I recently purchased a non running 05 or 06 zx50. After getting it running, I replaced the exhaust with a new stock unit because the previous owner had gutted the back end of the muffler which made the bike unpleasantly loud! The air filter assembly was also missing so I purchased all new stuff for that too. When I installed the new filter assembly the bike would not run. It would start but would not rev above idle. I got it to run by lowering the float level and removing the air adjustment screw. Now it runs fine as long as I keep the speed at 30mph. If I try to run 35Mph it will do so for about 1/4 mile and then start to sputter and eventually die. If I put my finger over the hole where the air screw goes it will start right up and I'm on my way. If I don't cover the hole for the air screw it won't start. Does anyone have any ideas? I was wondering if a smaller main jet would help.
