Rebuilding the Yamaha Vacuum Fuel Valve w/pics

Even rebuilt, they do need to be periodically cleaned; remember it's upstream from any inline fuel filter and subject to catching crud big time.

Don't assume failure; it's amazing how many things can be fixed with a good disassemble and clean.

 

Strewth bigfitz that's some beautiful work.

 

You're the best

 

I couldn't agree more. This is one of "the" best documented DIY tips that's on this site. You do some nice work my friend!

 

it's amazing how he does it. IT looks like it's brand NEW!!!!!! like it came straight out of the factory. Free from wear and defects.

 

Hey Fitz, on that second seat that was too pitted to polish out... I had a similar issue with a 650 petcock. I used a 60 degree counter sink to "kiss" the face of the bevel and after 0.004", it was pretty as new. I need to get the rebuild kit in so I can report on how well this worked so more news later. I'm ordering the delux OEM rebuild kit with the aftermarket spring to compensate for the removed material. What say you?

 

I saw that in your other post, and thought "brave SOB anyway."

I'd be worried about removing too much material. As long as the "head" of the diaphragm assembly is still long enough to reach in there and seat the o-ring properly, without bottoming out on the spacer plate, it should work. I'd definitely use the longer aftermarket spring; you may or may not need the "booster" washer as well.

Sounds like you used a "machinist's touch" and are probably ok.

I've got one right now that has a couple of stubborn wear rings in it; I'm just going to step up to valve lapping compound and give it a quick whirl, then re-polish.

 

Very nicely done Bigfitz

Here's some more useful stuff for others considering the rebuild


http://www.maxim-x.com/petcock.html

 

Lots of good stuff in that article; unfortunately he's dead wrong on a couple of key points; I'm not going to pick it apart but if you carefully polish the valve seat so that it's shiny new smooth (under a magnifying glass) the rebuild kits work fine if you use their slightly longer/stronger spring.

The key is the valve seat; but a good careful polishing will do the trick.

 

Any reason i couldn't bead blast this instead of cleaning it by hand?

 

Depending on the pressure and coarseness of the beads you use, you run the risk of pitting the metal, especially in that o-ring seat area. The metal used in these petcocks is kind of "soft" and if you put gouges in any of the sealing surfaces, the petcock body is toast.

 

I'll go a bit stronger than that: NOOO!!!! Bead blasting will simply ruin all the parts.

Soda blasting only; and don't concentrate the blast on the valve seat area for any length of time.

The metal in these petcocks is soft enough you can scratch it by biting it. Honest. Kinda like gold...

 

This thread is the stuff legends are made of

Love your work.. Especially Len and Fitz in this case

 

K, just bought a cheap gun and have loved what it's done so far for parts of the GS450.... Curious as to what else I can do... My motorcycle trailer's next

 

This is what I been looking for, thanks

 

where can I buy the on/off replacement value?

 

where can I buy the on/off replacement value?

 

XJ4Ever; click the logo in the site banner or PM member chacal.

 

Back on the road thanks to your tips!

 

Finally got my petcock rebuilt. Thanks Fitz.

I didn't purchase a new filter pipe because mine was in great shape. I did notice what appeared to be some sort of epoxy residue when I removed it and had to pick it out and clean around the flange where it was seated. I'm wondering if I should apply a bit of epoxy around the base of the filer to insure a good seal before I put it back on? It fits relatively snug in the petcock body but I doubt it is fluid tight.