1980 kz550 TK22 carbs with podfilters figured out

Hey all. Just want to thank everyone who posted before me because I have found your information to be extremely helpful and without it would make this task extremely painful. So thank you for posting all of your experience to share with us.

On with it.
I started with a 1980 kz550 c with TK22 carbs that I fitted with pod filters and has stock exhaust. All of the extra vacuum system and air box was scratched.
Main jet: 100
Idle/pilot jet: 37 drilled by hand with a #79 bit
Needle: shimmed w/ .78mm washer and .034 welding wire

I did pretty much everything one step at a time starting with the main, the needle shim, and then the drilling of the pilot. Right after the pod filters we’re installed, the plugs went from showing very rich to very lean. At this point it got up and went surprisingly quick, but I had no power past 5k rpm. I installed the 100 mains and the top end came alive, I was still noticing sputtering and light backfires as I cruised st 1/8-1/4 throttle. It still felt lean at he lower end and the plugs also showed it. Next I shimmed the needle, which I am not sure that I noticed much of a gain. Right up until before the drilling of the pilots did the bike rev cleanly from idle. By this I mean that when I would snap the throttle as quick as I could it would usually sputter out before reaching high rpms, I would have to roll onto it a bit slower. After I drilled the pilots I am now able to snap the throttle as quick as I want after it’s warmed up. Speaking of warming up, do I even have a kz550 anymore????? The choke time took a huge dive, this thing is ready to ride in minutes.
As I sit here drinking a victory beer I realize that I do have more tuning to do. I get to play with my newly revealed air screws a little bit, my plugs were 1/8” thick, so mark you’re drill bits before you go Messin up your air screw head. Mine were all fine and actually came out on the drill bit, no screw needed.

Fun fact for anyone still reading. I had noticed that not all of the plugs were reading exactly the same color and I did notice that when I was drilling the pilots, the 2 jets that were in the richer of cylinders had larger orifices. I could tell by the feel of the drill bit that 2 of the jets were def smaller than the others from factory. So in the days to come I will be playing with the air screw mixture on the carbs to see if I can get each cylinder looking closer to identical. The screws that were on the carbs with (what I perceive)the dif size pilots were also set at different turns out than the others by at least a half turn.

I hope this can help someone as people in this forum have helped me. TK22 website and loudhvx get a big thank you, I think I’ve read just about everyone one of your posts and allowed me to make tactical decisions and have all worked out. Cheers to you.

I do have few ?s

How should my power be in 5th around 65, snappy? Even when accelerating should I be able to buzz from 55-95 fairly quick or doesn’t it start to slow down? I understand this isn’t a rocket which I’ve had in the past. It redlines really quick from 1st - 3rd or 4th, like fast.
Any pro tips on fine tuning the air screw? Might get those cool little thumb air screws:)

I’m sure I’ll have some questions in the coming days.

That's great to hear! Sounds like you're making good progress.

It's hard to give a good answer on how snappy the power should be in 5th at 65 MPH since it's all relative. Compared to a modern 600 sport bike, it's going to feel slow. Compared to a dirt bike, it's going to feel fast. But I can say the standard Kz550 motor was more of a grunty low-end puller, compared to a Gpz, which was a lot more high-strung. The standard (same motor as the Ltd) is better in tight areas like city streets, especially if you have a passenger.

Setting the airscrews can be done pretty well with the lean-drop method. To do it properly you really need a very precise tach.T he bike's tach is not precise enough to do it. I use an external Actron tach. You need to see very subtle changes in RPM that you might not be able to hear.

With the lean- drop method, you ride the bike until it is good and warm, then let it idle on the center stand. Turn the screws in til the RPMs drop. The mixture is then richer than it should be. Then you slowly turn the screw outward watching the RPMs rise as you lean out, then eventually the RPMs will start to drop again. That's the lean-drop. Then you return the screw back rich to where the RPMs recover to where they were at the highest.

We use the lean drop method, rather than the rich drop, because with a rich-drop the intake tract starts to accumulate fuel. This makes the mixture unpredictable. With lean drop, the intake tract is basically dry when you set the final mix.

Now setting it this way means you might be setting it when the motor is superhot. This is fine if you only ride on super hot days. But it might be a bit lean on cooler days. But since you now have a setting to work from, you note how many turns out the screws are. If you think it's too lean for colder days, you can turn them all in a 1/4 or 1/2 turn and can put them back if it doesn't work out.

If the idle gets too high, you have to reset the idle speed lower and basically start again. (Carb tuning is often a recursive process... where one adjustment is affected by another so you have to go back to the first adjustment to compensate.)

Before I had a wideband AFR gauge, or even a gas analyzer, this was how I set mixtures. Later, using a gas analyzer, it turned out the setting was pretty much right where it needed to be.

Many factors can upset the method, though. The carbs need to be synced. The fuel levels must be right on. The ignition must be perfect and stable at idle. And of course the valves must be set right and compression must be the same across all four cylinders.