Hey I've had teh F4i for 3-4 days now, already 250miles on her and the two times I added gas it was 91. The manual recommends anything higher than 86. Have you guys found diferent octane gas to work better?

 

use the search button next time

87 works good on mine even with a slipon exhaust

as long as you don't hear any pings 87 works for you

 

I'm convinced everything in this forum is now officially a repost.

Anyway. Use 87. Manual calls for 86, but 86 isn't very common. DON'T use 91+ octane unless you WANT lower performance, lower fuel efficienty and lower spark plug life. Use 87!

 

I use 89 and sometimes 93, both work just fine. On cool days its 93, on hot days 89. Reason is I try to keep the temprature under 220, but with street riding that does not even matter.
I have a system that is only complemented by my insanity, but it works. 93 on a cool day equals goot wheelie.

 

There is probably some variance from rider to rider and bike to bike, but I find that 92 works just a whisker better than the 87. I was absolutely shocked when I saw the 87 in the manual because these bike have really high compression ratios. However, I have tried the 87 and it seems okay.

Boo

 

Use 87. You'll notice a performance difference. At least I did. There's a link to a site where there's some tool that litterally broke it all down. Graphs, etc. Lower octane the better.

 

I'm gonna have to try 87, I have always put in 92

 

LoL yeah same here. I just assumed thats what it took. I need a damn owners manual [:@]

 

Read the owner's manual, there's some goodies in there!

 

compression is only partially responsible in regards to octane needed...don't forget timing, air/fuel ratio, etc.

for max power, you want all of the gas to combust and at the right time, when the air fuel is fully compressed. any earlier or later and you don't get optimal power. so basically, the mixture is combusting before it reaches max, then you want to up the octane...if it's after then maybe decrease it until you're right where you should be...(the second scenario is usually not the case). anyway, if you don't burn up all the fuels, which could happen with higher octane, then you're not make max power either.

believe it or not...lean makes more power than rich...but it's a general truth, not absolute.