I have a 1993 cbr1000f that I bought about a year ago. It was a project bike for me. I had to strip the bike down to the bare frame and then put it all back together. Now she won't start. I put in new plug becuase the plugs were getting old. I checked to make sure i'm getting a spark, and I am. I'm getting gas to the cylinders. I took the carbs off and cleaned them. Right now I have the headers and air box off. The only thing I can think of would be that I'm not getting enough back pressure by having the headers off. But I feel like the bike should still fire up but not run 100%. It is turning over like it should but for some reason it just won't fire. I also have 87 octane gas rather than 93 octane. All I had in the garage was 87 octane.
Please help me figure this out! I want to ride soo badly!

Thanks for the help.

 

Check the basics
1 Charge the battery[ these bikes don't like a half charged battery.
2 Check your kill switch isn't corroded
3 Check your sidestand switch
4 Check all the fuses, incl the main fuse 30 A
5 Check the choke is operating correctly.
6 Check the carb boots for tears or holes.
If all of those are OK and you have spark and gas (no matter what octane) she should fire. (Make a helluva noise without headers)
Unless the valve timing is so far out that she backfires.....
Let us know.....................

 

I finally got her running. It ended up being that the pressure on the carbs was equal. I got it to fire by covering up the back to the carbs with both my hands while a friend tried starting it. So I threw on the air box and exhaust and she started right up.

 

Excellent !

Covering the air intakes like that means you were choking her manually - maybe check choke cable for future reference......