Vacuum Petcock

I am having serious trouble with petcock on 79 KZ650C (Custom). I replaced diaphragm. Now once bike is running for 5-6 miles, the gas get choked off. I am not sure if parts ordered were correct because of uncertain if the correct petcock is on this bike. Has anyone switched to gravity feed? If so what preparations are needed? Is it a straight switch?
I tried to order a new one, but they are a discontinued item. Getting desperate.

A lot of guys have switched to Pingel petcocks. www.pingelonline.com is their website. Yes, you have to turn off the gas when stopped but the petcock is a well machined item and should last many years.

I can offer two options. First a newer version of this petcock is available from Kawasaki.Part # 51023-1375 is a Vacuum Operated petcock which will replace your old unit.You will also be able to get replacement parts for it. Or you can purchase Kawasaki Part # 51023-057. This is an original style ON , Off, & Reserve. It is a manually operated petcock. You will have to block off the vacuum port on the caburetors with a cap if you go with this style. I purchased both of these units from Z-Power UK. They have a great selection of KZ650 new parts and aftermarket parts as well. Good luck

Vacuum petcocks are a pain !
The Vacuum is only used to let the gas flow when the engine is running.
All (99%) our petcocks are gravity feed.
Pingle makes a replacement, which needs an adapter.
www.pingelonline.com/powerflo_application_frames.htm

Also I'll add that Z1 has inexpensive manual operated
petcocks that work fine, so long as you remember to turn them on and off. You need an adapter plate with it, but all together you won't spend more than 30-40 dollars. Pingel petcocks (top of the line) cost more $80-(90 plus adapter.

With a manual petcock you will need to put a cap on the vacuum port on the carb; size 7/32" rubber cap.

Hope this helps
JIM

Before giving up on the existing petcock, if not already done, would check the following ---

Assure vacuum line from carb to petcock is in good shape, not cracked or split or leaking or kinked, and is firmly attached at both the carb nipple and the petcock nipple. The vacuum petcock won't properly function without the correct vacuum being supplied to it from the carb.

Assure fuel tank is properly venting. Test run with cap ajar (not fully snapped down) to see whether problem continues. The issue might possibly be an obstructed vent in the fuel tank cap casuing fuel starvation (bike "runs out of gas"). Petcock can't flow if no gas is getting into it from the fuel tank.

Remove petcock from tank and clean the screens on the fuel pick-up tubes, which if clogged, won't allow gas into the petcock.

If fuel tank has grit or crud inside, it may require flushing out to prevent the suspended matter from hovering about and collecting on the petcock pick-up tubes while the engine is running. And not allowing gas into the petcock.

Also check in-line fuel filter to assure it's still allowing sufficient fuel to pass through and on into the carb.

Good Luck!

I got rid of mine and put in a manual fuel tap.

1980 LTD KZ650E1. I wanted to keep the vacuum petcock. I got my replacement yesterday from Z1 Enterprises, #KL18-4359, $47 total, including shipping (44 mil hole spacing, which is very close to 1 3/4").
The thing bolted right on, no mods necessary. Works great!
I am running pods, so I have no airbox, don't know if that would've got in the way or not.
When I got mine, I tested it; I blew thru the outlet while applying vacuum with my vacuum 'gun'. It took so little vacuum, that it barely registered on the gage, when it 'flowed'. It has a reserve position also; I wondered if that was always on, but upon testing, found that was also controlled by vacuum - which is great, because if I run on reserve, then forget to switch the petcock back, I don't have to worry about gas continuing to be delivered to my carbs.
1 pic of old/original petcock, 1 pic of the new one installed.
Highly recommended
Hope I helped someone.

Here is the other pic(new one installed):

Wild and KZ Guy wrote:

I blew thru the outlet while applying vacuum with my vacuum 'gun'.

One handy tool to have! :blink:

Congrats on your fuel flow!! :laugh: GLuck!

Cool!
But I bet my old girlfriend could create more suction :whistle:

If that is the case, why is she your old girlfriend?

Wild and KZ Guy wrote:

Cool!
But I bet my old girlfriend could create more suction :whistle:

Refresh my memory....
Is her number still 867-5309?



Jenny Jenny!