My '54 Velocette was problem free the 2 years I had it.
The '49 Triumph only had problems with the selenium rectifier, but that could be because I used the cheap ones from the radio/TV parts store.
The '39 ULH had no problems, but I was always working on it to try to get it as fast as the '49 Triumph.
In the 20 years I had it, my '76 XLCH only needed top end rebuilds every 90K miles or so, and the ignition advance wore out once.
So far, the only problems with my '03 America and '07 Nightrain have been batterys.
On the opposite end, I had a Honda scrambler for dirt riding and a small Suzuki twin for teaching people to ride. Neither of those engines could make it past 17K miles.
