So my bike started to run extremely rough around 5,000 RPM. I had this problem before and the bike would eventually starve for fuel then die. I found it was a faulty fuel pump before replaced it and didn't have anymore problems for a summer and a half. About two weeks ago my bike started to cut out around 5,000 RPM it felt the same as the fuel pump problem so I eliminated the fuel pump and ran the fuel line gravity feed. This improved the bike slightly but didn't eliminate the problem. Oh btw the bike has around 8,000 miles on it, no front plastics, k&n air filter, and Jardine pipe. I thought the plugs were going bad so I replaced them and I thought this cured the problem. After putting in new NGK iridium spark plug I gained back a ton of performance and now the bike only hickups a little around 5,000 but if you drop the clutch, roll on to full throttle, or drop a gear, the bike cuts out again. Any ideas on this. I know a lot of people have problems with there R/R and stator and I experienced it with my old 900RR but I don't get why the bike runs great after it gets over the 5,000 rpm hump if it was that. Any idea's would be greatly appreciated. Oh yeah I know I need to jet the bike I'm at 2,300 feet above sea level and not running the factory air ducting, not to mention I was told by Two Brothers that a K&N shouldn't be run with a pipe on the 600F4 because you will actually lose power with out a jet kit but they were on the bike when I got it so I left it. I'm at a loss though because my bike has always run strong.

 

nothing to do with the ducting...I just got back from riding mine no air ducts, no PAIR, no crank case recirculation and it runs like a champ...

I had the carbs split apart to replace all the o-rings between the tee connectors but while in the process I cleaned them and synced them. If you got the plugs and it's not a fuel pump issue I'm going to go out on a limb and say you need to go through your carbs.

 

I've heard that w/o the ram air it will run like crap past 5kish as well... but I've ran mine without ducts as well w/ no issue... just runs a lil rich

 

Yeah I've been running it with out ram air for two years now, it's probably a carb issue which I really hoped wouldn't be the case. Oh well what a great excuse to get the jetting it always needed https://cbrforum.com/forum/images/icons/icon10.gif

 

the jetting will give you a huge power gain, its not much fun to install, especially when the most common answer you will get to your questions is to just try it, change something and try it again.
Took me 2 full days of messing with different settings, learned what changes to make, I ended up with the needle set to clip #5 140 outer jets and 142 inner jets fuel screws 2 3/4 turns out

The bike is damn near purfect, I think the next day I am bored I will try the bigger jets 142 outer and 145 inner, and see if there is more power to gain, but as it is it runs purfect and has more power throughout with no surges, hoping to gain a little more power up top by using the bigger jets, my bike seems to want more fuel to be happy, my exhaust is not very restrictive, and I run a k&n

 

which jet kit did you get the one I looked at the other day said you would have to drill or tap and should only be done by an experienced mechanic. I don't see how a jet kit would fix the problem that I'm having. If it was a jetting issue I would have noticed it the past two years and if the bad jetting is fouling my plugs faster than normal the new plugs would have fixed me for the next couple of years. Thanx for the info on the jet kit though it's something I've wanted to do anyways.

 

that is the factory pro race kit, you get like 1 extra hp up top with the race kit. the regular factory pro jet kit is all you really need, no drilling involved