Bragging, then asking for a noise diagnosis

I'll get the happy bragging out of the way. I redid the top end on my KZ750L3 and rode it from Seattle to Tijuana (through the Nevada desert) and back up 1 and 101 to Vancouver. It was great. Now I'm back.

The problems that cropped up:

100 miles from departure, my starter crapped out, so I push started it the remaining 3300 miles. I'm gonna take that apart and look at it.

I developed a minor base gasket leak. My cam chain tensioner was also leaking pretty badly and I got the leaks confused. It was bad enough that I had to wash it off because I was getting oil on my tire. I'm using Rotella T 15w-40. I'm going to remove the tensioner and put gasket sealant around it.

I developed a crack in my muffler on the last day. It's about an inch long and I can see through it. Is welding my only option there?

Last, and most concerning, is a strange grumbling noise that happens at low RPM. I was leaking air through my carb mounts, so I sealed them with 1194. Since approximately then this has been happening. It's most severe starting in first gear from a dead stop. I would describe the sound as like hard rubber beads tumbling around in a bag. When the RPM climbs high enough, it seems to go away, though it may only be road noise covering it up.

Any ideas about the sound?

not sure about the sound, but if you ship your bike to

KZ1K
pothead lane
cloudnine,fl 8675309

i can assure you you will not spend as much having to fix all the issuses.

Exhaust leak?

I'm gonna have the exhaust crack welded. I have no idea what the low-rev grumble is, but I'll take it to someone who knows sounds.

Someone warned me that igniters on these bikes go out frequently and once they do, you're close to SOL. Could running on 3.5 cylinders be a symptom of a dying ignition coil?