Is it a carb issue? I think so, but man I dunno!

Hey fellow KZ riders, I'm brand new to the land of KZ's and motorcycles in general. Just picked up an 82 KZ440d belt drive from some guy on craigslist a few weeks ago. Went ahead and got my motorcycle license, and have been enjoying the hell out of riding it around. HOWEVER, things aren't great. It's never been a great rider, has always started very harshly. I need to put it on full choke to get it started, and it needs to warm up for a good full 3 minutes before taking the choke off. When starting it always kicks out a bunch of whitish smoke too, which seems to go away after running for about 5 minutes.

So when it's still relatively cold it idles ok at about 1,000rpm's, but pops a lot. After warming up riding it for 15-20 minutes, the idle shoots all the way up to approx. 4000rpm's! I've been told this could be a leaking carb issue, or an airflow issue. I found that I have the correct airbox and filter, and as far as I can tell there is no leak from the box to the intake boots, but not so sure about the carb boots. I've sprayed cleaner all over but can't seem to find a leak. And perhaps the weirdest thing of all? Everytime I switch the bike off after riding for awhile, it backfires about 2 seconds after turning it off!

Then to make matters more complicated, yesterday when I was riding it it started running really badly, and just up and died. It wouldn't start, so I waited ten minutes, put the choke fully on and basically had to rev it all the way back home so it wouldn't die!

As you can probably tell I don't really know my mechanics too much, but am excited to learn. Anybody familiar with these symptoms? I have one idea too, sometimes a little gas leaks from the bottom of the float bowl, could this have gotten into the oil? I don't have any sort of overflow tubing running from the nipples, is there supposed to be?

Alright KZgeniuses, thanks for any insight you may have.

Welcome to the madness. :silly:

with a 28 year old CL bike it is best to assume that no maintenance has been done since it was new.It is quite possible that there is more than one problem, so a careful, systematic approach is needed. A factory shop manual (fsm) is invaluable for this. Get one.

It sounds like you have probably eliminated the usual air leaks as the problem, though the air injector system (pollution control), the carb diaphragms and throttle shafts can also introduce unwanted air.

Have you checked the valve clearances?
Cam chain?
Ignition system?
These need to be up to snuff for good running and carb diagnosis.
Fuel level, carb cleanliness and carb adjustment are also necessary.
In other words, a thorough tune up is likely in order. That may sound intimidating, but it is not really that tough, it just takes knowledge (fsm and this forum), some basic tools, and some patience. It's a good way to get better acquainted with your ride and with the crazies around here. :laugh:


P.S. Most of the folks around here are picture addicts and we expect you to feed our problem.

Sounds like bike needs a good tune-up.Also sounds like bike is running way too lean (backfiring).This could be result of timing being off or the dreaded airus leakus disease,which u have apparently looked for with the spray technique.I am sure some 440 gurus will have some other issues for u to look at as well.good luck.bj

I would check the easy things first. Remove and inspect the air filter and verify the air filter element is a lightly oiled and clean sponge type. Then I would open up the cap on the right side of the engine, above the oil level indicator window, and clean / lube the timing advancer. Make sure that the arms connected to the springs move with finger force.

If gas is leaking out of the float bowl drain nipple, try unscrewing the drain screw to drain the carb bowl and inspect the gas for debris. Then lightly reseat the drain screw. If you do not find the main culprit and there are no other air leaks, a carb cleaning / rebuild is likely in order. Like said earlier, get a Field Service Manual (available for free online) to help out with step by steps for your particular model.

Good luck!

Sir ODR wrote:

It's never been a great rider, has always started very harshly. I need to put it on full choke to get it started, and it needs to warm up for a good full 3 minutes before taking the choke off. When starting it always kicks out a bunch of whitish smoke too, which seems to go away after running for about 5 minutes.

So when it's still relatively cold it idles ok at about 1,000rpm's, but pops a lot. After warming up riding it for 15-20 minutes, the idle shoots all the way up to approx. 4000rpm's! Everytime I switch the bike off after riding for awhile, it backfires about 2 seconds after turning it off!

I have one idea too, sometimes a little gas leaks from the bottom of the float bowl, could this have gotten into the oil? I don't have any sort of overflow tubing running from the nipples, is there supposed to be?

White smoke is usually a sign of oil burning. It could be that your rings are getting weak, or a valve seal is gone and oil is trickling into the head after it has sat for a while. Oil in the cylinders can make starting hard.

Backfiring after shut down is usually excess fuel that's been pushed into the exhaust and is being ignited by hot exhaust/exhaust valve, if the rings were bad it could be loading up the pipes and loading up your oil. In it's attempt to keep running with bad rings it would be sucking in huge amounts of fuel which can't all burn.

((I have a couple of questions for you: Is it always the same side that smokes, or both sides??))

((Have you check to see if your oil level has gone way up or down, does it have a very gassy smell??))

I suggest you do a compression test, or get a shop to do one for you. It may be that your rings finally let go completely when it died on you the other day. Anything will run if you dump enough gas into spark.. well until it all ceases up that is.. heh.

---

If the compression checks out ok, it could just be the valve seal especially if the smoke is always from the left cylinder(when your sitting on the bike). It will still need repair but you could live with it til winter time then do a tear down. Well if you have winter.. lol

After checking that, Then I'd investigate the following.

Check the vacuum hose going to your tank for cracks, then inspect the other carb to see if the air nipple on it still has a good cap on it. If those are ok, while you have the tank off you should be able to remove the cap off the top of each carb (you can do this with the carbs on the bike) and inspect the diagphrams for rips or holes.

