Awhile back I redid the entire top end of a 200M I picked up. Motor was all really clean inside, sat for a long time, cam bushing was semi-seized onto the camshaft. I could turn it by hand, but very stiff and couldn't get the bushing off. Thought maybe from sitting for so long? Not sure. Anyways, I put in a new cam from a XR200R, new oem bushing, had the head all redone with new valve guides and valves all cleaned up, jug was cleaned up like new and bored, honed. New wiseco piston, 87 200X Carb w/ 118 main, and 40 slow jet, etc.
I pulled both clutches and cleaned out some grit from the clutch discs deteriorating. Cleaned out the cases on clutch side and mag side like new, and everything looked great. Oil pump looked like new, and the two o-rings are perfect. I thought maybe the motor had originally seized the original cam due to oil pressure, but doesn't look like anything was wrong.
Anyways, ran great after assembly, can't test oil pressure at head since both heads I have, the oil test bolt is snapped off. Was with a friend looking at some guy selling some atc motors and parts, and everyone of his heads had those bolts snapped off too. Common I guess? But took it for a ride, first day, for maybe 2 hours, ran great. At points I was definitely on the gas to get up some hills. Day two, maybe 15 minutes into a ride, took it down a road and had it wide open to see how it would go, and it really wanted to bog at full throttle, and would just die if kept wide open. After some cranking would fire back up, was guessing too rich, as my exaust seems to be pretty plugged up too, so that's not helping. Get going again, and a few minutes later it starts to die again, shuts down. Go to crank it, and the electric starter could barely crank the motor over. Figured the cam maybe starting to sieze? Or could the forged Wiseco be cold seizing on me? Figured it would have to be warmed up by then, though it was snowing out.
Kind of stuck and not sure what direction to go. Was thinking of using compressed air through the oil ports with the oil pump off? Not sure what could be in there blocking the oil flow. Also, can I use a different head with this jug? Not sure if the machining for the cam journals would be perfect, with an unmatched head and jug? Would like to be able to test my oil pressure at the head. At this point, no idea what caused it to start to sieze. After sitting for awhile, it cranked easy and fired right up.
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