I'm diagnosing a non-starting 03 600RR.

1.Why arethere two injectors per cylinder, one set that fires directly into the intake and one setthat firesinto the throttle bodies from the top of the airbox?

2. Do both sets fire at the same time, or does one set turn on at a particular rpm/load?

3. If I am trying to start the bike, should the injectors on the top of the airbox be firing?

I searched but did not find the answer to this question. I have the shop manual for the bike and have a lot of mechanical knowledge, but little knowledge of fuel injection systems. If you want more details about the bike, let me know. Thanks,
Justin

I should have read the manual more closely. The injectors on the top of the airbox are referred to as secondary injectors. The injectors below the throttle bodies areprimary injectors. The secondary injectors only come on when engine speed is above 5500rpm or throttle opening is over 50 degrees.