I'm going to be as descriptive as possible. I have a 91 cbr 600 f2 which I recently purchased as a fixer upper. Two things I have noticed about the bike. The bike runs rough until I reach high rpm around 5 or 6k then it takes off. It sounds like it's not running on all cylinders(did research on real sound) and by far it sounds like it is running on 3 cylinders. What I dont understand is the popping sound that comes out of the exhaust. When at idle is the worst especially at a stop light. The motor is at idle and i'll hear pop, 4 seconds later... pop. It just pops all the time. The exhaust kinda smells like gas and when it pops it pushes alot more exhaust out with a little blue flame. Anyone have an idea on what these two symptoms sound like??? PLEASE

 

Sounds like a fouled plug to me.

 

Change your plugs. Clean your carbs. It would probably be good to change the brake fluid, oil, flush your cooling system, check your valve clearances. After all those things the bike should run like a top.

 

And completely clean and sync your carbs (not just a half assed quickie clean)

 

Carburators can be easy to screw up. You can take them to a shop off the bike and have them cleaned. You need to record the settings of the jets and mixture screws so you can put them back right. If you want to clean them yourself there are many tutorials out there. Also, at harbor freight they have a ultrasonic cleaning machine, which shops use to clean parts. It vibrates the water and does a very good job with things. You may want to look into that if you do it yourself.

Turn in all mixture screws and jets and record how many turns it took to bottom them out, before you remove them. DO NOT over tighten them. Carb parts are brass and they will easily strip or get messed up from a screwdriver that is not the right size. Make sure you have a screwdriver that bridges both gaps of the jets to remove them. Sometimes it can take some force and putting force on a screwdriver that doesn't fit correctly will damage the part.

There is much much more to cleaning carbs. Search for a tutorial and read allot before you start.