i am an idiot... please help!

Gintree, not familiar w/your carbs but offer these tips. if mixture screws are between air filter and carb body, they are air screws. in is rich, out is lean. if screws are between carb body and head, they are fuel screws, in is lean & out is rich. hope this helps G

Gane, I prefer to call the screws you refer to as fuel screws, pilot mixture screws. If you trace the path of the pilot air jet and pilot jet, the air from the pilot air jet and the fuel from the pilot jet both egress in a small hole(s) in the venturi so it is actually a mixture of air and fuel where the air screw you described, controls the volume of air that mixes with a fixed amount of fuel from the pilot jet. Just a note of clarification. Gane was correct on how to adjust the screws. FWIW: This is why air screws sometimes seem to have minimal effect on the mixture when tuning... the slide cut out is adding air in a fixed amount at idle; probably a lot more air than the air screw which may just be there to aid the fuel flow as opposed to affecting the air/fuel mixture.

Gane and WG, Thanks!

I was talking about the air screw (between air filter and carb body). So I turned them in some and it seems like it runs a little better, but it feels like it is still bogging down some when I take off. I have to give it quite a bit of throttle to not stall out when taking off. The bike seems like it runs pretty good when I get on the throttle, but not at lower throttle levels. Is this evidence of a lean mixture at low throttle?

From what WG said, the air screw doesn't have all that much effect on the mixture, so should I up my pilot jets?

BTW, these are round slide carbs off a 1980 kz550 and I don't think they have pilot mixture screws... at least not that I saw! I'm pretty new to bikes and very new to carbs so any advice on getting my bike running right would be great.

Thanks for the help!

George, your're right, I stand corrected. My terminology was of my own invention and allows me to keep them straight in my mind. Gintree.. In my experiance, if air/mixture screws affect idle speed within acceptable adjustment range, say at least 1 turn out & less than 4, pliot jets are within range. experementing does no harm, but you might try shimming/raising needles 1st . G

There were two 550 LTD's in 83.
The 550 M(I think) LTD shaft version
And the 550 C4 LTD chain version.

Since you say you are using 1980 550 carbs, I assume you have the chain version. That uses the Teikei TK22 carbs.
Those carbs are simple round slides with a main and pilot jet, and a single air screw. Air screw: out goes leaner, in goes richer.

The main was 92 and pilot was 32. The needles are not adjustable (adding a shim will bind the needle and cause wear). The commonly available rebuild kits from K&L come with adjustable needles, 92 mains and 32 pilots. The mains are the same as small Keihin mains.

Let me find a link to more TK22 info than you would ever want.

kzrider.com/index.php?option=com_kunena&...d=3&id=175890#175897

Heck I'll just repost what I have.

Here's a comparison of the various available needles.

All TK 22 carbs are same except main jets and needles.
The number after the dash in the needle number represents the clip position from the top (out of 5).
The 4D92 needle is the same as the 4D93 needle set at clip position 2 from the top (out of 5).
Canadian 550 models use the 4D93 adjustable needles.

Supposedly, slides with different cutaways exist, maybe for racing, but all of the KZ400, KZ500, and KZ550 with TK-21 or TK-22 carbs used the same slides.

The USA models have plugs over their air-screw openings, so the air-screw setting is in parenthesis since they are not officially accessible. The KZ550D model carbs are also painted black.

This chart represents the models using TK21 or TK22 manual-slide carbs. Later models with CV type carbs are not represented here.
The same bikes, made in subsequent years, using the same carbs most likely have the same internal setups. For example, the 1981 KZ550C2 and 1982 KZ550C3 would have the same setup as the 1980 KZ550C1, because they also use the TK22 carbs. However, the 1983 KZ550A4 uses different carbs than the 1980 KZ550A1, so its setup would have to be different.

Note: All models with TK21 and TK22 carbs have the same pilot jet, slide, and fuel levels.

The West German 550 model is puzzling since it is listed as having the smaller carb, yet the 500 has the larger carb. Maybe it's a typo in the FSM.

Year Model TK carb Main Needle Clip Pilot Air Screw Slide Fuel Level Fuel Level
Jet From Top Jet Turn Out Cutaway Design Service
1979 KZ500B1 K22P-2A 90 4C91-2 2 32 1-1/8 +/- 1/4 2.5 29.5 +/- 1 mm 3.5 +/-1 mm

1980 KZ400J1 K21P-2A 90 4C91-2 2 32 1-1/4 +/- 1/4 2.5 29.5 +/- 1 mm 3.5 +/-1 mm
West German K21P-2A 92 4C91-2 2 32 1-1/2 +/- 1/4 2.5 29.5 +/- 1 mm 3.5 +/-1 mm

1980 KZ550A1 and C1 K22P-2D 92 4D93-2 2 32 1-3/8 +/- 1/4 2.5 29.5 +/- 1 mm 3.5 +/-1 mm
USA K22P-2C 92 4D92 No Adjust 32 (1-3/8 +/- 1/4) 2.5 29.5 +/- 1 mm 3.5 +/-1 mm
West German K21P-2A 90 4C91-2 2 32 1-1/4 +/- 1/4 2.5 29.5 +/- 1 mm 3.5 +/-1 mm

1981 KZ550D1 K22P-2F 94 4D93-2 2 32 1-3/8 +/- 1/4 2.5 29.5 +/- 1 mm 3.5 +/-1 mm
USA K22P-2E 94 4D92 No Adjust 32 (1-3/8 +/- 1/4) 2.5 29.5 +/- 1 mm 3.5 +/-1 mm


K&L rebuild kit 18-2462 comes with Y77 needle which is same as the 4D93 needle and second clip from top matches the 4D92 needle. It also comes with main and pilot jets almost identical to stock TK parts.

