Carbs float height

Re: Carbs float height

Postby sneck » Mon Jan 09, 2012 5:48 pm

I have stripped my carbs down again and checked a few things out as suggested,
I have checked out the overflow standpipes for leaks by squirting carb cleaner up the overflow pipe and covering the standpipe with my finger and no leaks have appeared.
Image
I have put the floats on the scales 5 (five) of the floats weigh 8 grams ,
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but 1(one) of the floats weighs 10 grams,
Image
shaking the float about doesn't seam to indicate any fuel inside.
Luckily for me my mate who lives 1/2 mile away from me has several carb spares including some spare floats and I have found one that matches the others at 8 grams.
The carb with the 10 gram float was one of them that was causing problems so hopefully things could be looking better on the next rebuild.

Thanks for your help and suggestions guys you have helped me no end.

Sneck
Last edited by sneck on Tue Jan 10, 2012 5:50 pm, edited 5 times in total.
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Re: Carbs float height

Postby NobleHops » Mon Jan 09, 2012 6:17 pm

This is no help but for sure, thanks for keeping this topic updated. These problems and solutions become the knowledge base that many many people use, even if they don't post. I see the site traffic, it's priceless content. Thanks Sneck.

N.
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Re: Carbs float height

Postby oldschoolcarbs » Wed Jan 11, 2012 1:22 pm

Sneck, BRILLIANT! To my eyes this is a marvelous revelation.

When I read Bobber's suggestion to check the weights I had a moment of skepticism, but I have to say that this is such a wonderfully unexpected observation that it's spurred me to begin checking weights. Our ..."jobs" as professionals, so called, makes us acutely interested in any variable that we can anticipate and thus eliminate. I'm truly awed that you actually found a heavy float, which naturally is going to be less buoyant and tend to overfill. Bravo to bobber for asking and to you for not being an "expert" (read: assumption-making know it all)! Of course this could eventually be rejected as the root cause but it's invaluable nonetheless. Either or both of you get a set of new pilot needles for your efforts. PM with your info (or use *****@yahoo.com) and I'll send them out.

RE, overflowing, let's be clear on the symptoms.

A weeping float, whether due to seat, needle, or **soggy float(?)**, will fail to seal off the flow of fuel into the carbs. With nowhere to go the gas level will rise to the point where it will 1) reach the top of the overflow standpipe and run out through the drain tubes or 2) exit upwards into the throat of the carburetor and from there will obey Newton's laws of gravitation. I've seen both inundated air cleaners and gas-filled combustion chambers. Which scenario depends on how the bike is situated. Resting at a critical incline will locate the top of the standpipe higher than the next lower point of exit and you'll have a catastrophic leak.

A cracked standpipe, on the other hand, will weep fuel out through the drain tubes and NEVER rise into the throats by simple reason of the fact that the bowl is draining before the float lifts far enough to shut off the flow. Think: leaky toilet.

Gas in the throat(s) eliminates the standpipes by default. (This is NOT to suggest that one should fail to verify their soundness as a matter of course--one could be clogged OR cracked.)

If I could prevail upon you to run one more simple test, leave the heavy float in the sun and see if the weight decreases. This will tell us if there's fuel inside or if it's simply defective.

Thanks again for being such an adventuresome sort.
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Re: Carbs float height

Postby sneck » Wed Jan 11, 2012 6:37 pm

Thanks for your positive comments ***** I am just an amateur at this game.

I joined this forum for help and advise and all I have done is to take note and try whatever advise was given to me its the other members that have posted that have given me the inspiration

One day you never know I might be able to take these carbs apart blindfolded LOL.

I will try your suggestion with the heavy float, but after another night in the garage it looks like my float needles/valves are leaking over a period of time so it looks like I will have to look around to see who sells these things


Thanks Sneck
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Re: Carbs float height

Postby oldschoolcarbs » Wed Jan 11, 2012 10:06 pm

Sneck, send me a PM or email. I just got in a stocking order. I'll let you have them at cost.

Jack
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Re: Carbs float height

Postby bobber01 » Wed Jan 11, 2012 11:24 pm

Thanks for the offer ***** however I'll pass. For the info/assistance I've gained from this forum and its members it wouldn't feel right. Just content finally feeling as though I contributed something.
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Re: Carbs float height

Postby oldschoolcarbs » Sun Jan 15, 2012 1:21 pm

I just had to know what was going on here so I sacrificed a float.

I've always known that they're made of some sort of closed cell foam but sneck's findings made me wonder if they're subject to capillary infiltration through a surface crack.

So, I cut one in half and weighed the pieces, then soaked them overnight in gas. No change in weight, so either it takes a long time for them to become laden with fuel or sneck's heavy float is *merely* defective.

While I was at it I tested about thirty floats and found them all to be within .1 gram. Now I'm rigging up a way to investigate how much weight it takes to fully depress the float needle plungers from varying sources' goods. THIS is where I think some real problems lie because they can become internally corroded (or be the end result of not-so-meticulous quality control) whilst looking outwardly perfect.

4964

4965
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Re: Carbs float height

Postby sneck » Mon Jan 16, 2012 3:53 pm

Hi there *****

I never were knew they were foam filled I thought they were hollow

***** wrote:If I could prevail upon you to run one more simple test, leave the heavy float in the sun and see if the weight decreases. This will tell us if there's fuel inside or if it's simply defective.

There is a lack of sun at the moment over here in the U.K ( can you ship some over from CA) so I have had the 10g float on the heating radiator for a few days and it now weighs 9 grams but will keep you posted

thanks Sneck
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