Vintage Dirt Bike Q & A

Hey guys,
I have an old mikuni carb that is leaking from the base of the overlow tube. The fuel leaks out of the overflow nipple. If I take off the bowl and fill it with gas (the overflow tube sticking out of the fuel), it will all leak out of the nipple. I want to repair the leak and can't decide if I should use solder or an expoxy. I guess I could always block off the nipple as well.

I would be soldering a brass tube to the aluminum bowl. Does anyone have any opinion on the solder vs epoxy question?

It took a while to figure out where the leak was coming from. I swapped out the float needle and seat. Set and reset the float height and even replaced the floats. When it was still leaking, I knew it had to be something unusual. Sure enough!

thanks,
nola_fiddy

I believe JB Weld epoxy is completely gasoline-resistant, and readily available - it would be my first choice to fix that kind of leak.

There's also something called Durafix, which I have no experience with:

http://durafix.com/

There are also aluminum-compatible solders, which was news to me.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

Thanks for the reply Ray. I did try to solder the leak this weekend using a pencil butane torch and regular silver solder. I was not able to get the aluminum and brass hot enough to get a good solder. I am a little uneasy using my propylene torch. I don't have a lot of experience with soldering and don't want to melt anything.

I am going to clean it all up again and use J-B weld. It should work but may not be as long lived a solution as solder. I'll post my results when done.

nola_fiddy

For gasoline leaks, I use a product called Seal All. I've had it hold for years on the bottom of gas tanks, even carb floats. It's a bit thick for small areas, but since it contains MEK it might be thinnable with more MEK.