Vintage BMW Motorcycle Owners

Managed to find the time to pull the carbs. Not a full dunk/soak kind of thing but broke them down enough to get all the key parts with some carb cleaner spray. Started with the left one where there didn't seem to be any issues. Nothing really unusual to be seen. Over to the right side, the pinging side, again nothing that jumped out at me.

There was one thing, though. The air screw was set at 1-1/2 turns out on the left side but was 2-1/2 turns out on the right side. Hmmm...wonder how/why it got that way. I did use the EMPI vacuum gages the last time I was synching things. But if the right air screw was a full turn out more than the other side, that might make it run a little leaner which could lead to pinging. I know that there are separate regimes of carburation depending on throttle position, but even the idle circuit is contributing all the time, although maybe to lesser amounts with more throttle. Hmmm...

Anyway, I took the bike out and...wait for it...no pinging!! I kept listening for it in the situations it happened last time. I didn't push the bike any harder than normal. So I'm cautiously optimistic that I took care of something during the cleaning. I'm still scratching my head on the air screw differences, so I might need to revisit that and/or resynch the carbs.

So, thanks for the carb suggestion. That might have been the ticket!!

You don't set the mixture screws with the gauges. Just by ear with one cylinder running at a time. Find the highest idle for each cylinder and then go a bit richer (inward). Each cylinder should come out approximately the same turns out when you're done. A base setting of 2-2 1/2 turns gets you pretty close.

But you seem to have it pretty close now. Glad you found it!

Dave

Good advice, Dave! That's how you get each cylinder idling at its best. Thanks...