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Exhaust Valve Leak After Top End Rebuild


CB750 Member
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Berkeley, CA
Thanks to all you wonderful people on this forum I've finally rebuilt my engine. I was super methodical to ensure I didn't make any more mistakes upon reassembly. Now that it's all together there are a couple issues I'd like your help addressing. First, the camshaft sprocket marks refused to line up perfectly with the head. I read AMC saying the exhaust side will usually sit up like one tooth and the intake side will consequently sit lower. So I did my best to get it as close as possible to level but this is the best I could do. Will this give me timing/firing problems?
I'm no photographer. I just did my best to show where the marks line up. The exhaust side is probably 2-3 teeth higher. If I brought that side lower the threaded hole on the camshaft itself wouldn't line up with the sprocket so this was the only position that worked.

The other thing I noticed is there seems to be a leak on the exhaust side of cylinder 2. I did 3 leak down tests and got readings of 25-35% leakage. All other cylinders ranged from 5-15% over the numerous tests. I realize the engine is supposed to be at operating temp so that might make a difference but does it make that much of a difference? Is it because I have yet to start the bike yet so nothing has seated properly yet? For background, I lapped all the valves and changed the seals. I replaced a few of the outer spring seats because they were lost at the machine shop. Before reassembly I measured everything multiple times and everything was within spec - springs, seats, valves, everything. Reassembly was fairly straight forward without incident. Before teardown, cylinders 2, 3, and 4 were solid in the leak down tests all less than 10% loss. Cylinder 1 had a massive 40% loss and now its the best performing cylinder at less than 10%. As always, any information is greatly appreciated. Thanks again!
'I read AMC saying the exhaust side will usually sit up like one tooth and the intake side will consequently sit lower.'

Like your first pic, you are retarded in first pic but too far. No more than a half tooth, NOT a full tooth if you can't hit on the marks.
I had the same issue. It was explained to me that the slack in the cam chains after 40 years tolerance stacks. It was recommended that I split the difference with an emphasis towards advance instead of retarded. Split the difference of the misalignment with the marks going more toward the back of the motor. Pretty sure this was slightly advanced. AMC can verify.
The marks slightly clockwise too much from left side of bike viewing is slightly retarded. Give it some thought, the engine has to turn more past TDC to get them to line up, that makes them late. Advanced would already be past the crank which is at TDC. Or counterclockwise too much. If you go that way you are advancing one tooth and it won't work.

You hit the marks using new parts or retard slightly using used ones.

When you advance cam you move in the direction of normal engine rotation, when you retard you go opposite engine rotation.