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  View original topic: Carb Question ... mixture bypass valve
Kaput Sat Mar 13, 2004 7:44 pm

Hello,
After a long while of carb trouble I found that the mixture bypass valve was clogged. I was wondering if it is dangerous at all to drive or run the bus with this valve partally unscrewed untill i can get it cleaned out.

Can anyone tell me what exactly it does and possible ramifications of not getting it fixed. Runs 1000% better unscrewed.

-=dan=-

Kaput Sat Mar 13, 2004 8:37 pm

http://www.acvw.com/images/tech/8/30pict.jpg

AKA Pilot jet cutoff valve 26 in this diagram

Kaput Sat Mar 13, 2004 9:02 pm

Think I founbd the answer to my own question. That valve is ment to be adjusted. So sad to think that half a turn of a screw could have saved me so many hours.

Kaput Sun Mar 14, 2004 2:54 am

please tell me if i am wrong. just had a post telling me it was an electrical valve that could set my bus on fire in the engine forum. (not electrical at all) In fact my carb has been dissconnected electricly as reccomended by JM.

Amskeptic Sun Mar 14, 2004 2:01 pm

The cut-off valve also serves as an idle jet. Yes, you can get better idling by loosening, but it is only hiding the cause of the lousy idling when it is properly seated. The wire that leads to the solenoid will, in most cases, prevent it from backing out all the way, but it does introduce a vacuum leak there as well as dump more fuel in. John Muir has many opinions about what is best for your VW, including tearing out all of the electrical wires and the choke. But they are only opinions. He would be stunned at the advanced knowledge of air-cooled VW fiends in today's world. You do want to check the jet size engraved on the solenoid, you do want it securely fastened, and you want a clean carburetor with correctly adjusted float, and correctly adjusted valves and ignition timing to help you track down driveability issues.
Colin



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