Looking at '83 R80RT with electrical problem

[Darryl.Richman]

This is not my forte, but I think that unless the bike has really low miles and is a great looker, the seller is asking too much. The R100 of that era is more desirable, especially in an RT model.

Also, the '81-'84 years have a problem that an owner will have to correct at some point, and it would be good to know if the seller has had the work done. BMW changed the metallurgy of the seats and valves in anticipation of the removal of lead from gasoline in this period. Unfortunately, their choice wasn't so good, and the seats don't transfer heat from the valve heads well. This causes the valves to "tulip" eventually and lose the adjustment setting very quickly. Besides the valves, the correct fix is to replace the seats as well.

(On the positive side, this is when BMW went to electronic ignition and Nikasil cylinders, both great improvements over the previous bikes.)

Regarding the charging system, it sounds like there's an intermittent, and possibly heat related, problem. The charging system has two weak spots, the so-called "diode board" (voltage regulator) and the alternator rotor. It may be that the rotor is on its way out. They are available, try Motorrad Electric. They also have a book on the electrical system that gets great reviews.

Good luck!

[VBMWMO]

There is a local '83 R80RT for sale. It seems to run well and looks pretty good. It has a charging problem that the owner has not resolved. Periodically the volt gauge drops to 11 volts for a period of time then later goes back up to 14 volt charging level. He has replaced regulator, battery and some other parts but has not solved the problem. Does anyone know what might be causing the problem? He is asking $4200 for the bike with 30,000 miles.

Thank you, Stephen