Boxerworks.com

Greetings all,
Recently picked up 2 airheads (1970 r50/5, 1973 r75/5, plus an r60/6 Motor). Been wrenching on all things internal combustion for a couple decades now. Have owned several antique, vintage cars, mc’s. These are first. BMW’s. After cleaning out the mouse house’s, soaking cylinders, now seeing if I can get spark. I’ve read a lot on various sites and know the following: 1970 r50 - By jumping starter relay, engine spins. I have 12 volts at coils, 12 v at live side of points. Ground side of points is at ground. New condenser, new points. No spark, however, if I I manually open/close points I get good spark at spark plugs. With battery disconnected, if I measure across points I’d do see they are opening and closing. I am stumped as manually opening closing points I get good spark. Would think with starter running would see same. At this point I am not trying to get the engine to run, just want to see spark at plugs.will then figure out timing etc....
Thanks for any suggestions.

Welcome! Do you have the proper point gap? Supposed to be about 0.016". Is the timing showing the S-mark in the timing window when the points open? You should be able to see 12v at the coils disappear when the points open...the S-mark should be in the window.

Be careful to have the spark plug threads grounded to the engine anytime you're check for spark. If the spark, when it jumps the gap, can't find a path to ground, you have the potential for feedback into the coils which can damage them.

Kurt in S.A.

Ok, so right after I posted above, went back into workshop as what I said made no sense. Turns out when I was fiddling with points, I’d didn’t put the little nub into hole correctly on Timing plate. Now have great spark.
Now on to timing and seeing if she wants to fire.

Welcommen.
Glad to help

Thanks for the info, next issue is getting the timing advance unit off. Took nut off (read about not over tightening when putting back on) but the advance does seem to want to move. I was hesitant about pulling too hard. Should you need some sort of puller?

Also it seems the timing plate is stuck. Loosened (removed even) the 2 screws at 12 and 6 oclock. Plate does not want to rotate. This bike sat for many many years in a garage before I got it with most cavities filled with mouse nests. How easy should the timing plate move. this is a 1970 R50/5.

Try a penetrant and let time work on it. The advance unit is generally a loose fit...I wouldn't get too aggressive with force to remove it. As for the round timing plate, likely some corrosion has built up...that's not good for grounding of the plate.

Kurt in S.A.