1994 CBR 600 F2 Carb Issue? Or what!
 

I just got my second CBR 600 f2 and this bike is in ruff shape but for $400 bucks who can complain? Now the issue Im having with it is, It will not go over 7k RPM in 6th gear. 1-5th Its fine, bounces off the rev limiter but as soon as you gear up into 6th it just bogs down and I have to feather it to a sweet spot which is right between 6.5-7k RPM and wont go over that. The previous owner told me the carbs just need to be synched, But before I go out and buy myself a $100 tool and it might be something even simpler what should I do guys. I just spent my whole pay check on the bike, and everything I could think of to make it look pretty off ebay (Will Post Pics Before and After) But I have to get it running right. Any input at all would help!!! Thanks In Advanced. Also it is Naked if that matters I was reading something about the air intake.

The air intake when naked usually only happens at cruising. You can make a carb sync tool pretty cheap. Theres threads somewhere around here. How long was it sitting? What was the gas like? Any intake leaks that you know of? I'd check the fuel delivery first, then clean the carbs real good, just to ensure its done, then sync them and gofrom there. others will chime in with their suggestions. The best route is start simple first. Do the free things and checking, then spend money. I learned that the hard way along time ago ha.

I coudlnt wait anymore, I tore the bike down changed the plugs cleaned the carbs and bench synched them. The carbs looked brand new inside, I held the diaphragms up to the light no holes, the slides are all working properly I used a piece of string and cleaned the jets out. there wasn't anything in them these carbs where just professionally cleaned. I put it all back together, it fired right up I took it down the street and again it ran amazing in 1-4 but 5th it bogged down and 6th it bogged down I checked all the lines Ive already ran two full tanks of gas through it so water in the tank isn't an option. WHAT ELSE COULD IT BE??? Also The air filter was a little dirty but not enough to cause any lagg. (K&N)

Weird. Make sure none of your carb vent lines are bent, and they are all connected. A homemade sync gauge is easy to do. Just google it. Maybe change the filter and try removing your fuel cap to ensure its not a vacuum lock.

It's weird that its only in 5th-6th. Engine doesn't know what gear you are in. Is the airbox hacked? Maybe some ram air mod that is killing you at higher speed.

Air box is stock with K&N filter and the high speed thing makes no sense cause I can do 100 MPH+ in 4th gear but as soon as I shift up it just drops lol Ive talked to mechanics and I get a different answer EVERYTIME. Ive never had a bike do this I had them start out sluggish but never the other way around.

K&N filters can cause turbulence around the main jet at high speed, it says this in the K&N/dynojet jet kit instructions, but I still run one.

The thing is it will run fine in 4th gear and Im around 10k rpm doing 90-100 but as soon as I shift up it just wants to die tomorrow I am going to strap a camera to my chest and take it for a ride so you can see first hand what its doing...

Yeah shifting gears will change the rpm and put it in that "flat spot". On another note, is your petcock working correctly? as in not leaking and has no tears in the diaphragm etc. etc.

I will pull the petcock off tomorrow to check that everything is sound I was just reading another post and someone said there kick stand sensor made there bike do the same thing lol and I read that a solenoid could do it as well.