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Reason for editing: Last Edit: March 22, 2013, 16:54:40 PM by John Hopkins

As nobody has answered yet I will give it a go..

I have stripped and repaired several petcocks like this and they are all pretty simple..

Now it is possible that the 800 is very different to the 1500 but the 1500 is not a vacuum fuel tap..if the 800 is a vacuum fuel tap or petcock then instead of just having the one outlet hose it should have another hose at the back of the petcock which sucks air from the tap to the carb, this provides the vacuum, if that hose has slipped off you will not have a vacuum and the fuel will not flow...

So based on this I am going to go with the same petcock as the 1500 before FI.

First take a photo of the petcock attached to the tank and the hose..

Photo's before during and after doing any work pemove the probability of incorrect re-assembly..

now consider this statement as a first step..

I noticed my fuel petcock is allowing fuel to leak through it, while in the "on" or "reserve" positions.  (no actual "fuel leak" i.e. dripping on the ground, just leaking through to the carb).

Now look at the diagram and consider this..

The petcock has three positions...

ON..air or gas (petrol) can pass through the long tube to the outlet at the bottom of the petcock and into the fuel pipe but not through the short tube..

RESERVE..air or gas can pass through the short tube to the outlet but not through the long tube.

OFF..no air or gas can pass throught either tube to the outlet..

You can test the switch in each position by blowing through the long and short tubes and putting your finger over/ close to the outlet..

From this description you can see that fuel should still feed to the carb even with the engine switched off and you should switch off the petcock when parking the bike..

As a foot note, having re-read your post the centre of the diaphragm (if fitted) has a tubular section that the spring sits in, if that is damaged or deformed the fluid may leak past that section which should serve to block off the inlet from both the long and short inlets, if the spring is condensed this could prevent the tubular part from sealing..

A closer look at the centre section of the diaphragm while gently stretching it may reveal a split or pin hole and gently stretching the spring if the diaphragm is good may cure your problem.

I hope this helps.

John.

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Topic summary

Posted by greenbarn

- March 20, 2013, 18:14:34 PM

Well one thing leads to another.... When I took my tank off to do some other projects, I noticed my fuel petcock is allowing fuel to leak through it, while in the "on" or "reserve" positions. (no actual "fuel leak" i.e. dripping on the ground, just leaking through to the carb).

My understanding is that in the on/reserve positions, the petcock should basically function as a shut off valve, and only open when the running engine supplies vacuum to the diaphragm on the back of the valve. There is a drawing (random google pic) attached as a reference, for a valve of basically similar design. The way I understand this gizmo is that the O-ring (670) closes off the fuel, which is pushed in place by the spring (92081) on the outside of the diaphragm. When vacuum is applied to the diaphragm, it pulls the stop out, letting fuel go by the o-ring.

I dis-assembled my valve, and honestly can't see anything wrong with it. Ther is no visible hole in the diaphagm, and the o-ring seems to be intact. The way I see it, the only thing that could allow the leak when not running is the o-ring and spring?? SO, even though they look fine, I guess I need to buy some parts.

Has anybody out there had to do this repair? What parts did you use? The only posts I saw in the history referenced buying an entire new valve.

Choices:

1) Amazon has an aftermarket kit (made by K&L I believe), and other retailers (J&P cycles etcl) but I saw a couple of negative reviews. You never know if this is from bad product or operator error.

2) Dealer can get individual parts, but I wasn't clear talking to the parts counter guy that I was getting everything I need. I could have him fax me his diagram to verify.

3) aftermarket OEM non-dealer parts supplier: there are several OEM on-line suppliers. However, they all seem to use the same diagram and I don't see any part numbers for the diaphragm itself.

Has anybody used the K&L kit??

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