TOPIC:

Hello, I'm new to the site, and new to motorcycles. I've searched the forums and found similar issues. But nothing quite like mine. Any help is greatly appreciated as I've been going crazy trying to figure this out. First things first, I got a 1984 kz550 ltd about a month ago, when I got it it ran great except that the carbs were leaking into the crank through the airbox. So I give it a nice cleaning and still leaks. I go ahead and get some rebuild kits from a local bike shop and proceed with that. Then it won't start unless choke is pulled out. And dies when pushed back in. Smh. Take it to my father in laws friend and he gets it started. And it idles real nice. I get the bike legal and run it down the street it bogged a little during accel, and stalled out while letting off throttle while downshifting. Issues resurfaced. Reached out to my old auto teacher from my highschool days. Adjusted float height to 7mm from seam, air screws are 1.5 turns out. Even went 2.5 and no change. When I start it with choke on its 3k rpm, IF I can get the choke off and accel while idle its boggy in the beginning then clears up, also seems like it takes longer than usual to go back to a low rpm for idle. Most of the time if it idles with choke off if I even play with the throttle it bogs right out and stalls. Please someone help, I'm going crazy over this. I just want my bike running decently so I can get my endorsement and be able to ride.

There are so many things it could be, but it is most likely to be the fuel. I'm an advocate for reading spark plugs - if you can get it to run without the choke for a while, check the spark plugs after you've let it run for 5 minutes. They should be a light brown colour. I expect that they are a white colour, which would be lean.

As a general guide, running lean will result in an erratic idle, bogging down on acceleration (if you flick open the throttle, it will die) and can stall on dropping the throttle. If running rich, you will get a rhythmic misfire at idle and it will bog down at higher revs.

Is it rideable with the choke on? How about half-on? If the answer is yes to either, then you need to enrich your mixture.

CV carbs? Pics. If so do the thumb test. Might be bad diaphragms.
Steve
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672948

Thanks for the replies, spark plugs seemed fine when I got it, I've also replaced them and checked them and I think were a little black. I'm unsure of the thumb test, so I can't do it. Also do either of you know the proper float height? Or fuel level? And a good amount of turns for the pilot screws?

Those are the same carbs. The thumb test is lifting the slides while holding your thumb over the large vents in the back. If they go down slow, runable, fast, not. Make sure they don't stick. The pilots were so small a guitar string wouldn't fit. Read my post on how I dealt with it. The screws control the fuel at idle.
Steve

Also look up the clear tube test.
Steve

Reading your original post indicates to me that you initially had sticking float valve/s (staying open ) which caused the carbs leaking problem.
Sounds like something (else) went wrong during the fitting of the carb rebuild kits and it now sounds like a fuel starvation problem
- possibly still due to the float valves;? This is maybe because the "choke" is not really a choke but an enriching system and initially may be the only fuel that is getting through, and is why it dies when choke released.
The return of the problem after a period of it running ok indicates that maybe it's still with the float valves - maybe sticking shut/wrong size/incorrectly installed.

Also don't discount something else "obvious" which was inadvertently disturbed during the carb kit replacement and is adding to your problems - check for a pinched fuel feed line or tank breather pipe?

Well I tried thumb test and they seem to go down at the same speed plugged or not. Don't know if that's a problem or not? I thought the issue was a chip on the underside of where the air screw pokes out. Jbwelded the hole. Issues are still present. New float needles and valves. Same problems. High idle with choke on. Dies while taking off choke. I have another very similar set of carbs a friend gave me off i think a gpz Same body but an extra jet and the pilot jet has a cap on it?? And the main jet is an 86 vs mine 120. Will try those but they were very gummed up and gunky. So I'm getting those cleaned out. Who knows.

After putting the other set of carbs on. They pop. I'm guessing they're too lean, either by the main jet maybe? Being smaller than mine? Or what? I don't know, maybe they aren't clean enough? I usually don't get defeated on mechanical issues, but this is my first motorcycle and first carb job, I've learned alot. But a shop seems like an easier way out but they are all about 1-2 wks out. I don't wan to go to a shop I'd like the original set on running good like it did before I tried fixing the leak, which could've been prevented from the get go essentially by just rebuilding petcock as it was leaking. Now I've got a mess and don't know what to do, I've tried everything it seems like.

Unless the carbs you have just tried are set up properly for your bike, you're going to have another set of issues to deal with as well as the original ones.
Still think that something has been introduced/changed during your re-installation of the carbs after the initial repair of the fuel leak ( it was running fine except for the fuel leak - right...?) Probably need to re-fit the original carbs and try to get your setup as close to it was originally to set a baseline for fault-finding. If you're running a fairly standard air/exhaust setup then stick to the OEM jet sizes and float levels etc to try and eliminate any side issues.
The "popping" sounds like a fuel/air mixture problem - maybe there's a small leak around the inlet manifold area and the engine is sucking extra air? Perhaps the inlet manifold is perished and the final straw was the removal of the carbs to fix the leak and the hardened manifold has split, allowing additional air to be sucked in?
The instances of "now it goes, now it doesn't" during the repair attempts could be because this work has openend/closed some cracks in the manifold and thus the intermittent problem.

No eBay APP ID and/or Cert ID defined in Kunena configurationYour pilots are clogged. I had to use my smallest jet drill to clear them.
Steve

I'm just confused, all I did was get some rebuild kits k&l 18-2461, replace pilot jet, float needle, needle seat, air/fuel screw. Bowl gasket. Only thing I can think is besides vacuum leak. The a/f screw. The carbs were taken care of from previous owner. They were already clean, but of course I blew air and cleaned them when I did the rebuild. Only thing I can think of besides the intake leaking is the air screws. How many turns out should they be? I've tried at 0, 1, 1.5, 2, 2.5 I've sprayed carb cleaner around the intake boots a while ago and didn't seem to have any effect on idle.