A very common 350x problem is that they get grooves in the head and head cap where the cam runs, I belive this is caused by a chunk of metal falling onto the cam and getting welded into the aluminum. That tube that is on the outside of the motor that goes from the bottom end to the top end brings oil right to the top of the cam and drops oil on it. So if there is a chunk of metal in there, your in trouble. Your running motor could have this problem, there's no way to tell until you take the head cap off.

I have 2 extra 350x motors, 1 of the heads is real bad with grooves, the other has one small groove but is usable, but 2 of the exghaust studs are broke off.

My question is this: does anyone know a way to fix the grooves in the head problem? I've heard of a cam that has bearings on it, my guess is that the bearing looks similar to a swing arm bearing. That would solve the problem but I don't know where to locate one, I've emailed web, no reply, looked on Powroll's web site and didn't find anything there, so I emailed them and am still waiting for a reply.