cylinder washing

[glowpowered]

I have a 1988 YZ80 with std bore and a port and polish. the stock main jet is 280. would it be to much to run a 300 jet? i have heard of this thing called cylinder washing were the oil is washed off the cylinder wall by excess gas.

[extremetrailrider]

First off why are you changing the jet is it cutting out at top end? Or is your spark plug turning white with stock jet? If i was you and your plug is not turning white or it is cutting out at top end i wouldn't change the jet. There are actually 3 jets in your carb and you have to fine tune all of them and they are a bitch. Idk if 300 would work you just have to put the jet in there run it for a while then pull out the plug if its black that means your running to rich then you need to down size the jet. your main jet controls your throttle 3/4 to fully open

[glowpowered]

i know all this, but i got the bike in the winter and it came with a 270 jet which i think is to lean considering stock is 280. i went and looked for a 290 or 280 main jet but nobody has them in stock and i want to get this thing running now. i just did a complete overhaul on the motor. before the overhaul i was running a 300 but it was bored out .040 over. i have since sleeved it. thanks for all your help by the way