I want to try some Koch 110 leaded race fuel in my son's 02 KTM 50 sx pro jr. I have been fighting a overheating problem and would like to give the race gas a try.
My question is will it run leaner or richer? and should I mix it with 92 pump gas?
the absoloute most common reason for the mini's with the auto clutch to overheat is a clutch issue. either the kid is a blipper or the clutch is engaging too early slipping causing heat to be generated in the clutch area. if you mosey on over to www.ktmtalk.com and hit the mini's section you will find more info than you can imagine on this problem.
another problem many people think is overheating is that the radiator looses water every moto. Well there is no surge tank so when the coolant expands it forces its way past the rad cap and out. If you fill the radiator only to the top of the fins inside the radiator you'll find it doesn't loose any after that.
Also there were some problems with the impellers if I remember correctly.
The ktm clutch wears quickly that is why I'd suggest starting there. Go washers, shoes, then drum as all three wear. A super hot setup is to take the Cobra shoes and grind the outside edges of the locating pins so they drop right in the ktm arbor and using the ktm washer stack you will find a clutch that hits hard and lasts long. As long as you keep up on your oil changes. I change after EVERY!!!! time we ride.