Hi i just rebuilt my 87 250R with a .060 over piston it has an old Paul Turner pipe and open airbox with a UNi foam filter and was wondering about the jeting. It was running a 160 main in the summer weaher with the old piston(0.040 over).But now its a fresh engine and the temps are aroun 0- minus 20 Celcius. My elevation is under 1500 feet . What size main do you think I should run and what needle position??

Thanks

 

Start off rich. Id say 168, and 3rd clip position, for those temps. Keep checking you plug dont forget.