Kawasaki VN750 Forum banner

1 - 20 of 23 Posts

·
Registered
Joined
·
2,687 Posts
Discussion Starter #1
I can't get my petcock to stop leaking, I've done about everything I can think of, including putting in a rebuild kit and stretching out the spring in it to see if it would help in closing the valve.

So I'd like to buy one that's in good shape. Pretty tired of dealing with this with no results at all. Anyone got one for sale?
 

·
romeobravo172
Joined
·
842 Posts
When you say it is leaking, is that externally or is fuel coming out to the carbs without vacume?
 

·
Registered
Joined
·
2,687 Posts
Discussion Starter #3
Fuel coming out of the proper outputs but without vacuum applied to it.
 

·
Banned
Joined
·
10,354 Posts
Have you opened it up and cleaned out the insides ? Theres a tiny rubber diaphragm in there...if it gets a decent size speck of dirt, or dries out, that could cause seepage...
And there's another thread here someplace about using a Yamaha petcock, not vaccuum acctuated....its just one outlet, so you'd need a brass "tee" to split the lines...
 

·
Registered
Joined
·
2,687 Posts
Discussion Starter #5
Yea, I opened it up, cleaned it up real well and put the whole rebuild kit in it, stretched the spring a little bit to make up for wear and the valve still remains open :-/
 

·
Banned
Joined
·
10,354 Posts
...odd, since you rebuilt it...hmmmm...now....yers is an 85 like mine...you DO know that if you have it set to prime, it WILL run all the time, yes ?...keep it on on or res....if its still leaking and it wasnt on prime, then the unit itself must be shot...

In theory, with the older petcocks with the prime setting, you can remove the vaccuum line completely and plug, use the on/res for the OFF and the prime for the ON...
 

·
Registered
Joined
·
2,687 Posts
Discussion Starter #7
lol yea I know, I tried it in both res and on, and they both leak... "pri" gives me a full flow.
 

·
Banned
Joined
·
10,354 Posts
Okay, so its not an actual leak, but a trickle....sounds like that lil vaccuum diaphragm then....try this...blow INTO the vac line going into the petcock....see if that stops it....if it doesnt, then the diaphragm is bad....OR the diaphragm seat...

In a pinch, until you fix it, plug both ends of that vaccuum actuator line...the one on the petcock will fill with gas, and you can run the bike on prime then....but it really sounds like its a diaphragm problem...best option IMO is to go with a non-vac replacement....I'll be doing that myself soon...too much frickin safety crep on these bikes nowadays...
 

·
Registered
Joined
·
2,687 Posts
Discussion Starter #9
I put in a new diaphragm, since it came in the rebuild kit. I think the real issue might be the spring that keeps it shut, cause the o-rings and the diaphragm are new.
 

·
romeobravo172
Joined
·
842 Posts
Got to ask a stupid ?, did you put the spring on the correct side of the diaphram. Would be easy to put it on the nipple side!
 

·
Registered
Joined
·
1,021 Posts
Check this older thread, same issue.

http://www.vn750.com/forum/showthread.php?t=18442#post174633

Check diagram to ensure all is as should be. Also, having not seen the inside of one of these, does the diaphram have to go in a certain direction (i.e if reversed would cause this issue) or can it be put back in either direction?
 

·
romeobravo172
Joined
·
842 Posts
To work properly the diaphram needs to be installed correctly, can it go in say backwards from the diagram that might be possible. The nipple part with the small o-ring faces the selector. The spring is on the back plate side of the diaphram. If the spring is around the nipple that would make if flow all the time. Now the diaphram can be installed incorectly with the nipple and spring in the proper positioning but turned to where the line up tit does not mate. The PC will work properly but will leak externally once vacume is applied. Wolfie suggested blowing into the pet-cock (pull hose at carb), I,m not sure that will do anything, I say that just from my own experience that there is a ck valve inside the brass fitting where the vacume tube from carb fits. Neg pressure (vacume) it allows diaphram to pull back, positive pressure it shuts off the path so diaphram does not move, supposedly the spring allready has the fuel shut off. I think that is another safety feature rarely seen. exp, what might happen to that diaphram if you got a back-fire thru the left carb, could prob blow that tissue thin diaphram to pieces.
 

·
Registered
Joined
·
2,687 Posts
Discussion Starter #13
Yea, the first time I put the petcock back on the tank and saw fuel coming out I took it apart and made sure the spring was placed correctly and everything was lined up properly. After a few other tries, fuel still comes out without vacuum applied.
 

·
romeobravo172
Joined
·
842 Posts
Damn Bro, I'm at a loss here---Thinkin,Thinkin---------
 

·
Registered
Joined
·
2,687 Posts
Discussion Starter #15
Me too... I even tried combinations between my old diaphragm, the new one, the old o-ring on the tip of it and the new one, just to see if one of the combinations would keep it shut since the o-rings looked a tiny bit different to me... it was barely noticeable by me and I may have just been making it up in my mind after so much looking into it lol. Anyway, nothing I tried worked and the only thing I haven't been able to replace is the spring... I think. Gonna look and see if I don't have an old one around somewhere.
 

·
Registered
Joined
·
2,687 Posts
Discussion Starter #16
Still need one, if anyone has a petcock in decent shape. Can't seem to find many options on eBay lately.
 

·
Banned
Joined
·
10,354 Posts
There was a thread somewhere talking about aftermarket petcocks...no diaphragms...pure mechanical...someone on the board was using one...forgot who, and forgot the vendor...too sick right now to search, sorry....
 

·
..have a vulcan good day!
Joined
·
4,508 Posts
...too sick right now to search, sorry....
Reply With Quote
...too much Hot Tub / Partyin' ? :)

:smiley_th
 
1 - 20 of 23 Posts
Top