84 KZ440 running rough. help!

I'm not sure if this is electrical, or carb problems, so I'll drop this question in Engine....

My old KZ440 that I sold almost three years ago has been sitting in a barn for two years... the new owners left gas in the tank, carbs and disassembled a bunch of stuff. When they couldn't get it started (two years later) I was asked for their money back.. Out of good faith I've offered to help get the bike in shape again so it can be put back on the road. After a new petcock and a thorough cleaning of the carbs (overnighted in gunk) the carbs were clean and good to go. checked all the electrical, and the coil and ignotion module are all in spec too. Here's the problem. When I try and fire it up, it idles perfectly. Crack the throttle a bit, and it revs nicely. open the throttle up, it chockes, sputters, and will die if you leave it there. I pull my plugs and one shows running super rich, the other is tan... swap plugs and the 'good' plug now shows carboning up. wires have no resistance... I'm stumped. I'd almost swear it was carbs, but they were thoroughly cleaned and I'm not sure it explains the plug..... also, timing is bang on...

and it struggles for 7k rpm... maybe it is a carb problem?

Thanks in advance for all those who help me help another out!!!

and mods, you can move this into whichever subforum you feel is best..


James

Do you have the air filter connected to the carbs? My limited experience with the 440 is that it is very "touchy" when the filter assy is disconnected from the carbs.

Just my .02 worth...

air filter is connected as well..

i have an 83' 440,...does the same thing....it has been sitting for 10 years,...i cleaned the carbs, it ran better....but its the same story as yours.....i am going to put it in the shop and get the carbs done professionally,....i think mine is a carb problem from sitting so long good luck, and i'll be interested to see what the progress is....

If you want to be thorough in trouble shooting this... I think you have two coils? If so, swap the coils with their wire and see if the problem moves. If it doesn't and you are using a factory airbox, then the internal passageways inside the carburetors are in need of cleaning. If the shop you use doesn't disassemble and clean the carburetor bodies ultrasonically, I suspect that the problem won't go away. Many shops spray off the carbs with carb cleaner and install rebuild kits. There really isn't a rebuild kit for the 440... the one sold has a bowl gasket, float needle and mixture screw. The only other thing that can make one carb rich while the other is OK is the needle jet which should be examined closely for ovaling. The needle jets on the little 440 Keihin carbs are cast out of aluminum and don't hold up great. The needle jet is the orifice that sticks out of the bottom of the venturi. To have a good look, you pretty much need to pull out the slide diaphragms and look down into the venturi. The jet needle can also be worn... it is easier to see and check by just pushing the slide up. Oh yeah, I guess you need to ensure that both slides rise and fall at the same time and the diaphragms are seated properly. The diaphragms on the 440 are fussy to seat.

wiredgeorge wrote:

If you want to be thorough in trouble shooting this... I think you have two coils? If so, swap the coils with their wire and see if the problem moves. If it doesn't and you are using a factory airbox, then the internal passageways inside the carburetors are in need of cleaning. If the shop you use doesn't disassemble and clean the carburetor bodies ultrasonically, I suspect that the problem won't go away. Many shops spray off the carbs with carb cleaner and install rebuild kits. There really isn't a rebuild kit for the 440... the one sold has a bowl gasket, float needle and mixture screw. The only other thing that can make one carb rich while the other is OK is the needle jet which should be examined closely for ovaling. The needle jets on the little 440 Keihin carbs are cast out of aluminum and don't hold up great. The needle jet is the orifice that sticks out of the bottom of the venturi. To have a good look, you pretty much need to pull out the slide diaphragms and look down into the venturi. The jet needle can also be worn... it is easier to see and check by just pushing the slide up. Oh yeah, I guess you need to ensure that both slides rise and fall at the same time and the diaphragms are seated properly. The diaphragms on the 440 are fussy to seat.

I've only got one coil, so I cannot easily switch the coil. I cleaned the carbs myself ( and I don't have an ultrasonic cleaner, but I had gunk and an air compressor to clean... the needle jets looked good as well (mine are brass and had no marks from where they seat). I could check and see if I seated the diaphragm correctly on the left cylinder... perhaps my problem lies there?

Thanks and I'll let you guys/gals know whats going on in a few hours! :S

The one coil has two inputs two outputs switch the outputs first.

Single coil... hmmm both cylinders fire at once? If that is the case, then by all means swap the ignition wires and see if the problem moves.