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Discussion Starter · #1 ·
I have this 350 that has never leaked from carbs or petcock. The petcock has always been tough to turn but worked well. the other day I noticed that the petcock turned much more easily than normal. This is odd because I ride every day. I noticed immediately.

I ride around that day and notice a tiny amount of leakage. You could call it "seeping." I noticed the threaded part of the tank is wet so I think the fuel is leaking "up" out of the chrome two sided nut.

I go ahead and drain the tank and rebuild the petcock. Parts inside were new. I bent the faceplate a little to return some resistance to the lever. However it is not as firm as before. I crank the chrome nut down TIGHT. It's O ring is intact.

Put everything back together, same problem persists.
 

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Discussion Starter · #3 ·
I'm pretty sure the internals are Honda parts as I'm pretty sure this was a new Honda petcock installed recently. The guy I bought it from said it had an aftermarket petcock when he got it.

I have used many 4into1 kits and installed many petcocks and never had any trouble with leakage like this.
 

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I'm pretty sure the internals are Honda parts as I'm pretty sure this was a new Honda petcock installed recently. The guy I bought it from said it had an aftermarket petcock when he got it.

I have used many 4into1 kits and installed many petcocks and never had any trouble with leakage like this.
I got news for you. OEM Honda parts aren't exactly up to par where ethanol is concerned.
I've had NOS OEM o rings and gaskets failed miserably in carbs before so....
 

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Discussion Starter · #5 ·
Interesting to consider. I don't know if it's NOS or new new. I will have to take it back apart and look at it again I guess, when the tank gets lower.
 

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Discussion Starter · #6 ·
I thought I had it fixed but I think it was just less pressure on the fitting because the tank was low. I filled up yesterday and this morning it had seeped more than I'd seen before. It was enough to be everywhere!

Is there a possible hardware store replacement of the O ring in the chrome nut? Or do I need to order from 4into1 and wait?
 

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I wouldn't use a hardware store o-ring, likely to be a plumbing part designed for water.

An auto supply store should be able to match the size with an o-ring made for use in fuel systems.
 

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Discussion Starter · #8 ·
If I remember correctly the o-ring has a square or pentagon section profile, not round. May be possible but i'm not hopeful! I think I'll just order a kit.
 

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Discussion Starter · #9 ·
The leaking persists. Still waiting on petcock parts from 4into1. But I am starting to think that's not the problem. It may be the tank itself leaking, or both. Not sure yet. I stops when I get down to the reserve level. I tried only putting 1 gallon in so I could still lride while I wait, but it's leaking like crazy.

I also noticed that it seems like the cap burped a little on the top of the tank. Is is possible that the tank is not venting properly and thus forcing fuel out of other orifices?
 

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There's a trick to getting the connection to the tank to not leak. The nut needs to be only halfway threaded onto the petcock before you put it on the tank bung and start tightening. That way, it draws both parts together equally before running out of threads on either end, with the gasket tight in the center.

As for the lever moving too easily (and possibly leaking), usually just tightening up the screws that attach the front plate to the petcock will solve that. If it doesn't, then the rubber part inside the petcock may be worn out.
 

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Discussion Starter · #11 ·
I finally received petcock parts after a delay. I put it all together very meticulously and filled with gas. Unfortunately it was still leaking as before. Tank was off the bike so I was able to look underneath and conclude that the there was a pinhole leak in the tank.

The tank had been lined before with POR15 so I ordered some of that, and applied it two nights ago. I applied it normally on the inside of the tank like the instructions say, and i dabbed a bit on the outside (underside) of the tank. It's where one of the "wrinkles" are from manufacturing. Hopefully this fixes the problem!
 

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Discussion Starter · #12 ·
I filled the tank with gas last night which was the end of the 96 hour cure time. For now the leak is fixed.
 
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