Started the R 42
Posted: Thu Mar 08, 2007 8:19 am
Yes, these motors are noisy. I believe it's the gear train in front. The idler gear is on an eccentric bolt that was set at the factory and then pinned. If there's any wear, then the connections between the cam and magneto gear get loose. Slabon and Knittel refer to this in their Buyer's Guide when they talk about the changeover to chains in one of the later series of R11s.
But it shouldn't vibrate particularly. It is a boxer, and with a single carb, there's no balancing to do here. I would think it would point at the valves not being set right or maybe a decaying wire or plug on one side.
And of course, "revving it up" is relative, these motors only go up to something like 4,000 rpms.
I think Fred Jakobs wrote that there was some evidence of BMW having looked over a Douglas pretty closely, even before the M2B15 was developed.
But it shouldn't vibrate particularly. It is a boxer, and with a single carb, there's no balancing to do here. I would think it would point at the valves not being set right or maybe a decaying wire or plug on one side.
And of course, "revving it up" is relative, these motors only go up to something like 4,000 rpms.
I think Fred Jakobs wrote that there was some evidence of BMW having looked over a Douglas pretty closely, even before the M2B15 was developed.