Engine loses power or breaks up above 5500 rpm. Runs great otherwise.

Hi
I have noted that after rebuilding my head and installing new piston rings that my engine does not like going over 5500 rpm. I loses power and starts to break up. I have new plugs valves are adjusted carbs are clean but only bench synced but I never had any problems with that before. I did have a issue with gas flow when the tank is 100% full. I took the cap apart and cleaned it but it was vary clean and did not solve the problem. I took the petcocks out and they were clean. I don't know why it is not flowing at full stream. Otherwise the bike runs perfect. Starts right up runs on all 4 has plenty of toque and power up to 5500 rpm dose not skip or run hot. What do you think it could be ?

 

Carbs are clean, but are the fuel levels correct?

The XJ1100 has a vacuum ignition advance. Is the vacuum line in good condition (holding vacuum). Petcock vacuum line should be checked as well.

 

^^+1 agree with k-moe your float level is possibly wrong..if it is to low it will be starving for fuel at higher rpm ( may run great other wise) You may need to wet set float level.

 

I did set them wet a few years back. Never changed them. The only thing different now is I took off the petcock vac thing and I ran the lines like this ...rear petcocks go to the carbs and the fr0nt are connected to each other or the same a blocked off. The bike sat for a longtime in a wet shed before I got around to fixing the bent valves and the Vac advance might be bad. The turn canceler stopped working in the time. The gas cap is also suspect but I will check the level on the floats next time I am in the mood to work on it. I don't need to go over 5k for the type of ridding I do but I want it working 100%. I am going for a ride today

 

Hey Jetfixer Are the guy that got your bike stolen and then rebuilt it?