R26 variable idling

Begonnen von BSA Bob, 15 November 2022, 03:32:03

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My R26 is now running, but the idling is poor. It varies in speed from OK to quite fast even with a closed throttle. If the throttle's opened & then shut the speed takes a long time to slow, sometimes it doesn't slow at all. It seems to get worse as the engine heats up. The carburettor's a Bing 1/26/93 with an accelerator pump.
The idling controls on the carburettor are set OK & the engine's been static timed.
Can someone help with ideas?



Sounds like a worn throttle slide causing too much bypass air past the closed slide
Zündapps sind für mich die besseren Boxer



may be or not, this is the first time, in my over 40 years involved with BMW, I saw this problem.

But why not.

Zitat von: rolf.soler am 15 November 2022, 09:30:03check out this well known problem:
Zündapps sind für mich die besseren Boxer

Kurt in S.A.

Does the slide freely move up and down in the bore?  With the engine not running, does the slide return to the bottom when the throttle is released?  I recently replaced the return spring inside the carb of my R25/2.  It appears that the original one was sacked.

Kurt in S.A.


Zitat von: Elefantentreiber am 15 November 2022, 10:13:31may be or not, this is the first time, in my over 40 years involved with BMW, I saw this problem.
maybe you work to little with one-cylinders ? ;D
There's is quite a number of people who had to fix the "hochgewandernter Mischkammereinsatz"
and it causes precisely the problem of difficult idle setting


Thanks for these replies.
The slide doesn't have any noticeable play & returns to the bottom of its travel. Fortunately there's no sign of the problem mentioned by Rolf. I thought it may have been a vacuum leak but spraying WD40 & gas over the jointed areas did nothing.
But something seems to've gone right. I stripped & cleaned the carb again using cleaner & compressed air, & also added a bit of oil to the centrifugal advance. So far this has fixed things with the revs dropping properly & a consistent idle.

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