2008 150R cutting out before rev limiter

My son's 150 R is cutting out at high rpms in all gears. I would say at about 80% throttle. I thought maybe a dirty MAIN jet but the carb and tank have been pulled and cleaned. The jetting has been good although the last race was > 90 F. Now considering valves which we will check specs on tonight. Could this be valves floating from poor springs.? The bike has about 100 hours on it. He races desert minis. Any other routine race maintenence advice (piston, rings, head, etc) would be appreciated.

Check the index of the cam. The cam sprocket can slip altering the timing.

Just some quick thoughts,

if you count on this bike as the racer, it has 100 hrs. on it then a complete top end should have been done pre-season as preventative maintenance. Items to check are the TPS, cam as mention, float level, crack valve spring, and valve clearance.

The bike only had 2 hours on it at the start of this season. Everything was dialed in. The 100 hours was throughout the season as well as all practice sessions. Now is maintenance time as there is a break in the racing season. Thanks for the recommendations above. Upon inspection, the intake valves were both tight. Valve clearances on the exhaust side were in spec. Hot Cams shim kit is on order so this will be a starting point. Everything else checks out OK.

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