Fuel in the crank

I have a 1982 KZ 750 and the fuel keeps filling up the crank case. I have been told that the petcock valve is faulty but I thought that the carbs would shut of the gas supply when they where filled, (float shut off). Does anyone have any input please?

Do you have vacuum petcock? Its possible that it has a bad diaphram in it. One way to check is to unhook you're fuel line and make sure the petcock is either turned to ON or Reserve but NOT Prime. There should be no fuel coming out. If there is you'll have to replace the diaphram.

Have you tried giving the carbs some taps on the fuel bowls with a screwdriver handle. Sometimes that helps the needle seat in the orifice.

Perhaps WG or some of the other guys can jump in here.

Later, Doug

If the petcock actually is leaking, with the bike on the side stand the floats in the carb don't always close the needle and fuel will leak into the carb. I figure that is why Kawasaki in their wisdom put the vaccum petcocks on the bikes to begin with. Just my opinion of course.
Ride safe

Post edited by: The Milkman, at: 2007/06/22 12:03

You are correct, this is a vacuum petcock. I will repair or replace it first.Is it possible to replace this with a simple on-off valve? Thanks for the response.

Invicta 39 wrote:

You are correct, this is a vacuum petcock. I will repair or replace it first.Is it possible to replace this with a simple on-off valve? Thanks for the response.

Yes, but you will need to get an adapter plate to switch from the bolt-on vacuum kind to the screw-on manual type. You can get these from here: www.z1enterprises.com/SearchResult.aspx?...ds=petcock%20adapter

The way we found out the vacuum petcock diaphrams were bad is when we pulled the vacuum line off the carb, fuel dripped out.

Before you replace with an on-off petcock (or spend way too much for a replacement diaphram :pinch: ) you might want to check this thread:

kzrider.com/component/option,com_joomlab...,3/id,148539/#148539

Wish I'd seen it before I'd fixed my petcock.

Good luck

Link14 wrote:

Before you replace with an on-off petcock (or spend way too much for a replacement diaphram :pinch: ) you might want to check this thread:

kzrider.com/component/option,com_joomlab...,3/id,148539/#148539

Yes, one thing to consider about buying a new diaphram (other than the high cost :pinch: ) is that they don't always fix the problem. You could shell out $50 for a new diaphram and find that it still leaks.

That's why I chose to get a new Suzuki vacuum petcock (as described in the link above). It was cheaper than a new diaphram and works prefectly.

Thanks for the help. I think the problem will be solved with the repair kit from Z1. Again, any thanks.

Yeah, the diaphram cost me $60 but so far it's working:P

measure bolt to bolt on the petcock and just buy a replacement..

part # KL18-4358 44mm fits great on my 650.. From www.z1enterprises.com/catalog.aspx?pid=KZ650-B3-1979