baldjeff
CB750 Member
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'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!