It sounds like the carb cannot pull fuel up through the main jet, or else the pilot jet is clogged. If the bike starts when you dump gas into the carb, then you have spark. If you have spark, and air, then the other variable is fuel. The Mikuni is a simple, simple carb to work on. Pull it off the bike, open up the float bowl.
Remove the main jet and the little brass hat, then push the needle jet upwards through the carbueartor and out the top. Clean it good.
Remove the float and the needle. Clean it out thoroughly. That leaves the choke circuit and the pilot jet. The pilot jet is small but needs to be clear, and the best way to ckear it out is with a small steel guitar string. If you don't have a guitar, head off to the music store and buy some strings for $5. You can then use the string to push through the clogged pilot jet. As for the enrichment circuit lever (choke), when you push down the lever, it pulls up on the enrichment circuit. If it's stuck, you'll need to disassemble and free it up. If there's any varnish in the passages, you need to clean it out. I use Cyclo carbuerator spray for most of this work, along with latex gloves. Once the carb is clean, it should be able to deliver the appropriate fuel when you kick start it and it should stay running. Something is clogged in there right now.
Dan from haslett, September 2008
