I recently had the carb bored to 39.25 mm, and the head shaved. (for the second time)
I was told that I will need to mix in some race gas. (50/50)
How do I know for sure that I do?

My bike will start up and run fine, when the motor is cold. (still has regular 91 oc gas)
After I shut it down, and try to restart the warm motor, it is more difficult.
Sometimes it will backfire through the carb, (or the pipe), and sometimes it will just about break my leg from a kickback.

When the motor is running, it seems to run OK up and down the street on regular gas. (but how do I know for sure?)

 

I would try it and see what it done. Sounds like you have the mods that would benifit with some higher octane. Then I would try mixing some with the 92 pump gas.

 

Hey 350X what's up?I sure know what you mean about the back kick,ok do you have the stock stator or aftermarket?Mine did that and I had the timing too advanced.Also it could be sucking air around the carb boot.you have the Kehin carb right?, does it have and air fuel mixture screw?you may have to adjust that.I know a fouled plug will do that too.As far as how to tell is the engine will predetinate cause excess heat do to higher compression,what higher octane gas does is burn more slower so heat build-up and predetination do not accure.I hope I helped you out....Zilla

 

Hey there ZillaDaddy, my bike has the stock carb, bored out.
Stock stator too. Ill try and put some race gas in there and see if it improves the starting.


-Matt