TOPIC:

you should click the link in wg's sig, he has a great site, very informative

SO!!!! Ok, I just went for a nice short little ride after a couple days of horrible riding weather and when I pulled back into my garage I left the motor running and got off to check things out. It IS leaking fuel from where the exhaust leaves the head.#2 is ESPECIALLY bad. So fuel ISN'T being burned in the carb and is being expelled out into the exhaust and/or crankcase....
So now what do I do?

Dump the oil and check it out... I had so much gas in mine, it filled the case past the oil window. When I dumped the oil it was full of gas.. very bad for your motor and milage. Ended up beaing bad needle and seats, plus my pet cock was leaking.



2bskor wrote:

I have a 79 kz1000st and it also gets real bad mileage.
I am now wondering if it is going in my crankcase as my sight glass is frothy almost like there is water in the oil. I changed the oil and the filter even took the cover off and cleaned the window:S

Sorry to hijack you problem but if the fuel is going into my crankcase would it burn off or how would I tell and how is it getting there.

My tank takes roughly 15 litres or 4 gallons and I'm lucky to get 100 kms or 45 miles.

the carb bowls drip a bit but never that much and there is no other visible fuel leak.

The only way for fuel to get into the motor is through the carbs. Needle and seats, float level, petcock. I'm not sure how it would leak from the exhuast though. It could be in your crankcase but I don't know how raw fuel can just come out of the exhaust. The only way for it to get into the exhaust is through the exhaust valve, which would mean you are burning it. Your plugs would be black, you might even have black smoke coming from the exhaust from unburned fuel.

Bicycle Lee wrote:

SO!!!! Ok, I just went for a nice short little ride after a couple days of horrible riding weather and when I pulled back into my garage I left the motor running and got off to check things out. It IS leaking fuel from where the exhaust leaves the head.#2 is ESPECIALLY bad. So fuel ISN'T being burned in the carb and is being expelled out into the exhaust and/or crankcase....
So now what do I do?

I meant right where the pipes come out of the head....not the actual exhaust itself...on the front of the motor where the pipes come out, that flange was dripping fuel....

You mean the exhaust side of the motor? Gas must be leaking and running down the cooling fins to the front of the bike? There is no wqy fuel can get to the front of the bike. It has to be dripping onto the cylinder block from the tank or carbs... I dunno, sounds very strange to me BL...

hey, that just makes TWO impossible things this bike is doing!
I am just saying what it LOOKS like my bike is doing....where the exhaust comes out of the head is dripping gas...and I am 99.99999999998% sure that it isn't the tank that is leaking.

If I was you BL, I wouldn't ride that bike until you find the leak. If what you say is true, that gas is leaking onto your hot header.... BL go BOOOOM!!! Seriously.... Find the leak. Pull the tank off of the bike you might have a pinhole or something underneath it. If it's not the tank, how about the fuel line? Look at the carbs, if gas is leaking out of the carbs, I would say the #1 or #4 carb and running to the front of the motor off of the cooling fins. Gas only comes from one place, the tank... Follow the gas trail and find out where it's coming from. Follow the drip backwards.. Don't ride it until you do though, you could blow yourself up man!

If the cylinder is not firing then it's pumping gas out the exhaust, and then it leaks out the exhaust port and drips.

Not all that unusual, and the fix is normally new float needle valves.

My brother's 82 KZ1000M did that last year, I installed new float needle valves (and I insisted he buy new carb air boots or I wouldn't fix it) and it ran great again.

Take the spark plug out of #2 and you will probably see that it's wet with gas.

Post edited by: steell, at: 2007/05/06 20:46

Thanks. Steell....I've got a whole day off to devote to this tomorrow...I just hope I can find some float needle valves at a moment's notice.

How is your bike running? If your bike was missing a cylinder or two, i think you would notice... Your saying the bike gets bad gas milage, not that it's running like it's missing a cylinder.. The bike would run like super crap..

Link14 wrote:

Do you have a vacuum petcock. I was getting pretty lousy gas mileage for a kz400 (~20 mpg) and when I talked to my mechanic and told him that along with my carboned up plug, he checked and found my diaphram cracked.

Not sure if it fixed the problem, still haven't gotten the bike back yet.

I think Link14 is talking about the diaphram in the petcock itself. If that gets cracked or gets a tiny pinhole it can allow gas to leak through it and suck gas straight to the cylinder it is hooked to. Pull the hose off the petcock and see if it is wet inside. If it is, there is your problem.