Can't tell if I'm running too rich or too lean

82 KZ750 with 4 Keihin carbs. 4 into 1 exhaust, stock airbox, new intake boots. I just went through them because I was leaking gas out of the carb mouth, cleaned up the needle and seat, made sure the diaphragms looked good, replaced O-rings and gaskets and whatnot. From what I can tell, I'm not leaking gas anymore so mission accomplished, but I still have an issue of several foot long flames coming out of the exhaust. It almost immediately fouls new spark plugs, and I've got the mixture screws out about 5 or 6 turns and it doesn't seem to be making that much of a difference. Which sounds like a super rich condition to me. But if I remove the air filter to cheaply try and get more in the system, it won't even start... which makes me think it's running too lean with everything together. 

youtube.com/shorts/zUMSA6AHF7I                <--   the flames in question

When I had the carbs apart I could tell someone had been in there before, the bigger middle jet says 65 if I'm remembering right. That and the plastic plugs were missing, I put rubber ones in but I'm not sure if I even needed to do that. I'm not really sure where to go from here. I also was having problems with the slides getting stuck up, I cleaned them real well and they seem to be moving fine by hand, can't see if they are moving when it's running

 

The farther open the pilot screws, the richer the mixture.  These are not air bleed screws.

You might want to take inventory of all the jetting and compare against the factory manual.

And yes, you need the pilot plugs.  

Oh thats annoying. Everything I was reading said turning them out leaned the mixture. Guess I'll tighten them up tomorrow. 

I used rubber plugs since the plastic ones were missing, and those seem to be staying in, I hope they aren't leaking still. I'll take the carbs off- again, and check the jets. Are they all going to be marked with sizing? I havent really ever messed with carbs to this level

You may need a magnifing glass to read the jet sizes on the jets. I have had China jets that the # on the jet did not match the actual jet size. If the jets do not look origional, they may be from a cheap China rebuild kit that a P.O. installed.

Walnut wrote:

Oh thats annoying. Everything I was reading said turning them out leaned the mixture. Guess I'll tighten them up tomorrow. 

I used rubber plugs since the plastic ones were missing, and those seem to be staying in, I hope they aren't leaking still. I'll take the carbs off- again, and check the jets. Are they all going to be marked with sizing? I havent really ever messed with carbs to this level

I don't know Kehin carbs at all but Mikuni carbs with air screws....you would be correct.  As they screw out they allow more air, making the pilot mixture leaner.

Pics of the carb front and back would be helpful. Sounds like CV carbs. If so do the thumb test. Raise the slides, put your thumb over the vent at the top/backside of the carbs. They should lower slowly. I not they may be stuck open causing a rich condition. If fast the bike won't run for SHT. 
Steve

1) Get a baffle in the pipe ASAP!  There is nothing worse than an annoying as hell open pipe bike, pissing off everyone within a half mile of your bike.

2) Perform a proper carb rebuild.  This requires unganging the carbs, removing all parts, including pilot screws, pilot jets, bleed pipes, etc, then soaking all these parts in carb dip.  During rebuild, replace all the O-rings, and get new float needles.  OEM or Keyster brand needles are much better than the cheap replicas.

3) Your bike is running pig rich.  Just look at the video showing tons of black smoke, that's an over rich condition.  Check that the choke is opening properly, and verify fuel level using the "clear tube" test, as detailed in the factory Kawasaki service manual.  If you don't have the manual, download it from this site, for free.

Yep gonna have to fix that. This guy doesn’t like competition.

SWest wrote:

Pics of the carb front and back would be helpful. Sounds like CV carbs. If so do the thumb test. Raise the slides, put your thumb over the vent at the top/backside of the carbs. They should lower slowly. I not they may be stuck open causing a rich condition. If fast the bike won't run for SHT. 

I'm not actually sure I know what vent you're referring to. I see the vacuum port but that's it. 

Nessism wrote:

1) Get a baffle in the pipe ASAP!  There is nothing worse than an annoying as hell open pipe bike, pissing off everyone within a half mile of your bike.

2) Perform a proper carb rebuild.  This requires unganging the carbs, removing all parts, including pilot screws, pilot jets, bleed pipes, etc, then soaking all these parts in carb dip.  During rebuild, replace all the O-rings, and get new float needles.  OEM or Keyster brand needles are much better than the cheap replicas.

3) Your bike is running pig rich.  Just look at the video showing tons of black smoke, that's an over rich condition.  Check that the choke is opening properly, and verify fuel level using the "clear tube" test, as detailed in the factory Kawasaki service manual.  If you don't have the manual, download it from this site, for free.

believe me, I'm going to find a baffle. I have to wear ear protection to rev it in the garage. 

I'll try the clear tube method, I've seen a video of it but I haven't looked too much into it. If fuel level is too high do I just bend the float until it isnt? Can I adjust the level from outside the carb?

Are you sure the engine is running on all four cylinders?  You might want to start up the bike from cold, then check the header pipe temperature to see if there are any dead cylinders.

Walnut wrote:

I still have an issue of several foot long flames coming out of the exhaust. It almost immediately fouls new spark plugs
 

In general, neither of these will be caused by a lean condition.

Even if it's burning a LOT of oil and fouling plugs right away, you won't have the flames. Fuel-fouled plugs and oil-fouled plugs will smell very different, so you can let your sniffer be your guide.