kz1000 misfiring under load

I've got an '82 kz1000ltd with about 10k miles on it. I've rebuilt the carbs, added a fuel filter, set the valves and sync'd the carbs. I ride the bike around town and it runs great. Maybe a little cold-blooded but once warmed-up it runs great.

I rode it on a trip a few weeks back, going about 200 miles. After about 60 miles the bike began running like it was starving for fuel. I pulled up the choke lever and no change. I switched to prime and no change. I pulled into a gas station and filled up as it was time for gas anyway.. I rode at slower speeds and it seemed ok.

I continued on my trip and it ran well most of the time, and occasionally would run badly as I explained above. I would rev it up and try and keep the revs up and it was sputtering and finally would run well.

I'm stumped - the plugs looked fairly normal, just a little darker than normal which I though could be from the choke.

I was thinking of putting on new ingnition wires and new caps but figured I would consult the voice of experience at KZ Rider!

Thanks in advance for your help.

kink in the fuel line ?

If you have multimeter you should be able to test the plug caps and ignition wire ? I have found that a little dab of dielectric grease on the metal top of the plug where it fits into the cap is a good thing.

I checked them and they were at 5K ohms. One is missing the rubber gasket around the part where the wire goes into the plug cap.

I have replacement wire for the coils but not the caps. I need to order a set...

How's the fuel line ? I've had the same happen to me when I used to use the clear plastic tubing and it would harden up and kink restricting fuel flow and come on like starvation.

I have the large black fuel line with a NAPA 3006 fuel filter. It has a straight tip on one end and a 90-degree end on the other - great for 4-cylinder bikes. They are about $4. It does not seem to be lacking fuel.

I drained the carb bowls also and no water came out. I will ride it to work this week and see what happens.

Any chance you might be getting a vapor lock from a plugged vent hole on your gas cap?

Take off the gas cap and take a look under your cap and see if you have a diaphragm and vent holes. These have been known to get condensation and fine rust debris built up over the years.

I drilled mine out a tiny bit larger and it solved my problem that sounded similar to what you are experiencing. Its worth a shot and only take a couple of minutes to do.

Cheers-Colin Firth-Ontario Canada

Mine has an aftermarket cap.... I will check it out!!!