[Eric K]

The GasGas 2 stroke should not overheat with the stock rad cap if it is 1) jetted correctly, 2) you have enough airflow and 3) the cooling system is in good working order. My riding buddy, son and I run our GasGas 300's at high elevation (up to 6000ft), warm temps (80F), climbing long hills (miles of climbing w/tight switchbacks in 1st and 2nd gear). I often give my 6 year old son a ride. Our combined riding weight is about 370 lb. The only times I had overheating were a) when the waterpump seal failed and the coolant went into the case and b) when I had radiator guards. Otherwise, it does not overheat. I have a temperature tab on the outside of the cylinder near the head. After a long hard climb on a warm day with my son along the temps are around 200 deg F.

I would check the plug right after you get to the top of the hill to get an indication of how lean you are during the overheating condition.

Some radiator guards significantly restrict airflow. If you have radiator guards, I suggest you remove the guards and put the stock louvers back on and see if there is a difference on the overheating.