Any possible ideas please. I've got a cbr 600 f4i and has started to run lumpy at low rpm. Once over 4000 it's fine and pulls no problem. It's like the bikes in too high a gear and not smooth at all. First thought the battery as this had died twice but changed that and no better. Thinking now pluggs or rectifier? Also put pb ultima fuel in a full tank ago so thinking it might not like it. Anyone else have the same problem?
thanks

 

First of all get red of any suspect fuel and fill in 95ron plus gas. I'd check the fuel pressure regulator before touching the plugs. Do a leak test. Pretty straightforward. Look up videos on YouTube.

 

are you riding at 1-4k rpm? or does it idle funny? if you're riding, then of course its gonna feel like you're in a very tall gear, you've got zero power at that low of RPM.

 

Idle is fine and revs fine in neutral just no good under load . it's when your going round town and if you come down to a 30mph zone and then power up its no good. As soon as you get to 4000 rpm it's pulls all the way with no problems.

 

so theres no issue with the bike, the issue is with your riding. in the situation you just described, you should have just simply shifted to a lower gear to get the engine to an rpm where it actually makes power. like i said before, that bike makes almost no power at that low of rpm.

 

Agree...Below 3k rpm I start feathering the clutch if I cant downshift

 

just got home from taking it for a spin after fitting new plugs. She's running great now. Really smooth low end and pulls as it should. One plug looked a little brown on the ceramic sleeve so think it was failing. Fingers crossed she's good to go now. Thanks for you tips