FA vs The Petcock - Round 1 - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 11 (permalink) Old 05-11-2010, 08:10 AM Thread Starter
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FA vs The Petcock - Round 1

Well, round 1 went to the petcock. The backstory to this is that I had been smelling a slight odor of gasoline for a month or so, normally in the mornings when I went out to the garage to start the bike up. A couple of weeks ago, I stopped for gas on the way home, filled her up, and then rode to the house. I parked in the garage and went inside, only to be given an instruction to go and pick something up at the store by SWMBO. I went back out to the bike and noticed gas dripping from the petcock. After a few choice words, I caged it over to the store and back.

The next morning, I went out to the bike and there was no gas dripping. I started the bike up and immediately noticed gas dripping from the petcock again. I killed the engine and the dripping ceased. I drained the gas out of the tank and pulled the petcock off. I disassembled the rear section, revealing the diaphragm and noted that the little rubber(ish) pieces on each side were fraying and worn. Having believed that I had correctly diagnosed the problem, I ordered a new diaphragm and waited a week for the stealership to get it in.

Having received my new diaphragm, I installed it, put the petcock back together, and reinstalled it in the tank. I remounted the tank and started filling it with gas. At that point, the petcock began to laugh riotously (I swear! I heard it!) and started spewing gas onto the floor of my garage. Round 1 - The Petcock.

I now realize that, having taken the petcock off of the tank, I probably need to replace that oblong rubber o-ring that goes between the petcock and the tank (it has been ordered). I also likely need to replace the nylon washers for the bolts that bolt the petcock to the tank. I've already reefed down on the four screws on the back of the petcock that secure the diaphragm, so I should be good there. I didn't disassemble the front part of the diaphragm, so in theory, that should be good.

Any other suggestions?

--FA

K.J. "Fire Ant" Lord
VROC #28807
Decatur, TX
'03 VN750 "Serenity"

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post #2 of 11 (permalink) Old 05-11-2010, 08:45 AM
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i used copper washers instead of the nylon i figured they would last longer make sure you clean the tank really well also other than that there isnt a lot left.


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post #3 of 11 (permalink) Old 05-11-2010, 10:08 AM
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I just rebuilt the petcock and it's leaking out the back side. Now I get to pull everyting and see if I can figure why it's leaking! Score two for the petcocks!

I'm keepin' all the left over parts. I'm gonna use 'em to build another bike!
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post #4 of 11 (permalink) Old 05-11-2010, 07:20 PM Thread Starter
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Petcocks - 2, Humans - 0. This is not good.... LOL.

--FA

K.J. "Fire Ant" Lord
VROC #28807
Decatur, TX
'03 VN750 "Serenity"

Rear Turn Signal Relocation
Front Brake Replacement
Spline lube, per Fergy's excellent instructions (that he has posted around here somewhere)
Kevlar Clutch Plates
Metzeler ME880 Tires
Stebel Nautilus Air Horn
ACCTs Rebuilt
Saddlemen Explorer Seat
MCCTs Installed
Kuryakyn Wide Levers Installed
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post #5 of 11 (permalink) Old 05-11-2010, 08:28 PM
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The Vulcan 750 petcock is a poor design to begin with. I dislike vacuum petcocks. The one on my '93 never leaked, but I did have to rebuild the one on my '02. I replaced the vacuum diaphragm parts and the oblong rubber o-ring. It has been close to 2 years, and it has not leaked anymore so far. If it ever does, I will probably fix it like I did the one on my dirtbike. Remove everything in it, seal it up good, plug the vacuum fitting on the petcock and the carb, and just use it as a fitting, with no way to turn it off. On my dirtbike, if I need to shut the fuel off, I just pull the rubber line off what used to be the petcock, and replace it with another short piece of rubber line with a screw in one end, which caps it off. I would much rather do that once in a while than deal with a constantly leaking petcock. Jerry.

I am a motorcyclist, NOT a biker.


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post #6 of 11 (permalink) Old 05-12-2010, 12:34 PM
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Quote:
Originally Posted by Fire Ant View Post
Petcocks - 2, Humans - 0. This is not good.... LOL.

--FA
Cantankerous little bastards aren't they? The PO of my bike complained about it too. He did what your gonna do FA and I haven't had a problem with it for going on 3 years now. Sounds like a winner...
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post #7 of 11 (permalink) Old 05-12-2010, 06:25 PM Thread Starter
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Quote:
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Cantankerous little bastards aren't they? The PO of my bike complained about it too. He did what your gonna do FA and I haven't had a problem with it for going on 3 years now. Sounds like a winner...
Good to know. I'll be sure to let everyone know how it goes. I'm expecting that O-ring to come in tomorrow...

--FA

K.J. "Fire Ant" Lord
VROC #28807
Decatur, TX
'03 VN750 "Serenity"

Rear Turn Signal Relocation
Front Brake Replacement
Spline lube, per Fergy's excellent instructions (that he has posted around here somewhere)
Kevlar Clutch Plates
Metzeler ME880 Tires
Stebel Nautilus Air Horn
ACCTs Rebuilt
Saddlemen Explorer Seat
MCCTs Installed
Kuryakyn Wide Levers Installed
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post #8 of 11 (permalink) Old 05-12-2010, 08:15 PM
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I also had a leaking petcock and I got the full rebuild kit and it still leaked. I ended up going to the junkyard and got one that was alright and put the new kit on that one and haven't had any problems. I believe the leak was comming from one of the arms that the fuel lines plug on to.
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post #9 of 11 (permalink) Old 05-17-2010, 08:03 AM Thread Starter
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Round 2 goes to FA

Well, this weekend I replaced the O-ring that sits between the petcock and the underside of the tank. I first took a stiff-bristled nylon brush to the underside of the tank to get loose some of the less obstinate crud, then used a sharp chisel to very carefully scrape off any remnants of the previous o-ring that could have buggered up the seal. I then took the brush to the whole area again, and to the top of the petcock, and bolted it back on. I used new nylon washers on the bolts. I also made sure to reef down on the four screws holding the diaphragm in.

Once it was all put back together, I fired it up. Actually, it didn't "fire up". It complained about being awakened from its two-week slumber, and a judicious amount of cranking was required. Then I remembered that since I had only put about a gallon of gas in the tank to test out the seal, I needed to switch the valve to Reserve.

Eventually, it started up and we took a ride. 30 or so miles later, no leaks. I plan on suiting up and heading to work here in a few minutes. I'm going to ride for a couple of days before I declare this one a knockout....

--FA

K.J. "Fire Ant" Lord
VROC #28807
Decatur, TX
'03 VN750 "Serenity"

Rear Turn Signal Relocation
Front Brake Replacement
Spline lube, per Fergy's excellent instructions (that he has posted around here somewhere)
Kevlar Clutch Plates
Metzeler ME880 Tires
Stebel Nautilus Air Horn
ACCTs Rebuilt
Saddlemen Explorer Seat
MCCTs Installed
Kuryakyn Wide Levers Installed
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post #10 of 11 (permalink) Old 06-05-2010, 07:17 PM
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Do we need to have a vacuum petcock? Can we just use a shut off valve instead?
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