Kawasaki kz 750 L4 1984 wont go on higher revs or under load.

Calling from Sweden.Hello out there, I just picked up a Kawasaki Z 750 - 1984. Model called L4, I have problems to get the bike to run well at acceleration, Its has been garaged for about 8 years, First thing to do was to send away the carbs to a Ultrasound cleaning, then all jets was careful blown out with compressed air. After reassemble the carbs I changed the plugs,plugwires and caps,cleaned the tank with a new external fuel filter,new fuelline and vaccum line,it starts easy and revs good in neutral,but it will not rev out under load, I also sprayed starting gas at the intake rubbers but it don’t rev up so I dont think there is a airleak,Airfilter is also renewed in factory airbox,. Did a compression test and it shows 120-140 psi on all four cylinders.Please adwise. Sorry about my terrible English writing.

I believe that model bike has the spark advance built into the ignitor. It almost sounds like the advance is not working properly. Maybe it's possible to check using a timing light? If the timing is correct the next thing I'd suspect is the carbs. Actually, that's the first thing but you say they were cleaned. I wish I had a nickle for each time I've read that posted by guys that still have dirty carbs. ..:side:

+1 for Nessism's advice.
Check the fuel level in the carbs with the clear tube method as it could be fuel starvation. Adding an inline fuel filter sometimes starves the carbs to.

Brgds Anders

Most inline fuel filters are directional, ensure you have the flow direction correct. If it isn't you will struggle to supply sufficient fuel to the carbs as previously noted.

Also, if the fuel filter has a paper element and it was designed for a pressurized system (with a fuel pump) it can cause fuel starvation. Be sure the filter is for a gravity feed system.

I would make sure the battery is good. you never know sometimes. charge it with a good motorcycle smart charger, then check it & do a load test. After charging, it should be at least 12.6 VDC but a good battery will be higher. One time my motorcycle started running poorly at speed, then would quit. so I limped home at slow speeds & found that the electrolyte was low. I had a similar problem some time later from a bad battery >> after charging then doing a headlight high beam load test, the voltage dropped well below 12.0 VDC. Also but not as severe, the motorcycle had a high speed miss >> the coils were bad, getting very hot.

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