can, but 89 is the usual. E85 is taking the place of 93 at a lot of our stations now.
Is E85 , the stuff they produce outta corn or is a blend with petrol ?
 

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Its 85 percent ethanol in the e85 I think.
 

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Discussion Starter · #19 ·
I am in the same frickin corn belt dilemma here. U can still get 93 some places, but not many. I try to run 93 when I can, but 89 is the usual. E85 is taking the place of 93 at a lot of our stations now.
I think E 85 is 100 octane but I think you need special fuel system mods to run it..... Not to mention the 20% power loss and reduced fuel economy....Stupid Government!
 

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E85 is in the 105 octane range and you can run it your bike now, the only mod you must do is change your injector and retune to accommodate the approx 30% increase in fuel flow needed with E85.
 
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