TOPIC:

Hi everyone, I just recently bought a '81 KZ440, it's my first bike. I've been having some erratic issues with it, but up until today it started and ran. I hope I put this in the right forum section...

When I bought it, it was missing the air cleaner cap (the part of the airbox that holds the filter), and the 2 boots to connect the carbs to the rest of the airbox. The carbs were open to the atmosphere, and with a little bit of fiddling with the choke it would fire up. Once the engine warmed up, I could shut the choke off and it would idle just fine. Unfortunately I can't speak for how well it performed out on the road, as I'm working towards getting my motorcycle licence. I can tell you that it putted around the parking lot just fine.

A few weeks later, after having some difficulty starting it, a new problem arose. The engine would not stay running without the choke in the on position, even when warm. I took the bike out for a little ride around the block, and once I rolled on the throttle and the rpms climbed to about 3k, they would continue to climb when I rolled off the throttle, I assume this is because of the choke being on.

Since then, I've been replacing parts here and there as I come across them, new battery, replacement tach+cable, and lucky for me I managed to find the very elusive air cleaner cap on eBay. So I installed the 2 dust boots to connect the carbs to the airbox (this required partial removal of the carbs), and installed the air cleaner cap, and was able to start it right after reinstalling the carbs. The same issue remained (unable to idle without choke [when the engine is warm]).

I got home from work today, tried to fire it up, and it won't start at all. Choke, no choke, petcock to prime, petcock to on, various throttle inputs, I don't know what to do from here on out. I tested the compression when I first bought it, 145 on both cylinders. Pulled the spark plugs today, and the tips were a little bit wet with gasoline, I'm unsure about the condition of the tips though. The owner just replaced them right before I bought the bike. I tested one plug and after a few tries of grounding it on the cylinder head (never tried this before, hopefully I did it right), I was able to see a spark.

Please help me, I'm determined to make this bike at least a semi-daily driver! I have some mechanical knowledge, a good ratchet set and some other basic tools as well as a service manual for the bike. Thanks in advance to anyone who takes the time to help, I'm stumped and don't personally know anyone that can help!

Cheers,

Jimmy

First, I'm no expert. I'd start by completely cleaning the carbs. If it's getting enough fuel and it's got compression, then it's probably a weak spark. Check the ignition coil/s.

All the answers to your questions are in your service manual.
Is it from Kawasaki,Clymers or Haynes?
Since you said you have spark start with cleaning the carbs.
Without the air box boots you probably sucked up some dirt and plugged up some passages in the carbs.
Hen go thru your ignition,valve adjustment and the rest of the regular maintenance.

Thanks for the replies. My manual is from Kawasaki, and I've definitely been using it. It's helped me on a lot of things already with the bike. Some ofItaly's for sure a little advanced for me, to say the least...

What you're saying makes a lot of sense, I didn't mention that I had a rough time squeezing the carb back into its position with the dust boots back in place. There was plenty of opportunity for a little crud to get in there. This was something I was unclear about when I was reading the shop manual, how can you install the carbs without having to fight the boots so much?

Buy new boots,the rubber gets old and hard,new are are soft.

Mine are pretty pliable but they're still a pain. I haven't found a great way to do it either.

You stated "...various throttle inputs..."

When starting any KZ engine DO NOT touch the throttle. For cold engine - key on, petcock on (or prime if vacuum type), kill switch in "RUN" position, choke on, battery fully charged, clutch lever pulled in, hit the starter button - bike should start. If it doesn't start make sure spark plugs are clean and dry and try again. Ed

Alright, so first off I'll apologize for posting and disappearing, I don't get too much time to work on the bike these days. I figured I'd just continue the topic instead of posting a new one.

I got it started! Now the problem I'm having is a 5k rpm idle, but more on that later.

First thing I did, was take the carbs off the bike, and without separating them, cleaned them as much as I could. I had a few clogged passageways, cleaned them out with a can of carb cleaner and a can of compressed air. There is one passageway on one carb that I couldn't clean, I'll show a picture of it. I tried spraying carb cleaner in the hole and letting it sit many times. I tried fishing line, but the brass hole is much too small.

This picture is a view of the right carb, from the top down, with the large metal cap and the vacuum diaphragm/slide removed. There are 2 brass openings pictured to the left of the slide bore, the one I cannot get clean is the one on top.



Is this passageway part of the idle system? Could it be contributing to my high idle?

I also checked the vacuum diaphragms and the slide, one of the diaphragms has a couple of patches on the rubber, but they are minimal and seem to be airtight. The slides move freely up and spring back down into place.

Anyways, I put the carbs back in (installing an inline fuel filter first), and to no avail, the bike still didn't start. Took the carbs out again to double check, and all the passages except that one are

I went through the ignition system and cleaned the electrical contacts, finding the leads on the ignition coil to be particularly crudded up. After cleaning those and replacing the plugs, she started up just fine, except now it wants to idle at 5k rpm.

I've checked the throttle cable, it's fine. I've checked the idle adjustment screw, and backed it off all the way, still nothing. I bought a propane torch and have tried testing for air leaks, but I can't find anything.

Here are the symptoms I'm having, as best as I can describe:

-Bike starts fine with choke OFF and NO throttle.
-Idle immediately climbs to ~5000 rpm and doesn't change after the engine is warm
-I can restrict the airflow entering the airbox by putting a towel over it, and bring the idle down to a manageable 1500 rpm
-I can also kill the engine by completely covering the airbox
-The exhaust is sooty and stinks when the idle gets below ~1250 rpm
-Turning the choke OFF causes the bike to pull in MORE air and the idle to want to climb MORE
-Throttle input RAISES the engine speed


Do these sound like symptoms of an air leak? Is it possible the previous owner re-jetted the carbs to work well without an air filter? I've tried contacting him but haven't gotten a response. The bike was very hard to start when I first got it (without part of the airbox), but ran very well once it warmed up.

So, I'm at a loss. Thinking of calling up the local bike shop, but I'm afraid that would cost me more money than it's worth. Sorry for the wall of text, I just wanted to be thorough in my description. Any suggestions are greatly appreciated!

Cheers,

Jimmy

I just pulled the carbs on my 440 LTD last night. Once I decided to unbolt the battery box and airbox, then slide them both back, the carbs pivoted out, easy as pie. The airbox being moved back that 1/2" or so means that the boots on that side are also pulled back and off of the carbs. A couple of plastic bags and rubber bands should keep things clean until I reinstall them.

Did you use the throttle stop screw (on the carbs) knob to adjust the idle? Ed

Killman, thanks for the tip, I never thought of removing the battery box. The extra space from unbolting the airbox definitely helps though.

Ed, yes that's the screw I used. Beneath the carbs in the centre. It's backed off enough that the throttle isn't touching it.

Pull carbs and completely clean them. And get some new carb boots. You will need an impact driver or needle nose visegrips to remove the screws.
The screw head on the bottom of your pic is your idle mixture screw.
Looks like it has not been touched.