KZ440 - A can't seem to get running

Hello fellow KZ riders
This is my first post here and on any forum for that matter so bear with me here. So I recently picked up a 1980 KZ440 LTD for basically free of the ol' craigslist. I've been struggling to get it running for a while. I got it good about a month ago took it around the block. And nothing since. Originally it was reving real high and it wouldn't idle for for the life of it. So I pulled the carbs out and cleaned the for the 4th time this time I bought some micro bits to clean out the pilot jet back to the spec. I also put new gaskets on the carb manifold. Yesterday I threw it all back together and at last she idled down! Seemed to be running nice at 1.5 rpm. I was extremely relieved and after letting it run for a little to make sure it wasn't a fluke I took it out for a spin today . Right out of the driveway it hesitated for about 2 seconds then it perked up and took off as normal. That lasted about a quarter mile until it died. I couldn't get it started for the life of me. I got it started for 3 seconds then it seemed to backfire and die. Ended up walking the bike home. PLEASE HELP!!! I would love to get a few rides in before winter strikes at least. Hopefully I included enough information. Any questions ask away

Things I have done
Replaced for seals. New handle bars. New (used) exhaust. New battery. Cleaned the carbs multiple times and rebuilt. New manifold gasket. Set points gap and cleaned points. Cleaned the peacock. Set pilot screws. New spark plugs and gapped new fuses.

Hopefully i covered everything. Any help appreciated

Is the stock airbox & air filter installed? Airbox cap properly installed?

Yup stock air box filter. Replaced the foam screen on the air filter too

Sounds to me like you could have a fuel starvation problem where there's rust or debris in the gas tank and it's plugged up the filter in the fuel selector or the carburetors are compromised again.
Possibly something simple like a plug fuel line.
I would check all that before I went any further especially the rust and debri in the fuel tank getting junk into the needle and seats of the carburetors again.

I've replaced all the fuel lines vacuum lines and I cleaned the inside the tank and put a new inline fuel filter. It's possible it's been clogged from just a couple runs. The bike did sit for ten years after all
Do you think it could be a float level issue? That was gonna be my next check list item. Any other suggestions?

Verify that fuel flow from the petcock is good. A defective diaphragm can cause the bike to run really bad & you can't tell by looking at it whether or not the diaphragm is good. Or try riding the bike with the petcock set to PRI --- disconnect the petcock vac line & cap the ports.

What's the carb manifold gasket?

The rubber manifold going into the motor from the carbs. I've read of people putting a gasket there just to masked sure there's no vacuum leak. I'll try to post pictures soon. Is there a spot on this forum to post what type of bike I have and pictures. Still figuring this out

Make sure there aren't any vacuum leaks there. Typically, the carb holders are installed without gaskets or sealant.

So that each reply you make will list your bike: On the Profile page the bike model can be listed in the signature.
Profile page -->> right end of the long black bar -->> click the little [Edit >>] button. I guess it's the 1980 KZ440-A1 Ltd.

I like the possible bad coil when hot comment too ....

I don't have any idea how you cleaned the gas tank so it's hard to comment, but sometimes, and to be honest, that is where the extra crud comes from and you just loosened a lot of it up but didn't really get it all out. I have the Tee shirt.
Most of the time when there is crud down in the gas tank it will block the inline filter in pretty short time.... and if it gets past that into the fuel line>>> float needle and seat.... they usually hang up and the bowls will over flow, not run dry. It can happen the other way but not often.

However, crud can still block everything after that point and the carbs will just not flow any mixture into the cylinders.

missionkz wrote: I like the possible bad coil when hot comment too ....

Can you explain more?
Also I haven't synced the carbs tho they look pretty good eyeballing it. Would that be an issue? Also do you think the exhaust would be a culprit?

Good Fortune!

So I got her running... It was a simple fuel line fix. Dumb me. Went for a ride. Needs a little fine tuning. When I was riding the bike was kind of slowly pulsing like as if I was give and letting off the throttle slowly over n over again. I'm not sure how to explain it. It was like the rpms were waving up and down. Any suggestions? A vacuum problem?