Hello all, I just bought a 2006 cbr600f4i a few weeks ago and it was running great, but now I have an issue with bogging and hesitation past 3k rpms at hot engine temps.

When the bike is cold it runs like a champ and even up to 200 degrees but when it gets hotter like at red lights or slower traffic speeds at 200 to 220 I get hesitation and stuttering like its being starved for fuel. it will Idle just fine and i can take off in first but anything past 3 to 4k rpms it wants to die. I pull over and turn it off for a few minutes and then it runs fine for a bit, but then it comes back.

I did some testing of the charging system and checked the plugs

The fuel pressure regulator wasn't leaking any gas from the vacuum line.

The spark plugs look good and not fowled, and the coils aren't cracked and look good
I did buy some new plugs just in case.
I also put a glove on and checked the headers they are all extremely hot.

The battery tested good
with the bike off it sits at ~12.5v-12.9v I checked it a few times cold and after a ride.
at idle hot temp its at 12.7v-12.9v
at idle with cold temp it sits at 13.3v-13.5v

at 5k hot low beams is 13.3v
at 5k hot high beams was 13.6v
which seemed weird would think it would be other way around

The stator tested good
.3 ohms between all phases
18-20VAC at idle all phases
~50VAC 5k rpms all phases

the regulator diodes checked out okay
charging seems a little low though but it's my first inline 4. regulator looks like it was replaced at some point the stator plug looked newer than the plug on the stator, but it still looks older

Would a fuel pump cause this when it gets hot? any ideas would help thanks in advance.

 

Same model and year bike, mine does something similar. Doesn’t always happen at high temps and most times it happens in the higher rpm but it does vary and sometimes will be at much lower rpms and also happens in any gear. If you figure anything out please lmk.

 

So i just worked on it today

I started with the kill switch and cleaned the contacts inside
I also cleaned the plugs for the stator and the rectifier and the ecm, really any plug I could get to with contact cleaner
cleaned the ground to the frame/engine and the battery terminals

Previous owner put CR8E plugs in it so I switched them back to imr9's

Rode it around for an hour and a half or so in 90 degrees in traffic and had no issues
couldn't tell you which one helped but my charging to the battery is now 12.9-13 at idle and almost 14v at 5k rpms
Something like a bad connection was causing low voltage and bad spark I believe

So If you know fuel/air mixture isn't an issue you could try the stuff I did.

 

Great result, more often than not this type of issue is getting more common as the bikes age, esp when Mr Honda neglecting to use waterproof connectors.