I have a 2007 Yz250F. I just recently rebuilt my motor and it runs fantastic. Not too rich or lean, thats all dialed in. It starts in 1-3 kicks every time. However, it only starts that easily when I shut down the motor appropriately (i.e. hit the red OFF button). Even cold, the motor will start that easy if I shut it down correctly. However, there is one big problem I am having. It is an absolute PITA to start if it has been stalled. After a couple laps around the track I stalled it in second gear in a tight corner. I kicked and kicked, and eventually had to pull it off the track. I tried to start it intermittently for about 10 minutes, catching my breath in between kicking intervals. After that, it finally started back up with 5 hard kicks in very quick succession. This whole ordeal actually happened twice, because to be honest I'm not a very good rider so I ended up stallling it twice in the same corner on different laps.
I really don't think flooding is the issue, because I am aware of how much kicking is too much, and know when to give it a break. It also leaks gas when it is flooded, and it wasn't doing that. And yes, I was trying out the hotstart, which didnt help one bit. And since it starts so easily otherwise, I really have no idea what it could be. I do have a hunch though. My motor is a race built monster, and in general, there is not much left on the bike itself that is stock. Stage 1 hotcams, 13.5 comp wiseco piston, full titanium 4.1 exhaust with powerbomb, pro-x steel valves (with tougher springs) on a rebuilt head, along with many, many other things that dont affect HP performance, like boyesen supercooler, aftermarket radiator, hinson clutch, etc etc. It flies when you really want it to. I am also running 100 octane AVGAS, and it seems to be working really well.
Now, I do know that the more powerful you make a motor, the more tempermental and harder to start it will become..right? So can the fact that the motor is so full of aftermarket parts cause it to be such a PITA to start after it has been stalled? Is there anything I can do to fix it...besides not stalling? The only thing I didnt try was the choke, but it wouldnt make any sense to put the choke on to start an already hot motor.
