After getting the R52 home, I rode it around locally and began to get more comfortable with it. One problem is that I live on a steep road — nearly all of it is >16% grade and there is a short section that is 26%! This puts a big load on the 12hp engine, pulling both the bike and my corpulent self up the hill. It must have a running start and even though it is in 1st gear, it is necessary to stay on the throttle all the way. It's not possible to go up the hill from a standing start.

This led me to be concerned about how I was operating the bike. The English language owners manual gives scant advice about operating it. But it does say:

The italics are mine. The manual also gives some advice about richening the mixture on a hill (by closing the air lever) and retarding the spark to avoid knocking, but I found them maddeningly vague.

So, to get advice about operating the bike in the best fashion (and because I knew it would be a great time!), I made arrangements to go to the BMW VMCA Rally at Bench Mark Works in Sturgis, MS (read about the rally at the link). The trip was uneventful except that the bike broke down, just blocks from finishing a beautiful 50 mile jaunt along the beautiful Natchez Trace. And determining the cause of the breakdown overwhelmed the need to find out more about operating the bike.

The quick diagnosis of the problem was that the camshaft wasn't turning when the motor was turned over. While bad, it could have been much worse if this were an OHV motor, where a piston could have bent a valve. Below you can see photos from the disassembly.

The nut that secures the magneto gear to the magneto had come loose and dropped into the mesh between that gear and the cam gear. The abrupt stop this caused sheered off a tooth on the magneto gear and a couple teeth on the idler gear. Neither the cam nor the crank gears were harmed. This is because, while these gears are made from steel, the mag and idler gears are made from a material called Pertinax, which resembles epoxy-resin circuit board. Repops are available and not very expensive.

On reassembly, I also found that the tiny gear train inside the Bosch magdyno was also destroyed. I needed to buy 3 new gears and a bushing.

But as you can see below, I also found that the pistons were badly scored. Probably as a result of climbing the hill too much relative to getting good break in miles on flatter ground. Replacing the pistons and rings far outstripped the cost of the other repairs.

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