Motorcycle Repair: Kawasaki Ninja 1992 ZX7, kawasaki ninja, wiring circuits

Question
I park my bike in an underground garage, I took it in for a tune up/oil change. I found that the previous owner had removed the air filter, perhaps due to the aftermarket pipe. They did a tune up and replaced the air filter. Anyways when I received my bike back I have had nothing but problems. I took it back they relined the gas tank, rebuilt the carb. I am still having problems, Sometimes it starts, sometimes not, when it does start it will just shut off after a minute or so. It also backfires somtimes when I try to start it.
This is costing me huge money and the problem isn't being resolved. Any thoughts?

Thanks
Richard

Answer
Hi Richard.
 My thinking on this is that the previous owner may have rejetted the carbs when he installed the exhaust system.  That could be why the air filter was missing.  That harmed the engine, since that filter takes stuff out of the air that can harm the engine internals.  I also think that the synchronization and timing are probably a bit off as well as the valves.  These are all (except for the mixture, which requires some experience to do right) things that you can fix yourself with the tools and instructions listed in the repair manual.

 Check the plugs and I'll bet they will be whitened and/or burned away a bit.  That means that the bike is running lean.

You could also have an intermittent short or bad fuse or connection in the ignition or main wiring circuits or the ignition switch.  The wiring diagram is in the repair manual.

Start with those and let me know what you find.
Good luck.
FALCON