After completing the ignition rotor and cylinder head nut bulletins, and checking my valves, I put my bike back together. When I fire it up, it idles for a few seconds, then backfires and stalls. I seem to have screwed up the timing. I was very careful to do the bulletins one bolt/nut at a time. I carefully checked the cams to make sure I reinstalled them properly according to the timing marks on the camshaft gears. Any thoughts on where to look next?
Yes. Did one cylinder at a time. Did the ignition rotor before removing any valve covers. Went back and checked TDC for each cylinder by putting a metal rod down the plug hole.
Well, I did notice that part of the rubber fitting between airbox and rear intake manifold had gotten pushed under the airbox when I reassembled the bike, but my local wrenching friend didn't think that would cause this problem. Could he be wrong? When I first tried to start the bike, it wouldn't idle at all. I left it alone overnight, then tried the next morning. That's when it started backfiring and appearing to exhaust back up the carbs.
Looks like he was. Put the airbox and carbs back on and the bike runs like a champ. Moral of the story: be really careful when putting hoses and grommets back together. A little silicone grease goes a long way. From my experience so far, reassembling the airbox/carbs is the hardest part of working on this bike.