Intermittent carb bowls overflowing

[Bill-H]

How odd..
R100GS '89, 35,000 miles
Sometimes, after bike has not been used for a few days, when I turn on the petrol taps, prior to starting the bike, the carbs overflow, usually the right-hand one, but today both were at it, petrol running out of overflow at quite a rate.
I put in-line filters on a few months ago because the bike had been stored the best part of 15 years, and there was some red paint flakes getting through, but that was 2,000 miles ago, and after the first filter change, they have remained clean since.
The bike was recommissioned in March of this year by Blue Bell, and runs well, starts easily etc.
It doesn't always happen, and only seem to do it after a few days not being used.
I remove the float bowl, and lift the float a couple of times, reassemble and all is well.
As I say it doesn't always happen, and doesn't happen when the bike is in use, even when the taps are left on all day with the bike outside my house.
I can but assume that some petrol must evaporate when the bike is not used, and that the floats stick part-way open. There's no leakage evident when the bike is not used.
It's always left on the centre stand with the taps off, happens whether tank is full or near-empty.
I could understand muck stuck in carbs if it was always doing it, but it doesn't happen very time, and bowls are clean when I look !
Starting to annoy me now.
Grrrrrr.........

 

[MickDB1]

Put some new rubber tipped fuel needles in Bill

should sort that one out

 

[Bill-H]

Cheers Mick !!

 

[alimey4u2]

While you're at it, dunk the float in hot water & look for bubbles or surface bloom...

 

[BillN]

Take the bowls off make sure the floats move freely and blow out the bowls with compressed air

Simple compressors are cheap and worth their weight in ?

 

[Voyager]

I have been told that this was a common complaint with the older Police bikes.

A good whack with a truncheon usually sorted it.



Bob.

 

[Sergeant Pluck]

I had the very same problems on my R100/7 and it drove me nuts trying to figure out what was going on - cleaning the carbs many times, setting and resetting the float height etc, etc. It wasn't until I removed the inline filters that I fitted previously that the problem cured itself.

I still don't quite know what was going on, but in my case it was definately the filters that caused the problem.


Pluck.

 

[alimey4u2]

Truncheon smite, inline filter removal could only be explained by a trapped air bubble on the seat. Liquid tension aiding compromised sealing...