81 GPZ550 now running, but won't take throttle

Good morning guys. I finally got my 81 GPZ550 project to run this morning! She fires up and idles nice, but will not take throttle(just a tiny bit, then dies), need a little help figuring out why. I believe all cylinders are firing, it runs very smooth and all 4 exhaust pipes seem uniformly hot to the touch. Im pretty sure the carbs are clean/working properly - I've broken them down and cleaned them 4 times and believe that all passages are clear. Originally my carbs had 2 of the air/fuel screws uncapped, the other 2 still capped. I removed the caps from the remaining 2 and checked them all, they were all at different settings that varied widely. I think the manual said they should be set between 1 3/8 and 1 5/8 turns out, so after replacing their o-rings, I set them right in the middle at 1 1/2 turns out. The aircleaner I'm running is a slightly modified breadbox from a CB750. I have both the bottom crankcase vent and the top vent from the rocker boxes plumbed into the breadbox. Foam filter element, with the sides taped up (as per a CB750/breadbox article I read about optimizing performance and minimizing sidedraft issues). I'm running a 4 into 1 header from a kz650, tweaked to fit. Open header, don't have a muffler to fit it yet. So taking into account my breadbox aircleaner and the open header... where would I start in getting it to take throttle? Adjust the air/fuel screws? How so? Any other ideas? Super excited to finally have it running (it's been an uphill battle!), and eager to move forward. Any input greatly appreciated. Thanks!

PS - question about the 2 carb "vents". A tk-22 carb diagram I found says that I should have a long hose attached to each of the 2 vents and run them up under the gas tank and leave them open. BUT - originally when I took the bike apart, those 2 vent hoses went to a "T" fitting with the remaining hose going to to the small nipple on the little vac canister under the frame backbone that the 2 top rockerbox vents go to. Right now I'm running the carb vents open at the carbs, and have nothing connected to the small nipple on that vac canister... what is correct here? Should I put the vent hoses back into the T fitting and run to that vac nipple? Orrrr....?

Do some searching here and elsewhere on carb tuning, try to get your main jet right first, then needle position, then pilots if you need.

My tk22 81 GPz50 was running on I think 102.5 or 105 , expect to upjet on your mains for that set up. Slide carbs are easier to tune than the later CV type.

Don't pay too much attention to the manual pilot airscrew settings, particularly when running non standard pipes and intake. Just set it for the best , and do this bit last. Work top down, starting with your main jets and wide open throttle (WOT).

You need a vac pipe to work the fuel tap, there are also overflow pipes and vent pipes that often
get left out. I think there are vac take off on the inlet rubbers, these need to be plugged or linked.

I have a stock '81 gpz550 and would say your air screws are set too lean. Have all four of mine set at 1-1/8 and that is okay on my stock bike. The more you turn those screws out, the leaner low speed mixture gets. Would recommend you start with one turn out on all four. You will likely find your main jets a little lean. Might start by shimming up your jet needle with one small washer. Would first try it with your air screw set at 1 turn out and see if that helps.

Thanks for the input guys.

Tyrell - I have the large vac port on the far right side intake boot (the one that goes to the petcock) plugged. Don't even have a fuel tank installed at the moment. The 4 small vac ports on the intake boots used for carb synchronization are also plugged. The carb vents I was asking about are the horizontal tubes that "T" in between carbs 1&2, and 3&4. Not sure if I should leave these open as stated in my carb diagram, or if I should T them into that vac nipple on the small canister right above the rocker boxes like they were when I first disassembled the bike.

Gpz550D1 - Thanks for the useful information, much appreciated. I'll try turning the air screws in, and experiment with some different settings. You told me what I needed to know, really. I wasn't sure which direction would make it more lean and which would enrichen it. It's definitely idling lean, judging by the spark plugs which were brand new and the fact that theres pretty much no fuel smell or smoke to the exhaust. I'll see what I can do messing with the air screws alone, then try shimming the needles like you said. I'm just going to use the smallest flat washers I can find that fit the base of the needle, correct? Also I'm bringing home a universal "shorty" type motorcycle muffler (free flowing, but baffled... like a little cherry bomb) with me from work today, so hopefully that will help swing things a bit more in my direction once I get it clamped onto the header. Wasn't really planning to ride it with no muffler, just didn't have one at home this morn when I got her fired up. I'm hoping to get it running properly (more or less) without having to change jets if possible. Money is tight and so is time, but I'll do what I need to in order to get it running properly. Thanks again.

I'm going to try to add a video of the startup this morning, not sure if it'll work... just for the hell of it...

Yes, just the smallest washer you can find. Stock main jet is #94 and you may have to go up on that, but you can try raising the jet needle. Try the air screw first and see how it does. Also, you can give it a little choke and see if it will run better. If it does, then you know for sure you are too lean. Don't think you have a vacuum leak anywhere, since you say it idles good. Good luck!

Below is a link to Lou's TK-22 carburetor information page, which you might find useful.

home.comcast.net/~loudgpz/GPZweb/TK22mainPage/TK22mainPage.html