KZ440 - Sputters and stalls

I have an '82 KZ440a that starts to sputter after the engine warms up and then stalls. After it stalls, it is hard to restart. The bike has 2300 miles and has not been driven much. I just pulled it out a few weeks ago and started riding it again.

You can feel the hesitation, almost like a miss fire.

Can this be bad gas? - I poured a bottle of STP carb and fuel system cleaner in the tank and filled the tank, but did not drain the old gas before filling it. The tank is half full now.

Any suggestions are appreciated.

Lou

bullitt00692 wrote:

I have an '82 KZ440a that starts to sputter after the engine warms up and then stalls. After it stalls, it is hard to restart. The bike has 2300 miles and has not been driven much. I just pulled it out a few weeks ago and started riding it again.

You can feel the hesitation, almost like a miss fire.

Can this be bad gas? - I poured a bottle of STP carb and fuel system cleaner in the tank and filled the tank, but did not drain the old gas before filling it. The tank is half full now.

Any suggestions are appreciated.

Lou

How long was it stored with old gas? The carbs could be gummed up a bit. You could have some blocked passages. You didn't mention the choke - does it run with/without choke? Do you shut off the choke and then it stalls, or did you never use it at all?

Thanks for the reply.

Actually it runs with the choke wide open, but when I give it some throttle it dies. When I close the choke it idels and as soon as I give it some throttle, it dies.

Not sure about the age of the gas, but I think the gas was in the tank since last year - So perhaps 6 - 9 months old gas. The tank was half full when I started to ride the bike this season and I filled it up with regular.

The interesting fact is that the bike rode great for about 75 miles and then started to act up like this.

bullitt00692 wrote:

....The interesting fact is that the bike rode great for about 75 miles and then started to act up like this.

Okay, yeah that is interesting. That really makes me think that some gunk got dislodged or something. Or some rust from the tank. do you have in-line fuel filters? Well, either way, I'd take off the carbs and give them a bit of a cleaning.

Is there a way to clean the carbs while on the bike, perhaps with a spray cleaner or is it better to take them off and clean?

If I do take the carbs out, should I rebuild?

bullitt00692 wrote:

Is there a way to clean the carbs while on the bike, perhaps with a spray cleaner or is it better to take them off and clean?

If I do take the carbs out, should I rebuild?

I don't know about "rebuild" per se. You mean with new parts, right? I don't know. That depens on what you find..

I just mean take the carbs off, open the bowls, see if there's gunk, make sur ethe float valves are working correctly, use a little carb cleaner to get any gunk off in there, blow out passages with compressed air, etc. If you find a bunch of gunk, then you might be done after just the cleaning - if you find rusty bits, you might want to clean out the petcock and then your gas tank.... and get inline filters, which you should be using anyway...

Do a search for what other people did while cleaning thier carbs. Basically, you just have to keep the rubber parts protected from the carb cleaner, but the rest is pretty straight forward.

Also, make sure your air vent in the gas cap is allowing air to flow through. Many people don't know there's an air vent in the cap. If you want to test that, try running the bike with the cap open to see if it stays running....

Good luck!