bad idle....backfire

Bike sat in storage for about 6 years. Did all the usual things like oil change and such. ran great when I parked it.

It will start easily with the choke full on. I let idle a few minutes to warm up. Then I start to back off the choke and she starts to die. I can't even keep her alive with throttle. Once she is warm I can give her throttle with the choke partially on but she backfires.

I took the carbs off and took the bowls off and cleaned the main jets. I took them out and they seemed clogged. I sprayed with carb cleaner and they opened up. Put everything back together and I get the same thing. Plugs seem to be firing OK.

Did I miss an idle jet somewhere? HELP!

79' KZ 650

Sounds lean? Mine had similar trouble, after a new ignition it ran alot better.
Could be vacuum leak (intake boots are dry-rotted)
Thus causing a "lean" state.
Rebuild the carbs, and replace the intake boots.
Also, check out the points/timing.
While your at it, go for the dyna ignition upgrade......its worth it!!

Post edited by: fallenknight308, at: 2006/07/14 05:13

The carbs need to be removed, totally disassembled and thoroughly cleaned and rebuilt and then tuned. The rubber bits associated with the carbs should all be thrown out and replaced... intake manifolds, vacuum caps and hoses.

So we are talking about a total rebuild then? The boots were a little cracked but when it was running I sprayed some starting fluid on them and nothing changed. I will replace them anyway.

Does anyone know where I can get a diagram for the carbs. I want to know what the hell I am doing so I can put them together properly. Will adequate instructions come with a rebuild kit? Also, where can I get an inexpensive but decent rebuild kit?

Thanks,
Paul

For diagrams go here www.kawasaki.com/product_home.asp
Click on Owner Info, Click on Parts Diagrams. Select Motorcycle etc etc

Rebuild kits are not generally expensive. Check with www.z1enterprises.com/default.aspx
They dont come with instructions but the diagrams from above will help and you can find tons of info here.

Good luck

I just went through thexact same roblem with my bike. check your mixtur screws and ake wg's advice- TOTALLY disassemble the carbs and soak all the functional parts

I looked on the z1 site. Nothing for my bike. KZ650 goes up to 78.

Anyone know of another source? I really hate to take this thing to a shop.

try here

www.z1enterprises.com/catalog.aspx?pid=KZ650

HI, This is exactly what my bike was doing except after a while I was able to get it to run without choke but it was backfiring a lot out the exhaust. Very impressive loud backfires to say the least. I didn't see a rebuild kit for my 1980 KZ650 either. I dug into my carbs first and then found there isn't much in there to fail. There is a rubber O ring on the bottom of each carb where it connects to the bowl. There are two diaphrams that are part of the accelerator on the bowl of carb 2. I just replaced these, the bowl gasket, the carb top gasket and the air box hoses and now it is running great. As for all the jets and things I just made sure there wasn't any gunk in them. Eyeballed all the holes to see if there was any obstructions and pushed a small wire or screwdriver down into places I couldn't see. It wasn't nearly as hard as I thought it would be. My biggest problem afterward was that I also put on new fuel line and I had too much so it kinked after a short while and ran the carbs out of gas.

HI, This is exactly what my bike was doing except after a while I was able to get it to run without choke but it was backfiring a lot out the exhaust. Very impressive loud backfires to say the least. I didn't see a rebuild kit for my 1980 KZ650 either. I dug into my carbs first and then found there isn't much in there to fail. There is a rubber O ring on the bottom of each carb where it connects to the bowl. There are two diaphrams that are part of the accelerator on the bowl of carb 2. I just replaced these, the bowl gasket, the carb top gasket and the air box hoses and now it is running great. As for all the jets and things I just made sure there wasn't any gunk in them. Eyeballed all the holes to see if there was any obstructions and pushed a small wire or screwdriver down into places I couldn't see. It wasn't nearly as hard as I thought it would be. My biggest problem afterward was that I also put on new fuel line and I had too much so it kinked after a short while and ran the carbs out of gas.