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Thread: Installing an overflow pipe into the carb bowl Reply to Thread
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  Topic Review (Newest First)
09-07-2019 08:02 PM
pdwestman It is not just a 'Kawasaki thing', its ALL street legal bikes, at least in the USA. It's an EPA thing!

The EPA would rather have the owners get their drippy / poor running machines properly operating / repaired, rather than continuously dripping raw, evaporating fuel everywhere & every time they travel.
09-06-2019 09:37 PM
klr4evr I used Seal All to seal a leak in the fuel tank of my old 65 Impala many moons ago. Never had an issue thereafter.

Don't know why Kawasaki wouldn't install overflow tubes in all their carbs. The Concours 1000 had a number of hydro-lock engine failures when the fuel petcock would fall and the carbs would overflow into the cylinders. Guy in Florida made a business of retrofitting the carbs with overflow tubes.
09-06-2019 07:00 PM
Tom Schmitz The overflow pipe can extend .6" above the gasket line of the bowl before it interferes with anything, so @pdwestman's .34" figure is safe.

The bowl is 1" deep.

.34 extension+.14 counterbore+1.0 bowl depth = 1.48". I'm going to make the pipe just a bit longer than 1.5" so that I can trim it to the .34" extension when I am finished. The pipe is made from 1/8" brass tubing with a 1/64" wall.

I decided to use Seal-All because it is supposed to be made to be resistant to gas, alcohol, oil, etc.

I flared the end of the pipe just a few thousandths of an inch so that it would be a light press fit into the counterbore.

The pipe had been roughed up a bit already; I roughed up the top of the boss to give it some tooth and clean it. I put a band of All-Seal around the pipe and tapped it into place and squared it up.

I'm letting it cure until tomorrow and then I'll test it for mechanical strength. If that's OK I'll set the carb up with a bowl full of fuel and set it aside for a week to see if it leaks and if the All-Seal holds up.
09-06-2019 06:43 PM
Tom Schmitz
Installing an overflow pipe into the carb bowl

I figured that if I was doing one overflow pipe I might as well do two and took a look at the pumper carb bowl to see if it was possible.

The boss is there.

The necessary drilling has not been done, though. I would need to drill two holes and plug the entrance point of one of them. Not today!

Here's the normal bowl. Same boss and drilling straight through will come out at the nipple.

The first drill matches the inside diameter of the overflow pipe at 9/32".

The second drill creates a counterbore just a bit deeper than the diameter of the pipe, 9/64".deep.

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