I PUT A POWROLL 273 KIT IN MY 250X AND I PUT IT BACK TOGETHER AND IT RUNS GREAT,BUT SOME OF THE BOLTS WILL NOT GET REAL TIGHT THEY JUST KIND OF SPIN, THEIR NOT STRIPPED BECAUSE THE THREADS ARE STILL HOLDING. BECAUSE OF THIS I HAVE A FEWW SPOTS WHERE OIL LEAKS (CAM CHAIN TENSIONER AND VALVE COVER). ANY SUGGESTIONS?

 

For the Oil leaks, new gaskets and silicone. But I don't have a problem with my bolts spinning, may have to get a shorter bolt so it stops turning.

 

I USED ALL THE SAME BOLTS, AND NEW GASKETS, THEY JUST DONT TIGHTEN UP

 

The 250X and 300ex are well known for the leaking valve covers. One you take it apart it will leak. I had mine cleaned up at a machine shop an used the orange high heat gasket paste to seal it up. No more leaks. As for your bolts spinning the alumium threads could be wonr. you may have to retap the valve plate or helicoil them