Idle is "hunting" / 83 KZ550

Picked up this bike a few days ago. It's a 83 KZ550 A. Guy said it sat for two years, so I dumped the tank, rinsed with gas, refilled, added a dash of Techron carb/injector cleaner. Got it running a bit cleaner, found a hole in the floatbowl hose on top of the carbs, fixed it.

Now the bike starts first try with the choke almost all the way in, but RPM needle floats around + or - 500RPM. Engine stalls when chokes all the way in.
Also noticed if I pinch the floatbowl hoses with my finger the RPMs go up. One last thing, it makes a "burping" noise when you rev the throttle. If you keep revving, it will gas it after a few quick bursts and RPMs go up as normal, then back down.

So, the question I suppose, is this a vacuum issue on the carbs or are the needles dirty?

Here's a video of it running with the choke out all the way and revved, then pushed back in. Most of the way and revved: mobile version: m.youtube.com/#/watch?v=0wni4hnaqfE

It looks like you have pods on a KZ550 with CV carbs = bad joo joo.

I can't imagine that those carbs wouldn't need thoroughly cleaned after sitting for two years! Do yourself a favor and dissassemble the carbs and dip them in Berryman's for 24 hours each and clean them thoroughly. There must be a carb cleaning tutorial on here somewhere. Perhaps there are some o-rings that need replaced in there. Also, make sure the carb boots are still pliable and don't leak. I would also just replace those. Clean the air filter(s) and be sure this is also sealed properly. This will give you a baseline to begin deciphering fuel/air-intake issues. Until you do this, you are just guessing.

Using Seafoam, or even taking off carbs and squirting with carb cleaner will not get all those tiny passages clean after it's been sitting and is gummed up.

bugsinmyteeth wrote: I can't imagine that those carbs wouldn't need thoroughly cleaned after sitting for two years! Do yourself a favor and dissassemble the carbs and dip them in Berryman's for 24 hours each and clean them thoroughly. There must be a carb cleaning tutorial on here somewhere. Perhaps there are some o-rings that need replaced in there. Also, make sure the carb boots are still pliable and don't leak. I would also just replace those. Clean the air filter(s) and be sure this is also sealed properly. This will give you a baseline to begin deciphering fuel/air-intake issues. Until you do this, you are just guessing.

Using Seafoam, or even taking off carbs and squirting with carb cleaner will not get all those tiny passages clean after it's been sitting and is gummed up.

Thank you bugsinmyteeth, that is exactly what I'll do. Per suggestion, checked the boots and the two center boots on the intake manifold are leaking. Next step is disassembling and cleaning.
Thanks for your help.

You are welcome. I hope you are able to eliminate all the problems. Let us know how it goes. Also, let us know if you ended up addressing some other things. We learn from shared experience.

bugsinmyteeth wrote: You are welcome. I hope you are able to eliminate all the problems. Let us know how it goes. Also, let us know if you ended up addressing some other things. We learn from shared experience.

I got the boots and clamps in yesterday from Bike Bandit, replaced those. Sprayed all vacuum points again for leaks and nothing.
It's idling better but still runniong sporatic. I'll clean the air filters and my friends going to clean the carbs.
Will update this again after that's done!

Got her fixed up and running great.

Once the carbs were opened you could see a green tinge over everything.
The o-ring seals on the carbs were sealed with some gunked up yellow elastic crap which was cleaned off and removed. Whoever was inside these things pinched an o-ring in the carb housing so there was a leak out the bottom.

Removed the jets which are 135s, they were clogged. Soaked the jets, pins and everything removable from the carb in carb cleaner for 30 minutes, blew the jets out with an air compressor afterward. A few of the jets were clogged.

The other main problem was that the floats were set way too high, so whoever rejetted this didn't pull it off properly. I set them to 27mm as per the manual says and it sounds very nice now and runs like a charm with the choke all the way in. The needle on the RPM is only hunting up and down a hair (literally) but I think it needs to be rode a bit more to let the rest of the carb cleaner in the tank flush it out. If not then maybe do a bit of tweaking.

The next step (after finally getting to ride... :woohoo: ) is going to be restoring the factory airbox (which I have, thankfully) and rejetting back to stock. Can't wait!

Mk508 wrote: ...floats were set way too high...I set them to 27mm as per the manual says....

Would confirm correct fuel levels by performing the clear tube test on each carb.

Fuel level is the critical spec -- not float height.

Good Fortune!

Mk508 wrote: Got her fixed up and running great.

Once the carbs were opened you could see a green tinge over everything.
The o-ring seals on the carbs were sealed with some gunked up yellow elastic crap which was cleaned off and removed. Whoever was inside these things pinched an o-ring in the carb housing so there was a leak out the bottom.

Removed the jets which are 135s, they were clogged. Soaked the jets, pins and everything removable from the carb in carb cleaner for 30 minutes, blew the jets out with an air compressor afterward. A few of the jets were clogged.

The other main problem was that the floats were set way too high, so whoever rejetted this didn't pull it off properly. I set them to 27mm as per the manual says and it sounds very nice now and runs like a charm with the choke all the way in. The needle on the RPM is only hunting up and down a hair (literally) but I think it needs to be rode a bit more to let the rest of the carb cleaner in the tank flush it out. If not then maybe do a bit of tweaking.

The next step (after finally getting to ride... :woohoo: ) is going to be restoring the factory airbox (which I have, thankfully) and rejetting back to stock. Can't wait!

Good job, MK508! It's amazing how well these old bikes will run after a bit of routine maintenance gets them back into condition. Starting with the basic maintenance sounds boring cause we want to get on and ride, but it is much more fun to ride a bike that runs well.

bugsinmyteet wrote: Good job, MK508! It's amazing how well these old bikes will run after a bit of routine maintenance gets them back into condition. Starting with the basic maintenance sounds boring cause we want to get on and ride, but it is much more fun to ride a bike that runs well.

Thank you. I've never rode before, first bike here... very anxious to get it running but definitely want to make sure it's done properly so no issues are encountered. So far it's been pretty easy to work on!

Patton wrote: Would confirm correct fuel levels by performing the clear tube test on each carb.

Fuel level is the critical spec -- not float height.

Thanks to everyone for your help, I really do appreciate it as I do not know what I'm doing.
I didn't start the bike since the last post 'til yesterday and had to pull the choke entirely out then it took about 10 minutes to get it idling steady. It stalled a few times when I took off but then ran OK.

Started right up today but only with choke all the way out and idled at 2k. Rode up and down the street a few times and the idle was still 2k with choke all the way out... but it wasn't fluctuating wildly like it was yesterday so that's a good sign. Today I'm going to pop the carbs off again, check the jets, clean again if necessary and then do the clear tube test.

One question out of curiosity, is a KZ550 supposed to idle at 2k or is the idle specific to each bike or setup? Can't find that in the manual. It sounds too low and "rattly" at 1500 and too high at 2500 so 2k seemed proper.