Replacement petcock - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 10 Old 07-28-2017, 06:12 AM Thread Starter
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Replacement petcock

1988 KLR650 A2

I've got quite a serious fuel leak on my 1988 KLR650 A2.

I've stripped the carburettor and set the float level as per the official KLR service manual for the CVK 40 carb.

I suspect the petcock because after the bike was stored for a while the petcock was in a bit of a state. I used a petcock repair kit that included a new diaphragm and O rings etc.
However the leak is still present.
To remove the built up crud inside the petcock it was quickly dipped in 35% Hydrochloric acid then washed with water.
What I think has happened is that the acid not only removed the crud but a few microns of metal from the petcock body so that the rubber seals are not holding the fuel.

Biting on the bullet I've decided to buy a new petcock, however my petcock has two tube outlets, one that goes to float chamber and the other that I believe is a vacuum pipe that operates the diaphragm.

Most of the new petcocks that state they are for my 1988 model have only one outlet point and nothing for operating a vacuum diaphragm. I can only find used petcocks that have both outlets which I don't really want to buy.

Can these simple "On/OFF" be used, and if yes what about the vacuum tube that comes from the top half of the CVK40, can this be simply blanked off?

Many thanks for any help or advice.

James.
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post #2 of 10 Old 07-28-2017, 07:47 PM
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If your float valve inside your carburetor float bowl works, you should have no leaks, regardless of your petcock condition.

If you have a leak, recommend you inspect the float valve point and its seat. Point should be smooth and pliable (not hard); seat should be clean and smooth.

Commend to you the thread, "Carb Overhaul," on this website.

Anyhow, yes, you can use a manual-activation only petcock, and yes, if you do, block off the carburetor vacuum port.
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Last edited by Damocles; 07-28-2017 at 07:49 PM.
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post #3 of 10 Old 07-30-2017, 05:44 PM
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We might be of more help if we knew where the leak is coming from. Not just the drip point, but where the gas is actually getting out. Does it leak with the petcock set to "OFF" of just when it is "ON"?
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post #4 of 10 Old 07-31-2017, 03:28 PM Thread Starter
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Quote:
Originally Posted by GoMotor View Post
We might be of more help if we knew where the leak is coming from. Not just the drip point, but where the gas is actually getting out. Does it leak with the petcock set to "OFF" of just when it is "ON"?
It does leak with the petcock set to "Off" which does suggest that a replacement petcock is needed.


Damocles, I did strip and check the carburetor and followed the instructions from the KLR 650 manual as to how to set the the float level. I did this with the carb lightly held level in a vice and a plastic tube from the overflow nipple connected to the body of a calibrated syringe to get the level exact.
It was only when I re-installed the carb to the bike when the leak is apparent.
The leak does appear to be coming from the overflow nipple at the base of the carb.

I've ordered a new petcock that will fit the tank that also has the vacuum facility.
There was this one (EDIT: forum does not allow me to post the eBay link) but I ordered this identical unit (EDIT: forum does not allow me to post the eBay link)

I'll give an update when it arrives and is fitted.

Thanks to all for the very useful information,
James.
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post #5 of 10 Old 07-31-2017, 05:22 PM
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Since you have ordered an new petcock it doesn't matter much, but the petcock can be rebuilt by replacing the worn internal parts. 1988 Kawasaki KLR650 (KL650-A2) Fuel Tank | CyclePartsNation Kawasaki Parts Nation

Sometimes gas residue can build up around the O-ring #670 just as in the carburetor. This keeps spring #92081 from seating the O-ring properly and allows fuel to leak into the fuel line to the carburetor.

Sometimes the rubber gasket #11009 can leak fuel out the front around the on-off-reserve lever.

A damaged diaphragm #43028 can also be replaced.

This is why I was asking exactly where the fuel was leaking from.
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post #6 of 10 Old 07-31-2017, 05:24 PM
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Even if a manually-activated only petcock is in the ON position, the float valve should seal the float bowl and no fuel should exit the overflow.

When the float bowl fills with fuel, the float rises, and the float valve closes . . . that's the preferred scenario, anyway. With a functioning float valve, the carburetor should not leak, even with an open petcock.

I think this matter is discussed in, "Care and Feeding of the CVK," Googleable and listed on another thread on this website.
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post #7 of 10 Old 08-01-2017, 03:44 AM Thread Starter
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Quote:
Originally Posted by Damocles View Post
Even if a manually-activated only petcock is in the ON position, the float valve should seal the float bowl and no fuel should exit the overflow.

When the float bowl fills with fuel, the float rises, and the float valve closes . . . that's the preferred scenario, anyway. With a functioning float valve, the carburetor should not leak, even with an open petcock.

I think this matter is discussed in, "Care and Feeding of the CVK," Googleable and listed on another thread on this website.
Thanks again for the advice, I'll take the carb off again and double check the float valve as you've described above.
I did read also the step by step strip down and service of the CVK40

GoMotor I mentioned in my original post that I fitted a petcock repair kit that included a new diaphragm and that I think the petcock body was compromised after it was immersed in hydrochloric acid which I think made the diameter that the "O" ring is supposed to seal too big, thus letting fuel past.
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post #8 of 10 Old 08-01-2017, 11:39 AM
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With functional drain screw and float valve, don't see how carb can leak; leastwise, not as a function of a leaky petcock.

KLR250 has a similar, but smaller, CVK carburetor, and . . . a manually-activated only petcock. Shouldn't but . . . I DO leave the petcock ON after I kill the engine . . . carburetor hasn't leaked yet. (I know; I know--KLR250 owners, do NOT try this at home! )
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post #9 of 10 Old 08-01-2017, 03:19 PM Thread Starter
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Problem solved (Hopefully)

Since re-reading the replies from Damocles and GoMotor, I decided to remove the carburetor and strip it down again.

I followed the excellent YouTube videos by souperdoo and did all of the suggested maintenance.

When it came to the re-build section of the video I checked the float height that should be 17.5 mm. However when I checked this measurement mine was more than 22m. !!!!

So you were exactly right when the float system was suspected. With the float height too high fuel would be spilling down the overflow tube.

I've now bent the tang so that the float height is now exactly 17.5mm.

I'm going to re-fit the carb tomorrow and hope that it will now not overflow.

I think that I may have mentioned that the bike had stood for quite a few years without use, this resulted in that the fuel tank was quite rusty. I used a powerful rust cleaning agent as well as loads of old nuts and bolts in it and shaking it around lots to de-rust the tank.

I still think that fine rust particles may reach the carburetor which was evident today when stripping down the carb, so before the new filtered petcock arrives, I'm going to fit the largest in-line fuel filter possible.

Once again thank you both for your spot on advice without which I would still be struggling in the dark.

James.
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post #10 of 10 Old 08-01-2017, 05:50 PM
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You can test the carburetor for leaks before installing it by just turning the fuel line up and filling the line with gas.
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