Hello all! I am new to the forums and have a serious question to ask. I just bought a 99 CBR 600 F4 from a guy that I know. He had the bike sitting in his garage for a while and he did not ride it hardly at all. He owned it for about 1 yr and let it sit most of the time and rode his GSX 750 most of the time. I went to test ride it and noticed that it rode kind of rough in 4-6th gear at around 5-6k RPMs. This was after the he had changed the oil and plugs. I decided to go ahead and take a chance on it hoping it was just some gummed up carbs or something. I took the bike to my local Honda dealership and they cleaned the carbs, changed the oil again (which they said looked real bad) and put new plugs in it. Now I know the guy i bought it from changed the plugs and the oil and i don't think the dealership was pulling my leg on the fact that they did it too. I got on the bike and rode it home and it ran great. Bottom end was running better, mid range and top end were good with smooth acceleration. I stopped by my house and later went for a ride and the problem started again, running rough at around 5-6k rpms in the higher gears. It doesnt necessarily feel sluggish as it feels like it is flooding out. If I open the throttle, it just chokes it. If I slowly accelrate through, its ok. If I gear down to get it up to 6k or better, shes off like a rocket.

Has anyone had the same or similar trouble with their bike? If so, what was the cause? I am worried its going to be costly or too serious to bother with. I bought this bike to fix it up and ride for a while and it is just killing me because I love this bike, but it looks like its going to take me for a ride.

 

Sounds like the jets are still gummed up. May want to clean them yourself to make sure they really are clean.

 

Did you check the air filter?

 

It has a new air filter too.

 

Def sounds like a carb problem. I would take it right back to the dealer and bitch. How much did you just pay for them to fix the problem? I work for a car dealership. Trust me, take it back and bitch. If you dont get anywhere ask for the service manager. How many miles?

 

mine does that same thing sometimes but only when its cold, after the engine warms up it doesnt happen any more. i have a 2000 cbr600f4. now thinking about it ,last year i switched to amsoil synthetic which cost a little less than honda oil and it seems to be running better ,but mine was doing it in 1st & 2nd

 

what type of gas are you running? I have heard that some octanes/brands/ethonols can cause issues. Just a thought, good luck. And how much did the dealership charge you out of curiousity

 

Sorry for the delay in a response....I have run different octanes in gas, so that is not it. I had an "exchange" with the dealership and got nowhere since they said all i told them was to clean the carbs (I told them I thought it was the carbs), so no money back there, that was $400 for the carb clean, oil and filter change, and new plugs.

I have had some friends tell me that there is some kind of "switch" in the upper gears that controls how it burns the fuel around that RPM range and that it could be hanging up or not switching right. Anyone ever hear of that?

I have a friend whose dad is a good mechanic and he is going to take a look at it for me at no charge so we can figure out what is going on. Wish me luck! I just want it to ride good so I can enjoy it even more.