Shee' was running rich so I moved the needles down a clip, throttle was much more responsive everything seemed great. Hit the dunes today after about 15-20 minutes riding, it started to feel sluggish. I stopped looked down and noticed the cool head sticker was burning off the one side of the head, black goo and smoke came out from the head also. But only on the left side.
Got it home, tore the head off and the left piston is melted bad, the right hand one doesnt seem affected. I am planning on having the jugs bored and getting a port and polish done while im at it. What else needs to be done, this is my first ever ATV engine rebuild!
Below are pics of the melted piston and the non-melted, Im thinking that I had an airleak on the left side causing the destruction. If it was because of me moving the needle clip wouldnt both sides have damage??
left side:
Right side: