TOPIC:

1978 KZ650B2, all stock, was running fine. Short story, I treated the tank with Kreem, and now it dies if I give it throttle.

Longer story: I treated the tank with Kreem, let it dry for 24 hours like it said, then put it back on, gassed up, and rode for a couple of hours. No issues. Morning 2 days later, it starts up and idles fine, but sputters and wants to die when I start out. If I rev it before putting it in gear and nurse it a little, I can get it moving and then there are no issues. If I stop and then start out again, it's OK, UNLESS I sit for a minute or two, like at a light, then I'll have to nurse it again. Warming up doesn't seem to help much.

Next morning (today) it's even worse -- I can't even rev it in neutral. Choke works fine, takes it up to 4K RPM as usual, but as soon as I give it any throttle, it dies. After a lot of warming up, I find I can blip the throttle and rev it, but if I try to hold it there it runs ragged then dies.

No vacuum leaks that I can find, all hoses connected properly, and in addition I synced the carbs while I had the tank off and all are close and in the recommended 18-24cm range. Tried running w/petcock on prime, no effect, and my inline fuel filter fills with fuel. I checked the drain screw in one of the bowls and it had fuel in it. Carbs were cleaned over the winter (not by me).

My question is, is it possible the Kreem didn't dry all the way, mixed into my fuel, and then clogged my pilot jets after sitting? If so, why weren't the idle circuits affected? Or could something else be gunked up? Or is the Kreem explanation unlikely and I should took elsewhere? What can I try short of taking the carbs off and dissassembling them?

Any help greatly appreciated.

ABR wrote:

1978 KZ650B2, all stock, was running fine. Short story, I treated the tank with Kreem, and now it dies if I give it throttle......

My question is, is it possible the Kreem didn't dry all the way, mixed into my fuel, and then clogged my pilot jets after sitting? If so, why weren't the idle circuits affected? Or could something else be gunked up? Or is the Kreem explanation unlikely and I should took elsewhere? What can I try short of taking the carbs off and dissassembling them?

Any help greatly appreciated.

Yep. Jettage.

Can't think of an alternative to opening 'em up and cleaning the needles, seats and jets that doesn't involve all the snake oil you can drink and the deed to some prime ocean-front real estate in New Jersey.

Sorry...

OK, thanks. Don't like to hear it but best to get it straight! Just to make sure I understand (I'm new to this stuff), the engine is dying too lean because opening the throttle lets more air in while fuel stays constant? I guess I don't fully understand why idling is unaffected -- is that a different circuit?

As far as solutions, is spraying carb cleaner into the fuel inlet a no-no? Like if I half-drained the float bowls, sprayed in mondo cleaner, then pumped the kickstarter a few times w/ignition off and throttle wide open to clear the jets?

you would have a very hard time for the cleaner to get threw the plugged jets doing it that way.The best way to do it is pull the carbs and pull the jets use carb cleaner and compressed air to blow threw the jets and passages.Plus some carb cleaner will eat up or disfigure rubber so be carful

What he said:

Carb Kleeners are indeed tough on rubber, so it's best not to torture an already abused carb even further.

Your mains are plugged, that's why it's gagging with any increase in throttle.

Spraying in gobs of cleaner is not likely to produce much in the way of results: they'd have to draw cleaner in order for the stuff to work, but if they're not drawing gas, how are they supposed to draw cleaner?

Best to bite the bullet, pull 'em, and manually clean the needles, seats pilot and main jets, check the float bowl heights and synch 'em with a manometer - half measures are likely to produce half results, and since you're in there, might as well do it right.

Best of luck with it...

How the heck did Kreem get through your fuel filter screen in your petcock, then your in line filter, then through the needles/seats, then into the carbs and clog jets??? I don't think so. Before you remove the carbs, I'd look at the petcock filter. If it's clean, no way in the world kreem got into the jets. Drain the gas and try fresh gas first.

Spraying in gobs of cleaner is not likely to produce much in the way of results: they'd have to draw cleaner in order for the stuff to work, but if they're not drawing gas, how are they supposed to draw cleaner?

Makes sense, but I thought maybe there was a little flow, enough to let it work in there and start dissolving. Anyway, I'm not in an easy position to pull the carbs (the bike is living on a Manhattan street) so I went ahead and tried it. The cleaner I used was OK on the rubber of the boots and gaskets, so I'll just have to hope my floats are OK.

And it worked -- after I drained the bowls and refilled, I started it up and was able to give it throttle. I went and got a new tank of gas, and the problem seems gone. A carb cleaning is probably in order, but it'll have to wait until I can get out to my cousin's garage where I can work on it properly.

How the heck did Kreem get through your fuel filter screen in your petcock, then your in line filter, then through the needles/seats, then into the carbs and clog jets???

My thought (maybe wrong) was the Kreem didn't dry fully, so went into a kind of solution with the gas, then after it dried out in the carbs overnight, something got stuck or clogged. Who knows? The station I bought the gas at was pretty sketchy, so that might have been it too.

Thanks for everyone's thoughts, I'll post how things come out with the carb cleaning (in a couple of weeks, probably).

ABR wrote:

And it worked -- after I drained the bowls and refilled, I started it up and was able to give it throttle. I went and got a new tank of gas, and the problem seems gone. A carb cleaning is probably in order, but it'll have to wait until I can get out to my cousin's garage where I can work on it properly.

Good news that it worked at least partially.

Probably a little difficult getting her wound out past 5 grand in Manhattan to find out - unless you want to go jogger-hunting in Central Park...

In any event, a good carb cleaning at your earliest opportunity is the best bet against a relapse...

Post edited by: Pterosaur, at: 2006/05/11 20:30