harleyKmodel

When I check the timing I loosen the cable and advance it all the way (counterclockwise) and fix it with a wire so it won’t move. I hook up my tester I bought from Morris magneto and slowly turn the wheel forward until the tester beeps. Then I check for timing mark. Done it on 3 other XLCHs as well as countless Panhead, never with an issue.

I did the 180 degrees out on a 74 once. The nose cone engines use a small roll pin to prevent you putting the advance system in the wrong waya around.
But if your a bit brutal tightening the hold down bolt you can mash the pin and make it work.
Yes, the engine will run. But you will know well and truly something is wrong.

Check the flywheel pinion gear (24011-37). It may be loose and sliding back and forth.

Hadn’t found the smoking gun yet but the oil pump drive gear was on backwards preventing the oil pump from being time correctly. Not the first time I’ve seen that. I plan on inspecting everything very closely. Spent any time I did have today scraping the worst sealer I’ve ever seen. Still have gasket that won’t come off.

The pinion gear was very worn, both teeth and splines. It definitely could cause some variation but it doesn’t seem it would be as much as what I was experiencing. I reassembled it with a different pinion gear. Still need to time it, reinstall the carburetor and exhaust, etc. Keeping my fingers crossed that was it. Didn’t see anything else out of the ordinary.

Update- pulled the cam chest apart and went over everything. The first thing I noticed was the oil pump timing was off a little. The oil pump drive gear was flip flopped so that was an easy fix. Second the pinion gear was severely worn, mostly the splines but the teeth too. Lots of lash. Figured that has to be it. Put a new (used but tight) gear on and reassembled the bike with wind in my sails. Started right up but still seemed off. After running for a minute or so I rechecked timing. It was about 10 degrees off. I’m lost. Any ideas are appreciated.

Started right up but still seemed off.

As a "sanity check" I would now set the timing by using the piston position. I don't care what your timing marks say physics over rule any timing marks. 11/16ths BTDC.

There are simple tools for doing this, cheap.

Set the timing there, That is fully advanced 45 degrees BTDC.

Do that. Start the engine and run it for a minute.

Recheck the timing once again by using position of the piston, not timing marks. Continue to ignore them.

If the timing hasn't changed this time you can ignore the timing issue and start further trouble shooting.

If the timing HAS changed you will now have to look at your valve timing.

Anything funky with the mag mounting plate on the cam cover?

Hi Otis. Hope you are well.
From the text you have written, you are working on an engine you did not build. Problem solving takes a lot of patience, and you have reduced the error from 30 degrees to 10. Congrats. If you were thorough in your inspection and repair of the cam chest, there should be no need to think about that area anymore. You may have been dealing with a couple of issues. Aside from your original magneto, you installed 2 others in the engine and wrote that you had checked the drive gears for tightness. What about re checking the moving parts inside the head of the current magneto and re-do the point timing.
Patience will get you there. But that sentiment is easy to preach that from 10,000 miles away.

I plan on checking the magneto again for the sake of redundancy. I’m certain the cam chest is now correct. What do I use to check piston height without pulling the head? I tried that with a dial indicator but the spark plug angle is so steep I couldn’t get an accurate read.