90 xr250r tdc

I'm having trouble getting my bike back together for some reason. It's a 1990 xr250r. To install the cam I turned the engine until the "t" on the rotor lined up with the mark on the cover, then aligned the marks on the cam sprocket with the top of the head, as the service manual specified. However, with the T lined up the engine didn't feel like it was at tdc, and now the piston contacts some of the valves. I'm rather stumped. The bike is a bit of a frankenstein, I believe the bottom end is from a '90 and the top on from an '86. Is there another way to find tdc besides the lining up the T?

nevermind, someone suggested sticking a rod down the spark plug hole and feeling for tdc, which worked. my timing mark is about 15 degrees off for some reason. She's running fine now.

2strokerfun said:

Timing mark is not for TDC. You probably have about 15 degrees advance on your ingition.

Glad you got it going.

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nah, the T mark is for tdc, there's a seperate mark labeled 'F' for ignition firing. Neither of them line up. I'm going to pull the flywheel off to check the key, but it looks to be fine so far. I'm thinking the previous owner just used some odd parts.