The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: trolle on May 25, 2010, 06:13:07 AM

Title: Main jets, jets, idle jets and vacuum springs
Post by: trolle on May 25, 2010, 06:13:07 AM

Lately there has been a lot of discussions on the subject of carburettor tuning.

Having aquired two brand new left hand carbs from 1991 I became interested in the similarities and differences between carburettors used on the entire r65 time span from 1979 up to 1988.

The results of my "research" can be seen in the attached document

greetings from a lightly clouded and sunny north, but cold  >:(

Title: Re: Main jets, jets, idle jets and vacuum springs
Post by: nhmaf on May 25, 2010, 11:08:38 AM

Interesting, Trolle!

I know that BMW was continuously "tweaking" things with the carbs through most of the  70s and 80s, and have some of the differences indicated in the Bing carb manual, but your information shows even more  differences.  

Title: Re: Main jets, jets, idle jets and vacuum springs
Post by: Barry on May 25, 2010, 12:42:31 PM

That's a useful reference. The information on springs is something I've never seen before and seems to confirm that only the 79 - 80 flat tops were without them.

Title: Re: Main jets, jets, idle jets and vacuum springs
Post by: trolle on May 26, 2010, 02:25:19 AM

This article describes the functioning of the Bings very well IMHO:

http://www.omnilex.com/public/bmw78/cvcarb.pdf

greetings from a sunny north (viewed from the Olymp)
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fwww.suraklyn.com%2Fr65_forum_gallery%2Falbums%2Fuserpics%2F10004%2F2605.jpg&hash=6112eacf59b25208f823ec88cc2a17affc9aed4b)

Title: Re: Main jets, jets, idle jets and vacuum springs
Post by: Barry on May 26, 2010, 11:17:28 AM

Quote

This article describes the functioning of the Bings very well IMHO:

Yes I agree. It's one of the best I've seen and nicely explains the air premix in each of the 3 circuits