250-500cc Overheating

I have an 09 WR300 that wants to overheat when I am going up a long-gnarly hill. I came off of a KTM 250 and never had this problem. It does not do it any other time, anybody else had the same problem and might know what is thw cause.

Mine did that last season. Are you jetted too lean maybe?

The KTM 300's are well known for this as well. Many feel that the issue can be sorted out or improved with proper jetting. On the KTM 300 the greatest benefit seems to come from going up one size (richer) on the pilot.

My 300 boiled over one time not too long after I got it. I've since drained the OEM coolant and replaced it with some over the counter junk and it hasn't hinted at overheating again. And I've had it in some precarious situations that it probably should have overheated.

IMO the Agip coolant is junk.

Try Engine Ice with 3 capfuls of Water Wetter.

what jetting are you running? even with stock carb and fairly lean jetting (30p/clip 2/ 440 main) i couldn't get mine to overheat even on long 1st gear clutching climbs in deep soft sandy stuff. it was definitely starting to get warm then tho.