Motorcycle Repair: 1973 Honda 350, cam lobes, compression stroke

Question
Bill,
I think I must be going nuts. I picked up a 1973 CB350 that would only run on one cylinder. I checked the compression and found good compression in the left but none in the right. I removed the engine and dismantled the top end. I found that it had been previously worked on and had new pistons, rings etc. the valves look good and clean. I put it back together with Clymers as my guide. It tells me to set the valve timing with the left cylinder at TDC and the timing mark at LT position. The L on the cam sprocket at 12 oclock. I did this and it can't be right. The left cylinder exhaust valve cam lobe appears to be 180 out from where it should be at TDC. I stuck it back together anyway thinking maybe they know something that I don't but I am no better off than before. I'm guessing the valve timing should be at the T mark on the rotor with right cylinder TDC. Am I screwed up or is the Clymers manual wrong. Thanks for your help...

Answer
Chris, the 350s are just the flip side of the 305s, with all the timing stuff opposite. You should set it up with the left cylinder up at the LT mark and the camshaft sprocket flat mark section parallel with the cylinder head surface (horizontal). What you are looking for is that the piston is at TDC and the cam lobes are DOWN, so the cylinder is on the top of compression stroke.

You can do the same thing with the right cylinder using the T mark and the cam lobes DOWN on compression stroke.

Which ever way you do it (shop manual copy I have here says LT), check the point cam orientation on the advancer. As you are turning the motor over (counter clockwise on 350s), the ramp on the point cam should be coming up to open the points at the LF mark alignment when the piston as at the TDC COMPRESSION stroke.

You can get the cam timing in okay in either orientation, but it can put the point cam 180 degrees out of phase. If that happens, just remove the point cam from the advancer and turn it 180 degrees and reinstall again.

Clymer's books are usually a rehash of the factory info, but both have been known to have errors.

Bill Silver