Well look at you.  Nice.  Very nice indeed.

I needed to get a good look at the transmission gears.  Although the endoscope inspections had been good, I felt it would be much better to do a visual inspection through the opening in the case.  That way, I could be 100% positive that no pits were developing in the gear teeth.  With the cylinder removed, I had good visual access to the input gears.  The gears looked great.

The magnetic drain plug was better than ever.  Over the entire 20,000-mile test, it never picked up even a single chip.  I was confident that no main bearing fretting was taking place.

So, the high-speed pump and gear spray combined with the beefier 4-speed gear set seems to have solved the gear tooth pitting issue, and the oil holes in the cam lobes seem to have solved the main bearing fretting issue.  I think 20,000 miles is more than enough to confirm that those problems are behind us.

The cylinder head had a circumferential groove eroded into the quench area on the intake side.  It was perfectly aligned with the circumference of the cylinder bore.  Again, if any of you have prior experience with this condition please share.

Mike, I think the erosion on the piston and the slight groove on the head have the same cause since they are both in the same area.

I'd expect detonation to not be localized like that, but instead taking place all around the edge of the chamber.  But there might be some very slight differences in the piston/chamber that aren't readily visible that caused the detonation to be limited to those areas.  Maybe detonation starts there but is extinguished before it travels to the rest of the bore?

Michael Moore, thanks for your comment.  I also was surprised that the damage is confined to the intake side.  I assumed that would be the cooler area and less prone to detonation.  But I guess detonation must occur where the fuel is, and fuel certainly will be on the intake side.  The ignition source will be the rapid rise in pressure, and that pressure will be uniform throughout the combustion chamber.  I was able to find some YouTube vids of a Ducati that had almost exactly the same condition as mine.  I have no idea if the fellow that made the vid is an authority, but what he said made sense.

Zevengerie, I am confident that this is detonation rather than corrosion.  The ring land is deformed across the back side of the piston.  You make a good point about fuel droplets and fuel hiding out in the crevice above the top ring.  Smokey Yunik recommended reducing that crevice as much as possible without bringing the ring too close to the top of the piston.  He felt that the fuel trapped in the crevice could be good for something on the order of 5% more power.  Otherwise, it's simply wasted.  I may be aggravating the condition with my port configuration.  I increased the short side radius to improve flow on the bottom of the port.  That in turn results in more charge being directed at the area in question.  But I don't want to give up on the improved flow, so I'm gonna rely on the tried and proven recommendation to keep the quench as tight as possible, and reduce CR to a more appropriate level (as close to 10.5 as reasonably achievable).

I don't take any extra effort to blend in my seat angles.  I cut them and leave the corners as they are cut.  I do use four angles (75, 60, 46, & 30).  Thankyou for your comments.  They are very helpful and give me more to ponder.  

See my most recent post on this detonation issue.

I'm gonna copy and paste these replies into the new post that deals directly with the detonation issue.  That way, this post will be about oil system mods, and the other post will be about detonation problems.

Post where these comments are going:

https://suzukisavage.com/cgi-bin/YaBB.pl?num=1720767228

To forge ahead with the lube oil system testing, and to add a little more steam, I reassembled the top end with a new 97mm Wiseco Flat-Top.  I resurfaced the head, dished the piston to bring the volume up to a full 10cc, used a standard-length cylinder with quench set up at .038” (CR 10.6:1), and freshened up the valves.  It pumped a solid 210 psi and provided more than enough steam to torture the transmission and main bearing.  It’s the best motor combination I have assembled.  Very smooth and crisp with gobs of torque.  The piston is much closer to the stock piston weight and the vibration levels are very low.

The odometer was reading 66,522 and I had a fresh top end.  Who knows how many miles were on the bottom end.  It’s all eBay stuff.  But I had put at least 26,000 miles on the gearset and 20K on the Left-Hand Main Bearing.

I resolved the bearing failure problem using the shotgun approach; get as much oil to that bearing as possible.  I had been running a Hayden KrankVent.  That KrankVent is a check valve installed in the breather line.  It results in a slight vacuum in the crankcase when the engine is running.  That slight vacuum seemed to mitigate many of the little aggravating weeps around places like the oil fill cap, the clutch cover, the timing plug, the alternator cover, the clutch release arm, etc.  That was a nice feature, but I couldn’t be sure that it was not preventing proper drainage from the cylinder head.  I knew that those head drains supply oil to the main bearings, so I removed the KrankVent.   Now that all seemed well with the bearings; it was time to try the KrankVent again.