POOR PERFORMANCE

Howardb, thats great information. So as i read it im assuming that i cut any wires at the rear of the speedo other than the one going to the light bulbs to eliminate the speed governor. Am i on the right path or is there more to it? I do know there is not anything additional at the gear drive at the wheel so the limiter must be at the speedo itself. 
If im off track can someone explain how to remove the limiter circuit?

EDIT.. Google is saying there is not a speed limiter on this bike...  what to believe is confusing.

Do you have a service manual with a wiring diagram?
I would trace any wiring that links the speedomter to the ignition module (referred as the I.C. Ignitor)
Without having ever seen such a mechanism, it is unclear if simply cutting the wiring would eliminate the limiter. Possibly, in addition to cutting the connection from the speedometer it might require grounding that connection at the igniter, or even tying it to +12v through a 250ohm resistor. Either way, proceed with caution, hence the current limiting resistor!

I am curious about the source of the information concerning the governor. I do not remember ever hearing of such a law, and I wonder why it would not also apply to the liter bikes.

I've just searched chatgpt again and it is lying!  In my previous post I copy/pasted directly what it returned in my search for "performance issues Kawasaki 1983 KZ750 L3" .
Now it says that a limiter was NOT fitted, but disabling such devices is ILLEGAL
Grrrrrrrrrr.

So lets go with no limiter for now. So parts fiche shows front as a 13T sprocket and rear as a 33T. So if the ones on mine are correct and no limiter then what to check??  Im gonna look up what size the main jets are supposed to be also. My planned checks are diaphragms for pinholes, compression check, colortune to see burn condition, any impingement to throttle shaft, lube advance governor and put timing light on it. Anything else you guys can think of??
 

Still sounds like a lack of air/fuel or a restriction in the exhaust - how are you planning to look at a colour tune doing 80mph (carefully I hope) might be safer to pay for a run on a dyno where you can see an AFR reading 

Ill have to order some exhaust gaskets before i drop the pipes. I can borrow a snake and run it through them. Im not inclined to think its that but its just a few hrs to take them off and snake them just see. I will try sticking some coat hanger wire up from the tail end first and if that wont feed up to the header pipes ill borrow the snake.

That may not be possible. The couple of factory mufflers I have seen the insides of (they were not from a 750) had baffles that would prevent any sort of snake. 

Was over at kawasaki looking at fiche and it looks like i may be able to take mufflers off the headers. Ill investigate that angle too. 

The pertinent question is "does the lack of performance become increasingly evident as you go up through the gears?" 
If it does then it could be caused by any number of things.
If it doesn't and is only evident in 5th then that rules out things like exhaust blockages, fuel/air mixture, throttle linkages etc. 
A combustion chamber doesn't know what gear it is in and produces  the same volume of exhaust gases at 8000 rpm in 1st gear as it does at 8000 rpm in 5th.
A throttle linkage operates the same in 1st gear as it does in 5th.
Anything power output related (fuel/air mixture, compression etc) will be evident in all the gears but becoming increasingly evident in the higher gears in a linear fashion as the drive load increases. 
If it were some kind of speed related limiter causing the issue which was set at, say, 70mph you should be able to trigger it in 3rd, 4th and 5th.
If it were some kind of revs related limiter you should be able to trigger it in every gear. 
On both types of limiter in whichever gear the motor would behave normally until you reached the limiter in every gear. 

The only way that makes any sense for it to perform well in in all four lower gears and then fall off a cliff in top gear is specific top gear ratio. 
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Warren3200gt wrote:

The pertinent question is "does the lack of performance become increasingly evident as you go up through the gears?" 
If it does then it could be caused by any number of things.
If it doesn't and is only evident in 5th then that rules out things like exhaust blockages, fuel/air mixture, throttle linkages etc. 
A combustion chamber doesn't know what gear it is in and produces  the same volume of exhaust gases at 8000 rpm in 1st gear as it does at 8000 rpm in 5th.
A throttle linkage operates the same in 1st gear as it does in 5th.
Anything power output related (fuel/air mixture, compression etc) will be evident in all the gears but becoming increasingly evident in the higher gears in a linear fashion as the drive load increases. 
If it were some kind of speed related limiter causing the issue which was set at, say, 70mph you should be able to trigger it in 3rd, 4th and 5th.
If it were some kind of revs related limiter you should be able to trigger it in every gear. 
On both types of limiter in whichever gear the motor would behave normally until you reached the limiter in every gear. 

The only way that makes any sense for it to perform well in in all four lower gears and then fall off a cliff in top gear is specific top gear ratio. 
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Don't disagree with any of the above but you are on factory gearing so the issue is bizarre. Normally a lack of "torque" will stop a vehicle pulling in higher gears but this would be apparent to a lesser degree in other gears also. Below is a chart showing what you should be able to achieve in each gear, might be worth going for a ride and see how your bike compares in each gear ?

Guys, i can race it like im going down a dragstrip through all 4 gears then it hits the wall in 5th. I dont think i hit redline but i do recall seeing 8000 plus on the tach. Buddy and i went for a ride just before i initiated the thread and we decided to race it like at a track. We found a back road and i went for it. This is how i know its ( from what im experiencing anyway )  a 5th gear issue. I can do it again and record speeds and revs at some point. Only gonna be 30 today so it wont be today.
I can confidently say it will do redline in first 4 gears if i held throttle till it did.. im sure of that. First thing is im gonna count teeth and see if they are both stock sprockets.