Jetting For Race Fuel

[roofd]

Right now I am running about 1/2 91 octane gas and 1/2 110 octane gas. It is still a little lean, especially in the winter, and needs to be jet ted more. I have decided to just jet it for straight race full since I still need to jet it anyway. When going from a lower octane rating to a higher one how does this effect the mixture, leaner or richer?

 

[courchaine]

It's not suppose to affect the mixture ...the things that lean your mixture is the weather....octane as basically nothing to do with that.....it's the same as normal gas 14:1 is still the best mixture...

 

[troys3175]

What compression are you running that requires 1/2 110?

 

[dswwarrior350]

With race gas its hard to jet using the plug as its going to be grey all the time due to the lead. Basically you have to go from just how it runs.. however when switching fuels ive never had to jet yet.

 

[roofd]

I'm running at almost 12:1. The compression test was around 11.75:1.

 

[boondock]

I was told today by a yamaha race mechanic that me running a 10.25.1 high compression wiseco piston bored to 84 mm that i have to run the race fuel or the spark knock will shatter the piston etc anyone else heard this ..???

 

[courchaine]

No....you don't need tu run race fuel with only 10,25:1 ......I only suggest getting race gas from about 11.75: 1.....but if you have the money go for hit....a coolder engine is never bad

 

[troys3175]

I was told today by a yamaha race mechanic that me running a 10.25.1 high compression wiseco piston bored to 84 mm that i have to run the race fuel or the spark knock will shatter the piston etc anyone else heard this ..???

Don't let that "mechanic" work on your stuff, he obviously doesn't know what he's talking about. A stock yfz is 11.4:1 compression and yamaha recommends premium pump gas so why would your 10.25:1 require race gas. You don't need race gas until you are around 12:1, even at that you really only need to mix 3or4:1 pump to race.