Petcock Rebuild

[ecabo]

Here is some history of my bike saga. A friend gave me his bike last year when he was going back into cross country truck driving. I never did get it in rideable condition until very recently. Anyway, one of the problems I was having was the engine cutting off after only a few seconds of idling. Carburetor was cleaned and changed to new gas, but the problem pursists.

One day when I was checking out the gas tank for rust, I decided to check the fuel flow of the petcock. I put water in the tank, turned the petcock to the ON position and noticed the water was coming out in quick drops and not a steady stream. I had no idea that this was not normal because I have never seen how it is supposed to flow from the petcock.

This is what it looked like no matter what position the valve was set at. Notice in the picture that the valve is in the OFF position, but water is still dripping:


So I bought a new petcock from eBay:


The nut on the new petcock was too large and I could not swap it out with the nut from the old petcock. And here I thought it was a standard diameter. Silly me:


Since the two petcocks looked the same with the exception of the nut, I decided to open up the old petcock and swap out parts with the new petcock. In order to remove the valve, I had to drill out the rivets holding the valve in place. I was careful to drill out just enough so the valve plate can be lifted off. Here is what it looks like behind the valve:


I swapped the valve o-ring, diaphragm, spring and the o-ring on the collection bowl. The picture below shows the amount of deterioration in the valve o-ring and diaphragm. The diaphragm is supposed to have 3 open holes and one sealed hole:


In order to mount the valve plate back on the old petcock, I chose a couple of small diameter screws with course thread (they came from old computer parts) and cut to length. The petcock is made of soft metal so after drilling pilot holes I just forced the screws into place. Done and done:


The water flows out in a continuous stream now. Notice how I said water. That's because I'm still working on removing rust from the tank. I plan on working on that this weekend and a report will follow.

[SpudRider]

Nice job, Ecabo! Thank you for posting this excellent tutorial, and the superb photographs!

Spud

[ecabo]

Thanks Spud. I hope someone finds it useful.

Just in case some of us don't read all the forum categories, I'm looking for a couple of parts and hope someone can help. Here's the link to my wanted parts post: http://www.chinariders.net/modules.p...wtopic&t=12690

[2LZ]

Chinese rubber strikes again!

One of the Yamaha Enduro's I picked up when I was a kid had a rusty tank. Depending on how bad yours is, I took a sleeve of Daisy BB's and dumped them in and rattled that tank for a few days, then rinsed and rattled it again. Like shampoo...'rinse, repeat'. Worked amazingly well.
Steer completely clear of Kreem.