Syncing issue or much more?

Hey all, I'm new here since I just found this place existed and I could use a little help.

I picked up a 1982 KZ 440 LTD D Belt and am having some issues and I'm not sure what is causing them. I would have used the search but I don't know what my problem is exactly. I will list my symptoms and what I have done, and how it turned out and maybe someone can tell me what to do. I appreciate any and all help I can get!

Symptoms:
Bike starts fine on full coke and idles high.(tach is broke, that's another issue, but I can just tell when comparing it to the feel of my kz550) The idle screw is backed all the way off so it's not just adjusted high. If I let the bike warm up it idles higher, often too high for my comfort. I can drive it around, giving no throttle when it's choked.

For example, today I fired it up, let it sit for maybe a minute, then drove it down the street, maybe went 300 yards and it started idling higher, so I unchoke it, and it almost kills it. Then when half choaked (so it wont die or idle too high) if I try to give throttle the bike moans and boggs down and dies. Also throttle is VERY slow to respond, off by up to 2-3 seconds. If I drive when the idle is on partially (to keep it from dying) I get a very jerky ride. It's like little bursts of energy.

I have tried cleaning the carbs multiple times. The first time, they were a little dirty and one float needle had a huge piece of dirt stuck to it, cleaned it all out and it ran good for maybe 10 minutes (could have been just before it warmed up and I was so excited / exhausted my brain just wanted it to work) I went through and did a more detailed cleaning and I found no new material, blew all the lines out, cleaned it spotless! Still no better. I have done a lot of research on this, carbs are VERY new to me, and I think it could need a syncing, but I did just a bench syncing, (following video below) the valves look to exactly match, not sure how precise it needs to be but I don't own the vacuum gauges needed to test that.

I can have the carbs synced at my local shop but they want around $160 for it, and I don't want to throw that kind of money at this bike unless I am certain it will fix it.

Extra Info:

I am using these air filters and stock exhaust.

Bench Syncing

don't let the rpm go above 2000 rpm with the choke on. get a tachometer cable and clean/replace the spark plugs.
the choke primes the fuel system when it has been sitting and "warms up the engine"
you may run into a leaky vacuum petcock-i.e. the vacuum nipple will leak into the intake and ruin that cylinder. .

I installed a new Tach cable since it did not come with one, and when the engine is running it goes up, it's just highly inaccurate and I'm not sure why.

I also installed new spark plugs so that wont be the issue.

As for the petcock, I just rebuilt it, and it's not leaking at all but I can't figure out where to connect the vacuum hose to, I think it goes somewhere on the carbs right? Right now I'm just running it in prime.

yep, right on the vacuum nipple.

If I'm only putting it in prime when I'm running then that shouldn't be my issue.

Any other ideas?

for a minute I thought you were going to sink it in the bay.

Kindof sounds like a vacuum leak at the intake maybe. If it runs better w choke on than off its got to be either a clogged port in carbs or a vacuum leak somewhere.

This video only shows syncing the butterflies. Not the air circuits. If ur air screws are still capped off might try removing the caps and screws to clean those ports. Be sure to run the screws in all the way first to see how far out they were set from factory. Mine were all different settings so I set them at 1 1/2 turns out till I could put the guages on them

run a can of cleaner through the gas using the choke for a while when it is idling it should pull everything through there. then change the oil.

This video only shows syncing the butterflies. Not the air circuits. If ur air screws are still capped off might try removing the caps and screws to clean those ports. Be sure to run the screws in all the way first to see how far out they were set from factory. Mine were all different settings so I set them at 1 1/2 turns out till I could put the guages on them

The air screws are the screws located on top of the carbs near the inlet to the engine, correct? If those are the ones you're talking about, I cleaned them, and they were both set at exactly 1/2 turn out. Do you recommend me turning them out about 1 whole turn more?

I could just go buy a carb sync gauge kit, it would be cheaper than paying a garage to fix them.

magruder13 wrote:

I could just go buy a carb sync gauge kit, it would be cheaper than paying a garage to fix them.

And you get the benefit of using them again and again in the future whenever you want to.

take the carbs off and put toothpicks under the throttles and close them to see what toothpick is more dented.