I got the bike back to the garage and started taking things apart. I ordered some tools, and to save on shipping, cam chain and slipper tensioner at the same time, since I know I want to change that. So here’s the first $200:

Here she is before I start pulling everything apart:

I drained what oil was left in the crankcase. Not much:

After 3 hours on Friday evening, I’d taken more apart than I ever had before, but still had a lot to go. You guys were right, and it was definitely the clutch pushrod seal. I think I’ll be fabricating one of those fancy seal retainers so this doesn’t happen again.

On Saturday morning, with the help of a friend, I finally got the engine out and on the bench. I took the advice of the fellow in the SL350 thread and removed the clutch and oil filter while the engine was still mounted to the frame. Some serious torque was necessary to get that oil filter out… I’d only tried once before, but didn’t have the proper tool and couldn’t budge it. There was only a small amount of sediment in there. Synthetic oil probably keeps most of it in solution.

The worst difficulty was removing the starter. We couldn’t seem to get enough clearance to remove the engine with the starter in place, and there wasn’t enough room to get a good whack on the impact driver to remove both starter screws. I was able to get one without too much drama, but one of them came out like this:

Signs of the oil starvation were immediately obvious. The right side of the top of the engine looked good (and was still wet), but the wear on the left side of the camshaft showed that it wasn’t getting oil. It was dry, and the lobes have visible scoring:

And then it was exactly as TheRadBaron predicted: The left side cam bushing was welded to the cam. Removing that took close to an hour. The technique mostly involved wailing on wooden blocks to pound it out…. Then adding a bunch of oil, pounding it back in, and then back out. After we’d getten it about 1/8th of an inch out, we switched to a technique that worked fairly well. One of us used a rivet gun (sophisticated air hammer) against a a large flat piece of metal wedged in the gap, and the other used a large, dull piece of metal to wedge from the bottom. That worked great, and because we were careful, didn’t mar either flange. We needn’t have been so careful, as there’s no way this can be used again:

The cam looked really bad, but it turns out that most of this metal was actually from the bearing surface, which is apparently softer than the cam shaft:

Here are both sides of the cam shaft:

It obviously can’t be used without being reground, but do we suppose this qualifies as a good core so that I can buy a new one?

Here’s the remains of the oil seal on the left side of the camshaft:

I’d say it got hot.

After we separated the camshaft from the left bushing, the engine spun freely. It turns out that was all that seized. The rest of the teardown went easily, and everything looked to be in reasonable shape (except the fairly well-worn tensioner wheels):

(don’t be bothered by the oil around the valve spring here, that’s runoff from the oil we were dumping on the camshaft to get it loose.

There appear to be some pistons stuck to the carbon:

I’m guessing this insane carbon buildup can explain my detonation problems. Still, I’m at 9,000ft, and I’d think that even with that carbon building up the resulting compression would still be low enough to avoid detonation. Though, the carbon probably also creates hot spots?

When I got the bike it was jetted for the altitude, but perhaps it was running very rich for a long time before?

I stopped shy of pulling the crankcase apart. I thought that the timing chain required a master link, but I see now that it’s actually endless. I was planning to just pull the new chain through with the old one, but now I’m not sure that’s as good a plan. I hate to break a perfectly good cam chain just because I don’t want to pull the cases apart.

But I really don’t want to pull the cases apart. It looks tricky with a zillion things that can go wrong. Everything I can see so far is in really good shape, so I really don’t want to mess with it. That said, pulling it apart seems like the smart option, so that’s probably what I’ll do. I ordered a tube of HondaBond, and I’m hoping that I can pull the case apart, replace the chain and put it all back together before I forget how it goes.