Help! I can't get the timing right on my R90. Even if I have the points plate retarded as far as it can go, the timing is still too far advanced. Could the timing chain have slipped? Is there something else it could be?

Yes. You have the points gap set too wide. Set at .016", and measure it with the feeler guage that came with the bike, bent to a 45 degree angle, or grind a standard automotive feeler guage til it's about 3/8" wide, and 2" long. make a 45 degree bend, about 3/4" from the end. Now take a fine Arkansas stone and clean up all the burrs on the edges all the way around.

Use this to set the points gap so that the feeler guage will stay in there without holding it, but one touch looser makes it fall out. Got it?

To set the timing, disconnect the points wire to the condenser, and connect an ohmmeter or test light to the points wire and ground (for the ohmmeter) or to the battery positive terminal (for the test light). Using a 6mm allen hex key in the alternator bolt, with the spark plugs removed, rotate the engine in the CLOCKWISE direction (as viewed from the front) until the test lamp comes ON, or the ohmmeter indicates 0 resistance. The points are closed at that point. Now look in the timing hole above the left carb. Keep turning the engine CLOCKWISE as you look at the flywheel and the lamp or ohmeter. As the "S" Mark on the flywheel (the line, not the letter) passes the notch in the crankcase, the lamp should go OUT, or the ohmmeter should indicate INFINITY. That's correct idle timing. To adjust, move the entire points backing plate by loosening the two retaining screws.

Reconnect the points wire at the condenser, and make sure the rubber tube is secured in the notch of the points chamber, before starting the engine. Check the full
advance timing at 3200 RPMwith a timing light, looking for the "F" mark to line up in the timing hole.

I seriously doubt that anyone would ride a BMW boxer until the timing chain was so loose as to make setting the timing impossible. The noise would be deafening, or at least real annoying. (Well, I know one guy who's riding an RT that way right now, but he says he's gonna fix it, so I won't name
him.)

I don't doubt that you know how to do this already, but I'm really tired of saying "set the points" and getting 50 off-list emails saying "How do I set the points?", so I just laid it all out to start with.

-Tom Cutter

(Originally posted to the Airheads list)