Leaking Carburetor...Solved

[vincejames]

I wanted to just share how I was able to solve the issues I was having that was causing gas to leak out of my carburetor when my petcocks were turned to on. I say petcocks because my 1978 XS650 w/ BS38s had two vacuum type petcocks. One on each side of the tank.

I have come to the conclusion that there are three different reasons why your carburetor would be leaking gas.

1. Float level. It is important that your float level is set exactly at spec. You check these levels buy placing two clear tubes in the 10mm drain holes on the float bowl. I have found that holding your carbs in vise and keeping them level is the best way to do this. Once you have your clean tubes hooked up, pump has through the carbs and see what the level is. Photo below.

2. Float needles and seats. These are the first thing I would replace. I've had terrible experiences with Mike XSs', so get them off of boats.net. There is a link on the forums somewhere.

3. Hairline cracks on brass fittings in float bowl. This is a rare one that not many people know about. It is important to check all brass fittings in the float bowl and the carbs themselves and make sure there are not any cracks.

Float Level

Check for cracks in any brass fittings/jets

 

[TwoManyXS1Bs]

3. Hairline cracks on copper fittings in float bowl. This is a rare one that not many people know about. It is important to check all copper fittings in the float bowl and the carbs themselves and make sure there are not any cracks...

Yes, this is a good one. With all that vibration and exposure to stale gas, brass ages and hardens, becomes brittle. So, add ALL thin brass to that list, including floats, overflow tubes, petcock tubes,...etc.

Here's a pic of a split overflow tube:

71XS1B Carbs Overflow03 It gets worse. Not only were bubbles emerging from the base of the overflow tubes, but from vertical splits as well.

• TwoManyXS1Bs
• Oct 25, 2015

 

[vincejames]

Great photo!!!