Motorcycle Repair: 1971 Kawasaki f7 wont idle, air screw, vacuum line

Question
Chris, I have gotten my F7 to run, but not properly. I have the manual and have done all of the set up (float height, air screw, cable setup etc.) and have also eliminated the following either by testing or replacement. The rectifier, coil, new battery, spark plug and carb kit including recently cleaned and passages blown out. I put a new head gasket on and the cylinder looked good. Today, I tried different needle heights to no real effect. The problem is I can get the bike to start and run with the choke on, or once it's running, I can keep it going by keeping the rpms up, but it begins to bog with throttle around idle speed, then stalls. Even at higher rpms, it seems to lack power. Please help me figure out where to go from here.
Thanks

Answer
Hi Richard.

Sometimes the simplest things are the ones that we miss.  Happens to everyone, without exception.

Did you synchronise the carbs?

Have you checked the plugs after running the bike to see if it is running rich, good or lean?

Has the bike been in storage for years before this?  If so, then the problem could also be varnish in the tank, if you did not reseal the tank.
 If this is the case, then the carbs will need to be recleaned and the fuel line replaced.

One last thing to check.  The vacuum line for the fuel valve and the fuel valve itself.  Rebuild the fuel valve and replace that line.  They could be part, or even all of the problem.

Let me know what you find.
Good luck and ride safe.
FALCON