1980 KZ550 LTD carb issues

How do you get a reading on the fusebox? I can't seem to get one. And what did you replace yours with? And I checked that page out a big thanks to whoever took the time to compile all that info. And where is the primary/positive for the coil?

That page is Huge Thanks to member Loudhvx, he set that up and runs that web site.
Do you have a Volt meter to test with? If so Check the Battery voltage, then leaving the Black Negative on the Battery Neg, use the Red to test the Power both wear it comes into and out of the main Fuse. It should be almost Identical to the Battery measurement. If not if there is no sign of heat damage, you may be able to clean up the Fuse clips, and install a new fuse, AGX can be found at Napa. Otherwise get a new in-line fuse holder for the ATC style blade fuse and replace the section of fuse panel, with the In-line holder.
Then the Primary side of the Coils, that is where the small wires connect. The red is the power, the Green, and the Black are the signal to ground. What you want is to test the Voltage like before, black to Batt Neg, and Red now to Red wire. See if it is close to batt power, with Key On. If you had the voltage drop earlier at the Main fuse, it will continue through to each and every other circuit.

kaipederson wrote: ...where is the primary/positive for the coil?

Primary terminals aren't polar, so either wire may be connected to either terminal.

Good Fortune!

Alright thanks guys. I've got a Fluke mult so no worries there. I was trying to put positive on the fuses and negative on the frame so theres my problem. I'll let the battery charge and then take it off so I can get an accurate reading and report back.

So I just checked em and while the battery was recently disconnected from the charger I still took a reading for the heck of it. At the fuse box I saw about a half volt drop. A little more on the fuses for the tail light and headlight. Now at the coil I saw more than a volt drop. Good call guys. So should I attempt to restore the box or just buy new inline fuses? And I'd imagine I should also clean every friggin terminal I can find as well to try to get that voltage back up. Still startin right up on the 9.6 volts at the coil though.

Probably should Scrub off the surface charge after being on the charger. Just turn the headlight on for 15-20 seconds, then let the battery rest for an hour.
Also If you start the Voltage test with the Neg Test Lead on the Neg battery, then you should stay with that through the voltage tests. But you can also test the integrity of the Ground also. The Neg Batt cable will be the Ground for the starter motor, and the Black/ yellow stripe wire will be the Chassis circuit ground, for the bike electrical, Ign/ Lights/ etc.

I'll get back to you when the battery is done resting then with those voltages. Should I pick up some new fuses today?

A visual of the Fuse box condition will tell you a lot about whether you should stick with the AGX, or move to an In-line ATC. Just remember to stay with the recommended Rating, Always, Don't change the Rated Value.

hey bud,
i just took apart my carbs last week- alots a times i started on friday night at around ten then went in at 2 am because i was cold, then i went out again at 4 am and i got done in time to see people leaving for home from the olympia toy run. my first time with carbs and if anyone tells you "back in my day we did carbs all the time" or something along those lines just tell that person "well nowadays we have fuel injection." the reasons it took me so long to do the carbs(kz750 ltd h1) keihin 34x4)is not because they werent working but the overflow tube on the #1 cylinder was dripping constantly resulting in a wet smelly shoe and a partially stripped sparkplug thread from the hole in the cylinder head due to a lean mixture causing it to get hot. so sometime on that foggy saturday afternoon after the15th-or so time of installing and removing the carbs from the bike i decided to blow some air through the drain tube and held my finger over the other end with the drain screw in tight and guess what you will never believe this but the tube inside the carb was cracked. but now its worse because i adjusted the floats from where they were about 15 times with no service manual so once i retrofitted some fuel hose snug enough that i dont think i will ever get it back and i almost wrecked between stop lights (about 2-3 blocks) in a semi residential/suburbean area locked up the rear tire for about 20 feet to avoid running the stop light that has the notorious camera(partially due to the fact that when i checked my tire pressure it was 10psi up front and 20psi in the rear because of the cold. so now my throttle cable is worn out and where the adjusting nuts are by the throttle is busted so i wont be going anywhere until i find a new cable probably for the better because my before the carb repair lead wrist still hasnt adjusted to the horsepower difference i think i am going to have to completely overhaul the carbs now because if i cant ride the thing i have to do something with my overabundance of free time oh well maybe ill get a buspass/ yeah maybe not. ps this is a little inapropriate but i was tweaking the carb looking to find the fix and now they're worse off than before and i think i am going to be permafried on gasoline fumes

Nah don't worry I always love to hear stories. Alright a couple quick questions. My carburetor backfires could possibly be from poor timing, unsynced carbs, or valves, correct? Is it possible for it to tbe any one of the three? And also, for the fact that i'm losing over a volt to the coil, is cleaning up connectors going to alleviate that? That seems to be a lot for just dirty connectors. There aren't any internal resistors are there? I don't recall any on the wiring diagram. Thanks again

kaipederson wrote: ...couple quick questions. My carburetor backfires could possibly be from poor timing, unsynced carbs, or valves, correct? Is it possible for it to be any one of the three? And also, for the fact that I'm losing over a volt to the coil, is cleaning up connectors going to alleviate that? That seems to be a lot for just dirty connectors. There aren't any internal resistors are there? I don't recall any on the wiring diagram. Thanks again

I don't suspect lack of sync to be causing backfire through the carbs.

Would assure proper valve clearances and that static ignition timing is correct.

Also check integrity of ground connection where battery negative cable attaches to rear of the engine. And assure clean snug attachments of battery cables to the battery terminals. Negative battery post goes via cable to ground, and is best grounded to the engine as opposed to the frame.

Check for voltage drop at each connector, clean connectors as necessary and use Deoxit from Radio Shack or similar cleaner.

Here's an illustration of where to check the connectors:



Good Fortune!

Did what you guys told me and i've been riding it around for a little while now. Decided the other day to fix the exhuast leak. It had leaked a lot around the manifold so I ordered new exhuast gaskets. Took em off and didn't get a chance to touch em for about 3 weeks. There hadn't been any gaskets on previously which I found odd. So i put em all back together and tried to start it. Well i had forgotten to clamp down all the clamps. So I screwed em down. Sadly one of my bolts coming from the block to secure the pipe broke It still protrudes out a good bit, it only lost about a 1/4". So with everything tightened down I went to start it. Didn't start super easy and now its got something odd with it. It runs just fine at above 2500 rpms but any lower and it dies. Any ideas? Could the idle jets have gotten dirty from sitting for 3 weeks? The garage its in is heated but its not much above freezing. And how about that exhaust bolt? I appreciate all your help guys its been awesome! Oh and also the bike seriously just won't start with anything less than like a 3/4 turn out on the fuel/air mix screws. Thanks!