Pilot jet is 23.5mm long with M4 x .7mm thread.
Main jet is hex head 7.8mm long with M5 x .8mm thread.

The carb-center spacing is the same 81 to 83, but the ports are bigger on 82/83. The 81 manifolds will work on 82/83 if the screw holes are notched outward and use a heavy washer. Supposedly all 4 manifolds are the same on the 81 model, but they look different due to sag over time. Orient them to work together and to get some lift on the carbs.

Here's a link to a mod for the choke system which might help on cold days.

www.geocities.com/loudgpz/GPZchokeScrewMod.html

96 mains sounds about right. You may find the screws end up 1/2 or 1 turn out. If they are less turns out than that, you may want to drill the pilots to 35 (or 37 if still having problems). But before that make sure you have the float levels set properly per the manual. (I can post an online manual if you need one.)

I hope you have a chain LTD or all of this is irrelevant.

:woohoo: :woohoo: :woohoo:

That's what I needed! Thanks loudhvx, Gane and George! The bike is a chain LTD and the carbs have the non-adjustable needles.

That's a lot of info so let me know if I got this straight:

-First I'll do a more in-depth attempt at setting the air screws.

-If I'm still having trouble, try drilling out the pilot jets.

-If I'm still having trouble, get adjustable needles and set the needles up a clip position from 2 from the top to 3 from the top.

I'll keep yall posted.

loudhvx - once I get these tuned up, I'll give the choke mod a go.

Thanks again

gintree

If the bike is lean coming off idle (like when launching the bike from a stop), shimming the jet needles won't be of much help. Look at the fine jet needle drawings provided by loudhvx. The taper of the jet needle is the same when raised by the thickness of the shim. I am NOT a fan of trying to drill jets because it would require a drill press and precision drill bits but in this case, since Tekei pilot jets are not available in a larger size, it might be the best route. Keihin CV34 carbs have much the same issue. They use a #35 slow jet (same as pilot jet) and there are no alternative sizes. In fact, I can't find replacement #35 slow jets so the alternative is to clean the slow jet but in the case of the CV34, they offer a separate mid-range circuit which is augmented by what they call the MAIN JET which is really a mid-range jet and works in conjunction with the jet needle so richening this MAIN JET some really compensates well for the leanness off idle. Tekei doesn't have a way to do it so drill the pilots would be about the best way to accomplish this. If there was enough demand, I could request larger Tekei pilot jets could be fabricated by the Japanese manufacturer but I would probably have to buy a LOT of them and I doubt they would ever move in sufficient quantity.

Hey Wg, I think you should give drilling jets a try. It's actually really easy. I've done probably several dozen. I don't use anything special. Actually the best drill for the job is the cheapo $15 tool shop drill at Menards. The reason is because it can set a very low variable speed and most importantly the chuck closes all the way down to zero.

I lightly mount the drill in a vice, it doesn't have to be very secure because it will be very slow and it's only drilling brass. Also the hole is so small there is almost no torque on the drill. And remember you are not really drilling a new hole, you are just slightly reaming an existing hole so there is very little stress on the bit. Then I lock the trigger and slowly increase the speed dial on the drill. When I get about 1 to 5 revs per second it's ready to go.

I used to use a flexible piece of vacuum tubing to hold the jet so it would be free to self-center on the bit, but lately I've been lazy and just holding the jet in my thumb and forefinger. The larger jets practically drill themselves, meaning no pressure needs to be applied. The pilot jets take a little more care because the bits are so tiny. The only time you might have a probelm is if the pilot jet has some corrosion in it. Then the bits can get dull. But the key is go as slow as possible on the drill.

Since pilots and mains are available in the smallest size in the rebuild kits, they are very plentiful. Not to mention, the TK22's seem to be the most plentiful carbs out there for KZ's since they were used on so many 550 and 500 models.

The super tiny bits I use are usually available at hobby centers. The bits in the 94 to 102 range are a little more difficult to come by. Usually they are in the letter gauge sets.

The reason I don't recommend shimming the needles on the TK22 is that I noticed the shim locks the needle in place instead of letting it wiggle slightly. This can cause it to rub off center in the needle orifice causing wear on the orifice and needle. I've always found success in full step changes in the needles, and haven't reaaly felt the need for 1/2 steps.