KZ 650 wont run

Hello everyone,

I have just joined this site and have only had a bike for about 2 months, when i purchased a 78 kz650 from a friend of mine. It has approx. 30,000 miles and I cleaned it up pretty nice but recently I ran into some problems.

It has always required starting fluid to turn over. It has pods installed recently. It has run excellent at idle but when you open it up all the way, it bogs down. However the other day I filled it up with 93 octane gas (the gas station I have come to find out has been almost notorious for having water in their gas) and got on the road and it didnt have the acceleration or top speed it did previously. Thinking that I have needed to clean the carbs I went ahead and took them off and cleaned them pretty good. Now I put the carbs back on and the bike still needs starter fluid to start.... but it will only stay started for 2 minutes or so and wont run in first gear at all...

I have put seafoam in and hoped that would try and clean up any gas...but I am thinking that maybe the carbs need adjustment? Petcock? fuel lines?

Please help.....

Thanks for your time
Brian Clarke
kz650
Charleston, SC

Well..... after further frustration.... the bike will only start for a second and then die.... however if you continue to spray starter fluid into it (which it did in spurts of every 5 seconds for a total of 15 seconds) then it will continue to run.... which tells me that its not getting enough gas?
1) Maybe I have the hoses out of the petcock mixed up (hose coming out of the left branches off into carb 2-3, hose coming straight down goes to a nipple in carb 2)
2) The air mix screws in the carb (the little screws on the outside of each carb facing away are tight as before)
3) The gas is bad?
4) All screws inside the bowl are screwed tight ( dont know if i need to back em a couple turns or what)

well first off welcome to the kzr jungle:) Seecond off these old kz's dont need anything higher than 87, unless the has been motor work done, and compression is 10:1 or higher. The pod's could also be why you ran into problems, probally the bike is probally running lean due to alot more air because of the pods. So re jetting is probally in order. If you still have the stock airbox, try putting it back on, to see if the problem goes away. In the mean time drain all that 93 octane from the tank and carbs. And put in some non watered down 87, and se what happens. Check your spark plugs to.

Welcome to KZr Brian.

As already mentioned, if the carbs weren't re-jetted after installing the pod filters it WILL be running lean.
Not a good idea to run it like that, as it can possibly do some serious engine damage. :pinch:

When you reinstalled the carbs after cleaning them, are you sure you reconnected all of the vacuum hoses properly and still have the rubber caps covering the 4 brass fittings on the intake manifolds (rubber boots between carbs and engine)?

If you're bike still has the original petcock, there should be two hoses running from it.
The larger hose is your fuel feed, and should run from the larger fitting on the petcock to the "T" fitting in between carbs #2 and #3.
The smaller hose is your vacuum feed, and should run from the smaller fitting on the petcock to a fitting on the left front side of carb #2.
If that smaller hose is disconnected, pinched or cracked/damaged in any way, it will prevent your carbs from getting any fuel with the petcock in either the "RUN/ON" or "RES" (reserve) positions.
Try this.
Run a hose from the bottom fitting of the #1 carb float bowl into a container and loosen the float bowl drain screw (about 2~3 turns is usually enough). Then switch the petcock lever to the "PRI" (prime) position, this will allow the fuel to flow via gravity rather than vacuum.
If fuel flows out, then it just might be that you have a vacuum issue. Check the remaining carbs in the same way to make sure that they all flow fuel decently.

There is also a brass fitting on the left rear of carbs #2 and #4, these are the float bowl vents.
There should be hoses connected to them that normally would route up and over the airbox to vent the float bowls.
If these are capped off, or the hoses are pinched closed/clogged, the bowls will become pressurized and prevent fuel from entering the carbs to fill them.

I'd recommend disconnecting (or better yet replacing if they're the originals) all of the fuel and vacuum hoses one by one, then blowing air through them to make sure there's nothing clogging or preventing them from working like they should.

One more thing.
Have you tried starting and running it with the fuel capp open?
It might not be venting properly, and could be vapor-locking and causing your bike to not want to start.

The fact that you need to using starting fluid to get the bike running means something is wrong with your bike. More than likely the carbs are clogged with old gas and dirt. I remember reading somewhere that using too much starter fluid can damage the engine. Take your carbs apart and clean them. Also make sure your petcock and gas tank are clean. The pods will cause your engine to run lean, you will need to rejet your carbs. Do a search on this forum for the recommended jet sizes.
Wiredgeorge has a website and forum that is an excellent source for carb information. The site
is at www.wgcarbs.com you will find a link to the forum. You can buy jets from z1enterprises.com or other suppliers. I am not that familier with the connections/screw locations on your carbs but a service manual will contain all this information so you can get the carbs hooked up and adjusted correctly. Once you get the carbs cleaned up you may want to check your ignition system. When was the last time you did a tune up?? I would look at plugs,wires,points..etc to make sure everything is working correctly. Sometimes poor running may not be a fuel problem but an ignition issue. Not saying that this is the case with your bike but it is something to keep in mind.

sounds to me like your pilots or your choke pick up is plugged. pilot jets are about 3 bucks each at the dealer, i could not find VM22 pilots at Z1, but then again i did not call, went to the dealer because of no shipping.
i would take apart your carbs again, and while you have the tank off, measure voltage at your coils and look at the coils themselves
RRRR the 650's just have a drain plug, they don't pipe into the overflow like other bikes do. i guess you could check full flow buy pulling the plug on the #1 carb and see if it keeps running.

brianpclarke wrote:

Well..... after further frustration.... the bike will only start for a second and then die..

2) The air mix screws in the carb (the little screws on the outside of each carb facing away are tight as before)

I hope you did not turn the air screws in tight as hell. They should be set about 1-1/2 to 2 turns out. If you mashed them in there then try to remove them and see if the tips are busted off. If any tip is broken off then that carb is now junk. If they all look good then lightly seat them and turn them out 1-1/2 to start with.

WOW! Thanks for all of the feedback guys.... unfortunately it got dark pretty quick and there is nothing worse than mechanical work in the dark...but it doesnt seem to be a vacuum issue cause i set the petcock to prime and checked all the bowls.... i guess i am going to try and get someone to do an untrasonic cleaning on the carbs and rejet them...but i will get back here within the end of the week to tell everyone how it is going.

Also, anyone live near Charleston SC?

Thanks again,
Brian Clarke
1978 kz650

Your bike is junk...give it to me!:ohmy:

Just kidding...welcome!...you've been given some great advice. Good luck and post pics as soon as you get a chance!...then give me your bike!:laugh:

i run 93 octane and 87 and think my bike runs better on 93??? of course my bike doesnt run exactly right anyway