TOPIC:

I'm rebuilding a set of CV34 Keihin's and struggling with leaking overflow tubes in the float bowls. Three of the four bowls had cracked tubes so I soldered the cracks closed only one of them seems to also be leaking where the tube enters the float bowl. These particular float bowls seemed to have had the nipple on the bottom of the float bowls plugged, or maybe they were never drilled in the first place. So in effect the overflow tubes never worked anyway. I (stupidly) drilled out the nipple to make the overflow functional however.

My 1981 carbs didn't even have the tubes at all (see photo) so it seems that a running change was made at some point.

I'm now wondering what the best course of action is: plug the tubes, get some gas tank sealer and paint the tubes, or try to replace the tubes. I'm leaning towards cutting off the tubes but then I'll have to plug the holes in some way.

Open to suggestions

Later Cv34s did not have overflow tubes. In case fuel overflows... it goes into the airbox not the engine. Airbox has a hose drain for this case.

Question now is how to fix?

Could maybe plug hole with small screw. I've found some small and tiny ones in old circuit boards which worked in handle bar switch gear. Might fit carb where brass tube goes.

Yeah, a small screw is a possibility, after tapping the hole. Any idea what kind of sealer to use on the threads?

Has anyone ever tried to remove one of those tubes before? Seems to me it must pull out or I could drill it out. Then simply press a new piece of tubing in it's place. Guess I better see if I can source the tubing before getting ahead of myself here...

EDIT: Found a nifty tutorial on replacing the tube. Nothing to lose...cx500forum.com/forum/general-discussion/...ube-raplacement.html

Used that CX500 guide and got er done! Piece of cake. Replaced all three tubes that were cracked.

Hardest part was rolling over the edge of the new tubing to shrink the hole size, and getting the old tube out.
To roll the hole closed on the tube the little dimple on the side of a threading die was used.

This is a simple and robust fix. Way better than soldering.

P1030567 by nessism , on Flickr

Great job on replacing the overflow tube. I have had those leak at the base where it attaches to the bowl. I sealed the leak with JB Weld (not JB Quick) with long term satisfactory results. I've also soldered them with good results. Your repair is more elegant and I'm sure a longer term fix.

Thank you!

Today's project was making a new fuel Tee...

P1030580 by nessism , on Flickr

Sweet. Care to share how you made it?

Cut the main body with the grooves using a mini lathe and a slug of brass. Then drilled the cross hole on a drill press. The barb piece came from a fitting purchased at the hardware store. I cut off the end then turned it down for a good fit into the main body. Last part was to silver braze the two pieces together. It took me a little longer than I care to admit, but the next time it will be faster since I know what to do now.