Leaking Petcock

I removed my petcock from my '82 XJ750, cleaned it and installed new gaskets.
Prime works just fine, fuel flows out of it.
Res leaks
On leaks

It's not just a small leak, it's a steady flow out of the petcock. It's not as much flow as the Prime position, maybe half the flow rate. I didn't replace the selector lever o-ring, which was bad (Len didn't have a replacement in stock, and didn't get to a store to replace it yet). Could that lead to that much flow coming out of the petcock, or could it be the diaphram? I didn't touch the diaphram side of the petcock, as everything seemed to be fine.

Here is a picture of the seat, and the o-ring was fine.

 

I can't see the seat well enough to see if there's any pitting. I would polish the seat, and when installing the diaphragm, use a new spring and possibly even a spacer washer.

It's important when installing the diaphragms and plate that you kind of "orbit" the parts around a bit so that everything sits down nice. If the design of the petcock permits, I'll take a (wetted) Q-Tip and gently operate the diaphragm against the spring a few times and let it reseat before fully tightening the diaphragm plate screws.

 

Here is a cropped shot of the Petcock. I cleaned it and polished it after this, before installing it back on the gas tank.



I think at this point, instead of throwing more money into the petcock to 'rebuild' it, I'd rather just get a whole one. I believe I saw somewhere that there is an On-Off valve that is a direct replacement for the petcock.

 

The seat area looks like it isn't flat and smooth, it's got concentric grooves in it. It needs to be flat and smooth. I touched mine up with a 60 degree centering drill (a 60 degree countersink will work too) in a drill press after clamping the petcock body square. A new diaphragm spring or shimming washer will be a must. Polishing it most likely did not remove the grooves. Could you post an "after" picture?

 

I concur. That seat isn't going to seal in that condition, even "polished," those grooves have to come out.

Since that's NOT the "correct" original petcock for your bike, replacement either way might be a viable option.