Bings, 40mm constant vacuum

**John Roberts** · #1 28 Feb 2005

Can anyone tell me what the tiny little spring clips at the bottom of the float needles are for? Blowed if I can see. If they get a bit out of position might they be the reason for the floats ocassionally sticking and flooding?

Also, has anybody found the main jet holder to be tight in its seating, I've just taken both of mine out to change the needle jets. They were horrendously tight, and they were both extremely tight to screw out, altogether a harrowing business. I had visions of the thread being wrecked as they came out, but both the bodies and the holders were ok. I did use a bit of localised heat (LPG and a small burner) before they budged. No, I didn't knacker the o-rings.

So, wise ones, how should this job be done, or were mine tighter than other people's?

Thanks,

John

**Grant Johnson** · #2 1 Mar 2005

Sounds like they haven't been apart in far too long! Annual is not a bad idea, both to make sure thy're clean and to prevent this exact problem.

REPLACE ALL O-RINGS!

The spring clip "hangs" the needle on the tang on the float - forcing it to drop down when the float drops, preventing the needle from sticking shut.

Flooding is the opposite problem. Usually needle sticking open. Can be caused by float levels too LOW - allowing the needle to cock off to one side slightly. Or dirt in the fuel, caused by owner neglect... Clean the fuel petcocks filter out, and put a small auto filter inline as well to each carb. I've been running inline filters for 20 years and never had a float stick. May or may not be related!

hth

Grant

**John Roberts** · #3 1 Mar 2005

Ah, dearie me, where would I be without you, Grant? It wouldn't have ocurred to me in a million years that they were there to pull the needle down! And, yes, I'm sure it's possible that the ocasional flooding could have been due to their being incorrectly fitted. I'll see how it goes and post the result for the good of all.

Thnx

J

**John Roberts** · #4 12 Nov 2005

Well, it took a little while, but as promised I'm getting back to you to say that the flooding has stopped. Well, nearly. My left foot isn't getting its occasional soaking in petrol and things have certainly improved but I'm getting a little rough running recently and there is a slow drip from the left carb when I park the bike, a drop every, um, ten seconds, perhaps. The float valve is newish, two years at a guess, and I'm wondering if there is anything I could do to the valve seating to improve matters. It does appear to be part of the body of the carb and not replaceable, i.e. it doesn't seem possible to screw it out and and screw a new seat in instead.

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Johnefyn

**Grant Johnson** · #5 12 Nov 2005

Can't do much to the seating - just replace the valve - which I would do at this point - newish not withstanding. If it doesn't fix it you've got a good spare

Then I'd be very sure I had the float level right. It does need resetting once in a while - as the needle wears even slightly, the level does change.

The seam on the float should be dead level with the float bowl seat / gasket surface.

good luck,

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Grant Johnson

Seek, and ye shall find.
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One world, Two wheels.
www.HorizonsUnlimited.com

**Grant Johnson** · #6 12 Nov 2005

re rough running - as any good mechanic will say, quote: How long since the last service? That long? It's time!

A thorough carb clean, new plugs, lube the throttle cables, new air filter and an expert carb balance works wonders on the airheads.

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Grant Johnson

Seek, and ye shall find.
------------------------

One world, Two wheels.
www.HorizonsUnlimited.com

**chasbmw** · #7 5 Mar 2006

I would add that a carb rebuild is needed every 5 years or so, this would include new diaprams, replacement of the various o rings and gaskets, does wonder for a bing.

Charles