CB77 cam install issue

[prodigal son]

I made the novice mistake of using the LT mark instead of the L mark on the crankshaft rotor to time the "dot" on the camshaft sprocket. Finding I couldn't set the valve clearance, I disassembled and used the L mark this time, and that corrected the problem. Having done this It didn't feel like I had any valve/piston hitting issues as the motor moved easily. Could I have bent a valve with using the LT mark? Thanks, Gary

[Michael Stoic]

Could I have bent a valve with using the LT mark? Thanks, Gary

Gary, That depends on how much and how hard you tried to spin the motor against the bind - if any - before the reset.

If it spins freely now, do a compression test. That could surface an issue or confirm cause for optimism.

[prodigal son]

When noticing the issue, I was turning the crank with a 14mm with just a couple of fingers. With it corrected, it didn't turn any different. Since the head is off you think I could close both valves and pour some mineral spirits in the chamber to see if a valve is off it's seat? thanks for the response, Gary

[Michael Stoic]

Testing for a leak that way - maybe. If the gap is very small, unpressurized oil might resist seepage because of its own viscosity.

Light source from behind the valve - like from an LED bulb - might be useful here. A 5mm bright white LED (12V + 680K resistor) is a tiny assembly that you could position exactly where you want it - as close on the stem side of the valve as possible. Photons will seep through any sized gap.

[prodigal son]

thanks Mike, I'll try the dark room and brightest light I have. My mechanics mini video camera has a bright light and will get into the ports. Thanks, Gary

[Tim Allman]

If there is a mistake to be made in assembling a CB77 I have made it. :-(

My bike survived this without a problem so I expect that yours did too, especially given that you were able to turn it over easily. If you can see inside then look for appropriate marks on the pistons. The valves are very hard and stiff and should leave evidence of a contact.

And, I agree with Michael; a compression test should reveal any problem.

I hate it when I do things like this.

[prodigal son]

Tim, Thanks for the response. Not wanting to have another sleepless night I decided to remove the valves for inspection. Getting a late start, I put the the right exhaust in my lathe and saw no run out. Next I used layout blue on the valve seat and hand turned it in the head exposing an even seat mark on the valve. I think I'll do them all just to double check everything. I'm waiting for another head gasket as I'm not confident about using a torqued on head gasket over. It's 5 below zero here so no hurry. Gary