Race Gas in a CRF 450

[Shig]

Yesterday, a buddy and I met at a local track in rainy conditions. He has an 02 CRF 450 with a 172 main jet, and my 04 has a 175 main. Both bikes ran fine when we first arrived. We both were low on gas, so we each purchased 1 galon of 100-octane race gas which we added to about a quart of pump gas already our tanks. I noticed a significant performance increase in my bike, particularly on the bottom end. His 02 was barely rideable. It idled fine, but when he cranked the throttle to 1/2 throttle the RPMs surged and fell like it was bouncing off the rev limiter. Any idea what could cause this?

 

[DEANSFASTWAY]

Maybe he got a little water in the gas when he adeed fuel . When they have a little water in the bowl the idle circuit sometimes wont pick the water up but gets sucked throughthe main jet easier. Main jet id usually a bit lower and the water settles to the bottom of the float bowl. Id Try to drain the bowl first and if that doesnt fix it then Id try straight pump gas . Good luck

 

[bedell99]

I'm thinking that the gas you bought might have been oxygenated and put your friend who has a leaner main in a lean condition. What type of gas was it??

Erik

 

[Shig]

You both might be right. Since it was raining, its possible that some water got in. Also, all of the gas in Metro Denver is 10% eth. Mystery solved, thanks guys!