Bing carburettor problems

[Canoegeoff]

Hi I have a DKW w2000 with original Bing carb, I've just got it running well but on throttle shut down the engine revs stay high for a while unless I blip the throttle when it starts to settle down. It's not the cable sticking and I have fitted a new diaphragm. My Bing carb does not have a top Spring above diaphragm plunger ?? Should it have??
My vacuum box (which leaks) has been sealed and the carb port sealed. I can't see any air leaks.
Any ideas?
Cheers
Geoff

[kanonkopdrinker]

I had something similar with my 'oil-injection' W2000 Geoff a few years ago; never with the petroil one.

I wondered if it was the 25:1 mix that was lubricating the piston in the carb, absent in the o/I version?

Just a smidgeon of oil in with the fuel (Rotella 30 or 40, or Silkolene 2T I think it was) and the problem was cured. I wondered it there might have been a very slight high-spot of the piston causing it to stick occasionally? Not too much or your plug might foul.

David

[Canoegeoff]

Thanks I'll give it a try and post the result, I'm not sure how much a smidgeon is but get your drift.
Cheers
Geoff

[Canoegeoff]

Hi David
Just got around to adding a smidgeon of oil to the petrol & hey presto! The engine returns to idle speed!
Many thanks for that
Cheers
Geoff