Carb sealing

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meowy84

Member
Jul 18, 2009
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Assembling my engine and I already see that I'll probably need a way to seal the carb to the intake tube to avoid air leaks. Any suggestions?

I know some of you have used silicone sealant but obviously that would have to be done on the outside of the tube/carb joint and I want to avoid the messy-silicone look. I know that some of the websites also sell an O-ring that's fuel resistant that seats on the little ridge in the carb entrance. I'm leaning towards ordering one but I hate to wait. So I checked my local plumbing shops and they have tons of the right size O-rings (3/4" diameter) but of course they're rubber and so not so good for fuel. Even if I use just a regular rubber O-ring and have to change it every couple of weeks when it degrades I could live with that. Any other options?

What solutions have you guys used?
 
charles.paskell

charles.paskell

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Feb 25, 2010
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I would steer clear of a permanent weld like application those rubber o rings sounds like the way to go also you could seal it with a couple wraps around it with electrical tape
 
2door

2door

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Sep 15, 2008
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I'm not a fan of the 'O' ring method. The rubber will swell and begin to deteriorate quickly. You don't want your engine injesting that stuff and it isn't a good seal because it cannot be clamped in except with hand pressure against the carburetor while installing it. Several members have also had the 'O' ring come loose and get sucked into the engine. Not good. Some suppliers offer a flat gasket, gasoline compatible, that will work better than standard rubber 'O' rings. I think you'll find that most silicone based sealants are not compatible with gasoline, (says so right on the package). There are some sealers that will do the job and if done correctly will not look like heck. When using a paste type sealant you want to fill the gaps (slots) where the throat of the carb attaches/clamps to the intake manifold as well as the entire surface of the intake where the carb goes.
This product is a little harder to remove but I've had good luck with Seal-All. It is a clear semi-liquid sealant and will take gasoline. Good luck. Let us know how you do.
Tom
 
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meowy84

Member
Jul 18, 2009
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Canada
2door said:
I'm not a fan of the 'O' ring method. The rubber will swell and begin to deteriorate quickly. You don't want your engine injesting that stuff and it isn't a good seal because it cannot be clamped in except with hand pressure against the carburetor while installing it. Several members have also had the 'O' ring come loose and get sucked into the engine. Not good. Some suppliers offer a flat gasket, gasoline compatible, that will work better than standard rubber 'O' rings. I think you'll find that most silicone based sealants are not compatible with gasoline, (says so right on the package). There are some sealers that will do the job and if done correctly will not look like heck. When using a paste type sealant you want to fill the gaps (slots) where the throat of the carb attaches/clamps to the intake manifold as well as the entire surface of the intake where the carb goes.
This product is a little harder to remove but I've had good luck with Seal-All. It is a clear semi-liquid sealant and will take gasoline. Good luck. Let us know how you do.
Tom
Click to expand...
Thanks for the input Tom. It did dawn on me that the O-ring or bits of it could get ingested so I thought I could make a little sleeve out of soda can aluminum to fit inside the intake tube and protrude ever so slightly beyond the end of the intake tube that should stop the O-ring from being ingested. The bend in the intake tube would stop the other end of the sleeve from trying to slide into the combustion chamber. Additionally the soda can aluminum is so thin that the effect on airflow should be virtually nil. As for silicone I was more leaning towards some of the auto gasket makers which have the consistency of silicone sealant (I should have been more precise) that are typically oil/fuel resistant but I remember most being red or blue which I wouldn't want to goop on the outside because of their looks.lI might try Seal All though as you suggested since it's fuel proof and clear in color so it won't be so noticeable.
 
Bikeguy Joe

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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If you are having a problem getting the carb on enough to cover the "slots", I grind some of that end of the carb off with a belt sander.
 
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