wrong float level= to rich?

hello, i have a 79 kz750 twin. i got it about 3 weeks ago. when i got it rode great! since then its been going down hill. not sure why. some stuff that has happened since i got the bike.

4" hole in exhaust. welded up
put seam foam through bike. all gone now.
cleaned the float bowls and jets ect.
according to the previous owner the carbs were rebuilt 2 years ago and i do believe him because all the jets ect looked amazing.
floats arnt sticking either.

so since then ive been trying to get it to run right.

it idles fine. but when i give it gas and go to take off it sputters.
and the plugs r super black and sooty.
my question is can floats set to high cause this problem? or possilby bad spark? im running hotter plugs. ngk's . like i said when i got the bike it ran amazing.ive tried adjusting the floats but just havent gotten it right yet. also tried the turning the pilot screws but no luck. thanks for the help.

also i will be adjusting the floats with the carbs still in the bike. with that being said if i bend the tang up towards the cabrs that will make it leaner correct?

newowner79kz750b1 wrote: hello, i have a 79 kz750 twin. i got it about 3 weeks ago. when i got it rode great! since then its been going down hill. not sure why. some stuff that has happened since i got the bike.

4" hole in exhaust. welded up
put seam foam through bike. all gone now.
cleaned the float bowls and jets ect.
according to the previous owner the carbs were rebuilt 2 years ago and i do believe him because all the jets ect looked amazing.
floats arnt sticking either.

so since then ive been trying to get it to run right.

it idles fine. but when i give it gas and go to take off it sputters.
and the plugs r super black and sooty.
my question is can floats set to high cause this problem? or possilby bad spark? im running hotter plugs. ngk's . like i said when i got the bike it ran amazing.ive tried adjusting the floats but just havent gotten it right yet. also tried the turning the pilot screws but no luck. thanks for the help.

also i will be adjusting the floats with the carbs still in the bike. with that being said if i bend the tang up towards the cabrs that will make it leaner correct?

No. You don't use bend carb float tangs to adjust fuel mixture, and if the bike was running great initially why would you suspect the fuel mixture suddenly needed adjustment? I suspect you have un-adjusted things to a point that is making the problem worse. If the bike was running great 3 weeks ago there's about 1 chance in a million the carbs floats needed to be touched. If so far the only thing you have done is made changes to the carbs, I respectfully suggest you take the bike to a knowledgeable motorcycle mechanic who regularly works on old KZs and have him adjust things back to normal. No offense intended, but to just start turning pilot screws, bending float tangs, changing spark plug types, etc. without first diagnosing the problem will definitely create problems rather that cure them. Ed

when i got the bike home i let it sit for 3 days. the po told me that sometimes the float sticks. so indeed they did stick. so i took both float bowls off and saw that each float was set to a different height. from everything that ive read they need to be within spec and close to the same height which they were no where near the same height. that is why i adjusted the float. also when i brought the bike home it would only run with the choke half way open. so far ive ive got the bike to idle without the choke at all. so no offense but im going in the right direction. all i need is a little guidance. i live in a small town so im having trouble finding some one to work on old bikes especially carbs in general

No offense taken.

You state you are trying to set float height with the carbs on the bike, but this isn't going to buy you much. If you have already bent the float tangs or if they were already monkeyed with by the previous owner what needs to be done (or re-done) is to accurately set the fuel level in the carbs. This can only be done using the clear tube method. Bending the tangs with the carbs on the bike is not an accurate way of adjusting the fuel level.

You stated that when you got the bike 3 weeks ago "when i got it rode great!" and "... like i said when i got the bike it ran amazing." But elsewhere you state "when i brought the bike home it would only run with the choke half way open." Since the bike would only run with the choke half way open and the PO said the floats stick I believe the carbs need to be properly cleaned regardless of how spotless the jets look (2 years the same as 100 years if fuel sat in passageways and tiny orifices during that time). When you say you went to a hotter plug type; specifically what plugs did you use?

Here's my guidance: 1. Get a Kawasaki service manual. Every owner, no matter how much or how little experience they have should have one when working on these bikes. Among other things, it helps you diagnose problems and make accurate adjustments. 2. Clean the carbs properly and set the pilot screws, fuel level, and any other adjustments to the specs in the manual. 3. When that's complete see how the bike runs. If it's still not right, and if you're positive the carbs are perfectly clean and adjusted, check other tuning parameters on the bike (such as ignition, valve clearances, etc.) to ensure they are in spec according to the manual. Ed

will do ed. thanks alot! yea it ran great even though the choke was half way. i no its not the way it should be but did run amazing. which means to me that it was actually running lean since the choke had to be on. i deff will do the wet method with the clear tube as set everything to spec to the best of my abilities. all im really trying to do is get it so that it runs good enough so that i can ride it before the summer is up. then ill take the carbs off and all that fun stuff. im a new rider and just got my permit and bike like a month ago so i havent really even be able to ride it. the plugs b8es

Ok. Am I correct in understanding you have a 1979 KZ750-B4? If so, the spark plugs you're using (B8ES) may be too cold for your bike. Take a look at the rough specs for different KZ750 twins in the link below. Notice that although the 1976 KZ750-B1 calls for the B8ES plugs the 1979 KZ750-B4 calls for the B6ES. This plug is 2 heat ranges hotter than the B8ES. I cannot vouch for the accuracy of the information in the link, so I suggest you double check if you have the owner’s manual or maybe someone on this site can verify which plug should be used. There's a pretty big difference between the B8ES and B6ES plugs, so check before switching. Ed

www.cyclechaos.com/wiki/Kawasaki_KZ750B

u my friend a correct! but i have a kz750 b4, but b6es plugs r still correct! i just looked at my manual and it is b6es! my local oreilly carries motorcycle parts and they looked in their book and said it b8es which i bought the bike and changed the plugs they said b6es and i questioned them and they told me i was wrong. which im no mechanic so i believed them! do u think the plugs could be my problem with the bike running to rich and me thinking its the floats?

when i first the got the bike the right side carbs float was set richer then the left side. i no have the floats set how i got the bike but with the b8es plugs in.so maybe if i get the right plugs it might run again?

Sorry about the typos - I meant to type KZ750; I have corrected it. Anyway, I would give the B6ES plugs a try if your manual calls for them. They should not soot up as bad as the B8ES. If you find they burn too hot you can try the B7ES plugs. The dealer may have looked up the KZ750-B1 specs when giving you advice. Just a note, on my bike (which really is a KZ650) the original shop manual called for B8ES and my plugs always had a little soot on them. The next revision of the same manual for my bike called for B7ES plugs. I switched and the soot problem improved big time. I have no evidence, but I suspect when the factory first tested these engines they ran the living daylights out of them so they found the colder plugs worked well; but then after thousands of bikes were on the street they discovered hotter plugs worked better under normal operating conditions. Ed

that makes perfect sense. i really appreciate all your help ed! i went and bought some b6es plugs today and in the next few days im gunna tinker with the bike again change the plugs first and see what happens and then check the floats again. ill keep u informed.
thanks again
Blake

Just my two cents. I would stop thinking of the floats as needing to be level with one another. The floats close the needle that I'm sure you understand. Keep in mind the floats may NOT be exactly the same size therefore would not require the same level. That is why the manual tells us to use a fuel level have, part # 57001-208 to set the floats. It can be a bit of a chore to do it this way but is by far the best method. For around $50 I believe there is a bench tool that will set them dry but I have no idea how reliable it is. One newbie to another.
Good luck,
Jon