Carburetor drips with petcock off

Carburetor drips with petcock off:
Where do I start to look?

1979 KZ1000 LTD

Your petcock is not stopping fuel flow like it should. And it sounds like you have a carb leak issue on top of that.

Regarding the petcock, there is no "off" (unless you have an aftermarket petcock.) The stock petcock shuts off fuel flow when a vacuum diaphragm closes with the engine off. One of the axioms of old bikes is that petcocks wear out, thus they leak.

I would start where Nessism suggests. It's a simple check to see if the petcock is leaking.

You probably have other issues as well. Where is the carb leaking?

Even with the petcock problem the carbs should not drip at all. The float inside each carb should shut off fuel flow before there is any drip because the float should shut off fuel flow before the fuel reaches the joint between the bowl and carb. It sounds like you have 2 different problems - one with the petcock and one with the carbs. When you find and fix the petcock problem you still need to find and fix the carb problem. Otherwise you may have fuel running into the cylinders when the engine is running at low rpm or shut off. Ed

hardrockminer wrote: I would start where Nessism suggests. It's a simple check to see if the petcock is leaking.

You probably have other issues as well. Where is the carb leaking?

I need to get a closer look to see exactly where the carb is dripping from.

Ed has also provided good advice. I was interested in knowing if your carbs are leaking at the Tee where the fuel line enters the carb.

I had the same problem (two problems). It drove me crazy. I cleaned the tank,rebuilt the petcock with new seals.Twice. Changed the float needles and seats.I couldnt get it sorted. In the end, I just fitted an on/off tap in the fuel line. It works fine so long as you remember to turn it off when you park the bike up.

The Ltd's have a manually operated petcock, i have had the very same problem this last week, clearly the carb valve is letting by, but your petcock is also letting by when off , they are non repairable, i purchased a pmc one not cheap and that let by exchanged for another pmc one and that was the same, so i bought a pingel from a local performance builder , twice the cost but it works, the PMC ones are having quality issues.

kevski wrote: The Ltd's have a manually operated petcock, i have had the very same problem this last week, clearly the carb valve is letting by, but your petcock is also letting by when off , they are non repairable, i purchased a pmc one not cheap and that let by exchanged for another pmc one and that was the same, so i bought a pingel from a local performance builder , twice the cost but it works, the PMC ones are having quality issues.

Just courious are you saying they are not repairable because you haven’t had success. The O-Rings are available and I have rebuilt one, It did leak some after but I think it was my fault I didn’t take my time and do a good job.

Mikaw wrote:

kevski wrote: The Ltd's have a manually operated petcock, i have had the very same problem this last week, clearly the carb valve is letting by, but your petcock is also letting by when off , they are non repairable, i purchased a pmc one not cheap and that let by exchanged for another pmc one and that was the same, so i bought a pingel from a local performance builder , twice the cost but it works, the PMC ones are having quality issues.

Just courious are you saying they are not repairable because you haven’t had success. The O-Rings are available and I have rebuilt one, It did leak some after but I think it was my fault I didn’t take my time and do a good job.

They are repairable but the core piece that directs fuel flow is impossible to find and no one makes it . I've only seen them once or twice in the last 10 years.

The core piece is what let's by, the rubber o rings are replaceable, but the carbs are overflowing which means the core is shot, yes I have tried to lap that part back in with metal polish to no avail, I tried 2 new PMC ones, they also let by, so purchased a pingel, job done, I have had a 12 dollar chinese one land today and low and behold completely identical to the 100 dollar PMC ones, I have not completely given up on my 42 year old one, I will make a brass sleeve to insert in the tap , also a brass cone and lap it in, just as an exercise in bloody mindedness.

I put the 12$ Chinese tap on a spare tank yesterday and filled it with petrol, went and looked this morning no letting by, you never can tell between a 100$ one and a 12$ one.