Engine Running Funny

[fireman]

Hi all, new to your site and did some reading on the forum and it looks like you all are helpful to each other.

Well in that respect i need your help as well and will help you if possible.

My problem is a 1980 Kawasaki KZ750H LTD. Yeah i know it is old but, like the bike and want to get her well again.

Problem is engine is a little rough to start. Engine seems like it is only running on 3 cylinders rather than four. When i pull the throttle, engine revs up. When i let go of the throttle it revs down, but real slow. When it was ridable it did the same thing, but once engine got warm, the other cylinder started to work. Now, when engine is warm it still does not kick in. I have done some checking on my own but, i keep coming up confused. Reaching in the wind for answers here are the things i checked or tested.
*Cylinder compression check cylinder #1 @145 psi
cylinders #2,3&4 135 psi
acording to the repair manual this is with-in range, and no more than 14 psi between any two cylinders.
*Ignition coil did ohms reading of primary & secondary windings, that tested out with-in range.
*Pulled off carbs everything looked ok on them. But, the #1 cylinder carb to engine boot looked a little messed up. So possible compression leak there.
Has fresh gas, and was tuned up recently. I do however question plug wires. I had to put them together, so possible not a good connection.

Thanks in advance
fireman

[brancher]

Been a long time since I worked on a ujm. But if it helps, I always get better results by eliminating the obvious:

1. Get new plugs and wires. Install the plugs per specs.
2. Get another boot for cylinder #1, install.
3. Pull tank, check all hoses in engine frame for any cracks, stiffness, etc.
4. while you're under there, shoot some WD-40 on all moving throttle parts, like the idle mechanism, etc. AFter that, wipe the WD-40 clean and follow up with a spray lubricant that will provide for quality mechanical movement.

Reassemble, and try it again. This isn't a comprehensive list, but should get you started. Hope it helps.

[virtualkuz]

i would pull the valve cover and check the valve clearances. a carb synchronization might be helpful too.

[fireman]

I replaced the plugs and wires but, i still need to get new wires since I'm not sure about them. While i am at it, i might as well replace plugs too.

I will also get a new boot for #1 cylinder.

Here is another piece to the puzzle. I put the carbs back on, as well as everything else. I did leave the air box off, just to see if there was any difference. While the engine was running at higher than idle rpm's, I was getting a mist out of #4 carb, choke valve. It was not a steady mist but kind of a backfire sound when it came out. So i don't know if that is an indication of a valve problem or not.

[Gpz1100]

Had the exact same problem on a '76 LTD 1000. Rebuilt the carbs and sync'd 'em. Took care of a whole lota other small problems.

[fireman]

Did it help your original problem, or just the mist from choke valve

[Gpz1100]

Carb rebuild and sync fixed the rough idle, slow return to idle, running on 3 cyl, backfire and misting. That intake boot could cause a vacuum leak and also affect performance. Also check the battery for a dead cell or low voltage. That can cause a miss and rough idle. I had a battery with a bad cell that would still start the bike and after replacing it the bike ('81 CSR 1000) ran beautiful and never missed again.

[fireman]

Well, I quess i am going to do just that. Sounds like the same problem that you had.
I am going to rule out the battery, it is brand new. thanks

[QKENUF4U]

sounds like GPZ has ya on the right track.
other things i would check on #4
THE CARB BOOTS to make sure they are not cracked in any way/DRYROTTED
the rubber lines are in good shape and have no vacumn leaks
that the diaphram is in good shape
that the fuel screws are set correclty and not leaking (you can spray carb cleaner on them while the bike is running to check this)
sounds to me like that cylinder is running lean on ya (no fuel)
easy way to eliminate the carbs as a problem is to spray carb cleaner in the dead cylinder while its running to see if it fires off. if it does then its a fuel delivery problem if not then its spark
good luck

[fireman]

thanks all, unfortunately the bike is going to have to wait till next weekend.

[kawasakikid38]

yea fireman, gpz has you going in the right path. it soulds like carb problems to me. lets hope these guys can help.

[Gpz1100]

Hey fireman! Did ya get 'r done? Any update?

[fireman]

UP DATE

After everybody replyed to my posting I did and checked more stuff. When i rechecked for spark, to me it seemed a little weak. So after searching for loose connections the only thing i came up with, was a corroded negative battery cable. When i replaced the battery acouple of months ago, it was not corroded. I started the bike 2 days in a row, all was well. Yesterday (Saturday) put everything back together and was going to take it for test ride, the engine was idling at around 4000 rpm.
Throttle cable was working properly and returning back the whole way, and idle adjustment wasn't making a difference when i tried. Now i gotta figure out whatb is going on there. I am going to take the bike to the shop and get the carbs resynchronized(i quess that is how you spell that) any more thoughts.
Thanks Gpz1100 for asking for a update

[QKENUF4U]

one BIG OL vacumn leak, a slide hanging open, cable not returning like you think it is, choke on

[kawasakikid38]

hay fireman sorry to here that. and you was so happy at work and now this. BUT, don't give up dude just do the best you can and she'll come around. i'm at a stand still too. but mine will be running better soon too. once the funds are their. but for now, i'll just look at it and dream.lol. see you at work dude. ps. can't wait till we both get our kz's running and go for that nice ride. c-ya