View Full Version : A fix for leaky float bowls?

06-04-2016, 08:25 AM
I had a problem with a leak on my 1968 CL175 float bowl drain screw. I tried a new washer, double washers and filed the flat surface on the bowl with no luck.
Then I remembered I had a bottle of "Supercoat" which is a fuel proof clear glossy coating for model airplanes to protect them form fuel spillage/leakage. I used it
originally to coat a very old cork carb float on my 1922 Mar Tan motor.

I coated the screw surface on the bowl then attached the screw/washer and coated the seam between the screw and the bowl twice with the coating.
Wallah! No more leak and it has been close to a month since I did it and I have ridden the bike often.

The bottle says it is a fuel proof coating and I believe it so far. It is a 4 oz. bottle made by the Sig MFG. Co. Inc. in Montezuma, Ia. Really! Montezuma, Ia.
American made. How refreshing!

I thought I would mention this as gas leaks on old motorcycles is not good. I hope it will help somebody else too.


06-04-2016, 09:55 AM
Great suggestion Dick. Along those lines; I have found that the food grade plastic containers they use for yogurt, cottage cheese, sour cream, etc. is just about impervious to solvents. I use those cups to mix all kinds of automotive paint, and for small part washing in lacquer thinner. I also have made seals, and washers for gas and oil lines.

T. Cotten
06-04-2016, 10:59 AM
Thanks for the tip, Dick!

I found a local dealer, and should be able to do an immersion test on etched glass once I'm sure the pumps are pure "summer blend".
And I sure hope its more durable than Aerogloss...


06-05-2016, 07:57 AM
Your welcome. Cotten, let us know what your test shows. So far I am really impressed with the stuff. Time will tell.


T. Cotten
06-10-2016, 05:53 PM
Uh Oh.... .. .. ..

..Uh... nevermind maybe..

Supercoat came off in strips from a test carb body.. but I think it was my fault for poor prep.
And frankly, coming off in strips is a good indicator that the coating itself is intact.

The glass test plate has only been in the pee for a day,.. but looks good!

Everything else that usually fails already has, and everything that usually survived (JBWeld, Red Cote, "The Right Stuff" which shouldn't, and my "secret sauce") has survived as well, so far.

This is the first test for Gorilla Glue, and its beating its chest successfully.


T. Cotten
06-12-2016, 02:30 PM
2016 Central Illinois P4test in progress..

Supercoat is doing well! So is Gorilla Glue.

And so are Red Cote, my 'secret sauce' (of course), "The Right Stuff" (which isn't supposed to...), and seasoned JBWeld.
JBWeld just a few days old lifted from the glass, again.

'Original' Pliobond survived previously, but the new Pliobond 25, not so well.

Everything else that always failed has, except one: Gasgacinch did better this year, so far.
So once again, its all about the ever-changing fuel, not the goober.

Your results may vary.....


T. Cotten
06-12-2016, 06:03 PM
Damn science is hard.

Gorilla Glue was doing great until I showed the glass plate to a local visiting from the tavern across the street.
He promptly picked it off with his fingernail.

So now I have prepared another sample,
and must add “adhesion” to the list of variables.


06-13-2016, 09:09 AM
Thanks for the update. I'm still leak free.

T. Cotten
06-13-2016, 01:31 PM
The Supercoat is so far fuel-resistant, Dick,

Fuel-proof requires a spotless record over years and various fuels.

But not only is it hard to apply (Second coats wash off the first), it doesn't adhere very well.
Still, its as good as the VHT I have been using. However, the ability for my customers to touch up down the road with the same paint may be lost.

The instructions say to have a smooth surface, which is a "given" for a potmetal Schebler, but I fear mill-profile is critical. Even beading the outside of bronze bodies may not be enough, and I must turn to ALOX, and add yet another masking step.

So far, my local BP (with "Invigorate" ha ha) seems far less digestive than local fuels for previous years.
(Rats! I need fuels to get REALLY bad, like 2006, if I want to outrun my competitors.)


06-13-2016, 06:38 PM
I have been using EZ Lube which is an aircraft petcock sealant and have been very pleased.

T. Cotten
06-20-2016, 06:03 PM
"EZ Lube" is something I would have to go to the Big City for, I guess, Bob!

(Something I avoid...)

SIG "Supercoat" is doing GREAT in my P4gas immersion test, Folks!

Its been a week or so, and some of the goobers are finally getting soft. Gasgacinch did better this year than others, but is
now getting snotty. Bondo Muffler and Tailpipe Sealer seemed surprisingly resistant, and I considered it a candidate
for inlet nipples, but its now softening. My years-old application of Caswell's might as well come out so I can save it
for next year's test.
VersaChem "Mega Black" RTV is snot, and my 'secret sauce' is still fuel-proof.
Pliobond 25 isn't quite as good as the original.
I forgot to test 3M #800 and Seal-Lock, but there is still time, if I can find my tube.

A red and a green Loctite used to glue two plates of glass together didn't make it through the night.

Red Cote (no surprise) and "The Right Stuff" (which should fail) are untouched.

The one-week seasoned JBWeld continues to lift off the glass, but the well-seasoned gob next to it is un-fazed.
And last but not least, Gorilla Glue isn't softening, but it is lifting from the glass. I am as disappointed as anyone,
as it seemed like the perfect adhesive to suggest for locking floats to the lever.

More as it deteriorates...


T. Cotten
06-23-2016, 07:13 PM
Glyptal failed, again,.... Folks.

Motor cases shouldn't encounter much fuel, unless you have an OHV with a leaky petcock.