Will race gas hurt my stock YZ125?

Question

i have a stock 2006 YZ125 and I will be riding some very demanding trails this weekend. long hillclimbs like 2-3 miles long 2nd and 3rd gear wide open. im a fat @ss on this bike and I make it work harder than it should, but its all I could afford at the time. My point is, that after a ride like the one described, I am worried about engine heat and detonation. Can i run pure race gas or a 50/50 race gas, premium mix to lower temps and detonation? I use Torco full synthetic pre-mix oil usualy mixed 38:1 or 40:1 will I need to adjust my mixture with race gas? will i need to re-jet my bike? thanks for your help. oh i did go up 2 teeth on rear sprocket.

Answer 1

it shouldnt i run like 104 octane booster in my kx 125 and it is all stock

Answer 2

The stock engine is designed to run on 92 octane and it should run it's best on that. Your compression ratio determines the gas you need to run. With that said if you hear pinging or knocking when running pump gas then go with the 50-50 mix. It won't hurt it. You might try 32:1 for the application you are using your bike for. Also I would increase the main jet a size or two just to help protect the engine since it's wound out for long periods of hillclimbs. Check your spark plug color to see which direction you need to go on jetting. A nice tan color is what you want. I have melted pistons on two strokes more than once from riding race bikes in the sand dunes and would always rather be a little fat on the jetting when riding for fun.

Answer 3

not at all it will make it run cooler i do not recommend octain booster just race fuel mixed with your regular oil mix but i would stay more to thy 40:1 side who cares if it smoke a little more its safer for your motor. and no you do not need to re-jet

your carb.