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-   -   Airhead Carb-float Help (http://www.horizonsunlimited.com/hubb/bmw-tech/airhead-carb-float-help-8089)

GuinnesS 21 Aug 2004 02:54

Airhead Carb-float Help
 
I recently purchased a very sweet 88 R100GS and it is now seeing more sunlight than my latest and greatest Uberoilhead. However, the previous owner had converted the float system in the carbs to alcohol-proof ? floats. Well every now and again the left carb bowl starts overflowing and spillind out on the street. Removing the bowl, pouring out the excess fuel back into the tank and then replacing the bowl usualy cures the problem... for a while. So what gives? is there an easy fix or should I just replace with stock float system?

Grant Johnson 21 Aug 2004 05:46

It's one of several problems -

1. float level wrong - make sure the brass plate is absolutely level when the float needle is just closed.

2. Float needle worn and sticking.

3. Float itself is sticking against the bowl. Early versions of these tended to stick a little. If it is sticking, file a VERY slight bevel along the edge that hits the float bowl to give it a little more clearance.

I had these on my R80G/S for over 120,000km, worked fine all the way.

Float needle is the most common problem, and most people don't replace them often enough. ANY sign of ridge or groove on the red rubber seat is grounds for replacement. You may even need a magnifying glass to see it.




------------------
Grant Johnson

Seek, and ye shall find.

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One world, Two wheels.
www.HorizonsUnlimited.com

GuinnesS 21 Aug 2004 12:12

WOW! That is a wealth of knowledge. Thank you for your prompt response.

John Ferris 21 Aug 2004 22:12

With the dual float kit the floats work independently of each other. There is a part that acts as the hinge with a tab that moves the float needle. It is brass I think.
The bottom of the float needle can wear a hole in the tab. It is easy to replace.

pif 25 Aug 2004 08:40

I had these when i bought my gs and swichted them back to the stock ones. They are a little bit to tricky to make them working fine. The stock are working just fine to me.
good luck.
pif.

John Roberts 8 Nov 2004 20:18

I've had a lot of trouble with sticking floats on my '82 RS, it all started when the inside of the fuel hoses crumbled into tiny little cubes of rubber which prevented the float valve from seating. This happened a few times, I always opened the fuel taps briefly to flush any bits out after first removing the float and allowing the valve to drop out. Eventually it dawned on me that there weren't any more bits of rubber,or, indeed, any other debris getting flushed out (I was catching the flushed fuel in the float bowl and then returning it to the tank after taking out the bits) Well, it cured the problem for a while, so, what the heck, you know how it is...

Anyhow, last month as I was going through the performance for the umpteenth time (and having in the meantime installed new needles) I noticed some rough marks on the hinge pin on which the float pivots, and I remembered that they must have been caused when gripping it with a pair of pliers in the middle and sliding it out of its supports to release the float. As the sticking float was a recurring problem I had been puttng the pin back in a slightly different position with about 2mm of its end protruding to allow be to grip it and extract it with the pair of pliers more easily, with the roughness on the pin in its new position making the float stick. So after putting the pin in the electric drill and lightly holding a small file against it before replacing it it does look as if the problem has been finally resolved. It's been ok for about a month, so perhaps it might be worth you checking your pins for roughness
Good luck
John


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