You should have drain hoses on the carbs yes, so that if it leaks fuel it goes under the bike on not on the motor or possibly the exhuast. The motor does have a drain spout on it though, so no the leaking fuel wouldn't enter your motor that way.

Let us know what you find out.

Wow, thanks for all the replies guys. It's been a busy week so I haven't had much of a chance to get out there and look at it, but am planning on getting to it this very soon.

@TexasKZ-

Have you checked the valve clearances?
I haven't, and am not sure a good way to go about doing it. Are there any good resources here for learning how to go about doing that?
Cam chain?
Yeah, I had my uncle take a look at it, he said it was all good. He's a motorcycle mechanic so I'll have to take his word on it.
Ignition system?
I assume you mean the plugs (and could be totally wrong), but they seem to be fine, nothing to note on them. Again, had my uncle take a peek and he said they looked good too. This is after riding it for awhile too.

@hocbj23: Airus leakus, lol, from reading around it sounds like everyone has had it at one point or another. Too much fun... :blink:

@smashadams:
About the air filter:I didn't originally have an air filter or air box that came with it, but after much searching found one and installed it. It had the foam which wrapped around the triangular piece, which seemed in good condition. I oiled it a little and put it in the airbox. It does fit well on the airbox, but I wouldn't say it is sealed, ie I can wiggle the airbox up and down just enough to make a little space. Are they supposed to seal tightly?
About the timing advancer: everything moves well and I just recently cleaned it.
About the gas: I will do that. When I open the tank up I can see what looks like specs in the gas, but otherwise the inside of the tank looks clean. I'll get an inline filter ASAP and install while cleaning out the carbs again, and will drain the gas in there just in case.
Luckily the bike did come with an old Clymer manual, which has made this work do-able. Thanks for the well wishes.

@CaptAmerica
About the rings: if this is the case and it is bad rings, does this mean the engine is done for? Are rings something that a newbie can replace?

Is it always the same side that smokes, or both sides??)

: If the bike is on the kickstand when starting off, which is when there is by far the most smoke, it seems to be coming from whichever pipe is higher up.

Have you check to see if your oil level has gone way up or down, does it have a very gassy smell??

: The oil level has gone down a bit, I just assumed it was leaking, which upon further inspection it is. Leaking from the bottom of the bike. Not sure where the exact leak is, and it seems to smell of gas. The carbs still leak a bit of gas too, which makes it hard to smell the oil because there is gas on top of the gear box. I will say that if the leaking stuff is oil, it really smells of gas.

About the compression check: will do that ASAP. I'll go to an autozone and see if they have the tool for it, I've heard you can rent them out for cheap.
Also will check out the hoses to and fro the tank. And we most definitely have a wintertime, and it seems to be fast approaching... live in the good ol' state of MN and denial of winter .

Thanks for all the helpful advice, I'm really looking forward to getting this old beast back up on the road running well.

I think you may have created your own problem.. chuckle.

I see you said you oiled up the foam piece for the air filter. It could very well be hard starting and smoking from the oil in the filter, if you applied to much oil. :silly: I'd fire it up a couple times without that filter in and see if she still smokes, if it's not smoking then and starts a bit easier, just wash that filter out with some gas, wring it out good and let it air dry. Then try running it dry in the bike.

If your uncle in a mechanic he probably has a compression tester, get him to do a quick test for you.

Everyone here is obsessed with checking valve clearances LOL, however your 440 has valve tappets (or whatever precise name ya want to use) and doesn't use the hockey pucks like most of the motors people are dealing with here. It is a simple procedure that should be well described even in a Clymer manual. The 440 has 4 caps on the top cover of the motor that come out easily allowing access to the adjusters, so a check of valve settings is very simple to do.

If your manual doesn't give a good description of it, there is a downloadable FSM at www.kz400.com/WorkshopManFrameset-5.html
Just scroll down to this line, and click on the highlighted (here)
(((A workshop manual for the following 440 models can be downloaded from here or here.)))


If it actually comes down to a ring job, no worries. No the motor isn't finished by any means. I'd say anyone with a manual could do a ring job, just out source the cylinder honing to an experienced mechanic/machinist.

OK so some new news, not necessarily good news but new...
I did a compression test this afternoon, and the right side (if you are sitting on the bike) has a reading of 125, while the left has 115.
I took the foam air filter out, and it was pretty well soaked in oil. I cleaned it out, put some new oil on and this time wrung the sucker out as well as I could, but noticed that the inside of the airbox, and the larger piece that it attaches to, both were slightly coated in oil! Crap... I'm hoping the no oil from the too oily filter got into the carbs! But it is a possibility considering how oily the inside of the airbox is. Could this possibly explain it's behavior? Before I replaced the filter the thing at least ran, not well, but it ran, but now I can barely get it started and when I do I have to open the throttle for the thing to even stay running. Did I possibly screw up the carbs?
A couple more strange things to note... I noticed when turning the thing over that white smoke would come out the tailpipes, that is without the bike even running.
AND I noticed the gas tank was completely empty too, I suppose this could be from the carbs leaking someplace, but I thought it was strange because there was no stain on the garage. Ooof, so much crap wrong with this bike! Capt.- thanks for the links to that service manual, that's some invaluable info right there! And for the last question of the day, how would I know if I need a ring job? Lol, alright, thanks again...