my carb...

Jneff · May 15, 2011

I've got a skyhawk 66cc motor and i'm having a problem with the carburetor vibrating loose and falling off. i've tried lock tight, tried replacing the nut and bolt that hold it together but it still vibrates loose and falls off after about 5 hours of use. --i've resolved to tying bailing wire around the motor, carburetor and frame to hold it together...
has anyone else had the problem or have any advice? thanks guys.

DaveC · May 15, 2011

This might be a case where you want to smear a bit of RTV silicone sealent on the intake pipe and the clamping surface of the carb. Thin layer, very thin. The RTV will "roll" up in front of the pipe, forming an O ring. That's why too much is too much.

Do this late in the day so the RTV can set up overnight. It should hold together and yet you'll be able to remove the carb if you want. If you have to. Just clean the old RTV off and start fresh.

2door · May 15, 2011

This not a common problem. Carburetors falling off or coming loose from the intake manifold isn't something we see a lot.

What carb do you have? Is there a plastic liner in the throat or is it a metal to metal attachment?

Did you mount the engine solid to the frame or are you trying to use rubber somewhere in the mounts? If so, get rid of the rubber. It doesn't eliminate vibrations but concentrates them to the engine and fasteners.

If all else fails you can try a product called Seal-All. It is a gasoline resistant sealer/adhesive that will seal as well as 'glue' the carb to the intake. It requires a clean surface to work so make sure the carb throat and manifold are oil free. Use it sparingly. Roughing up the surfaces with sand cloth or a wire brush also helps the adhesion.
Disassembly is a little difficult but it will come apart if the need arises.
Seal-All is available at most auto parts stores.

The reason I shy away from silicone based sealers is because most of them are not resistant to gasoline (read the labels) and will soften over time and turn to goo.
Good luck.
Tom

Jneff · May 16, 2011

hhmm, i didn't install the engine myself, but there is no rubber anywhere...
you said it's not a common problem and i've heard that before, haha, trust me, i have the worst luck with computers, cars, anything electronic or with an motor, the story of my life is hearing people say "in all my years of experiance, i have never seen this"
-- i will try the seal-all and if that doesn't work, i clicked on the pirate cycles link and they actually sell an intake valve that they say is designed just for this problem.
the carb i have is the high performance CNS that came with the grubee kit.
when i first bought the bike (already assembled) it was metal to metal. i used wire to hold it together, and i took it to a guy to get a better chain tension thingy installed and told him about it and he put -something- to seal it and replaced the nut and bolt. it rode for about 5 hours, then it fell off again and the sealer kinda just crumbled.

adam valentine · May 16, 2011

i had air leak with that carb but never fixed it bought an nt carb and yep it fell off going down road tried seal all did same thing so i called duane with that dax oh yea did the o ring thing also he told me do o ring seal all and biggest dang Phillips head i could find and clamp down i owe my success into using real big good Philips to my success check out your tools

recon chris · May 24, 2011

I have the same motor and the same problem. It won’t matter how much you tighten the bolt or what type of "sealant" you cover it with it will fall off always. Even worse is that before it falls off you can bet its leaking air and leaning out your air fuel mixture shortening engine life. the only way to fix this problem and know that it will NEVER fall off or LEAK AIR is to take a large hose clamp (home depot 2$) and clamp the carb to your engine. To do this run the clamp from the frount of your engine around the back of your carb and screw it tight. DONE

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