hi, i have a 96 cbr600ft and it was fine until i got a hole in the exhaust downpipes, i changed these for some secondhand pipes and i changed the 4 gaskets for the downpipes that fit in the engine, i also changed the gasket that joins the pipes to the end can, all seems fine until i get to between 60 and 80mph then the bike stutters and struggles to pick up speed, once i get past 80mph the bike is fine and its fine under 60mph, i have checked to make sure nothing is blocking the pipes and there doesnt seem to be any leaks, does anyone have any idea what my probem could be? i cant remember if this started at the exact time i changed the pipes but i know it was close to that time
thanks

 

If it only happens at a cerain RPM then it is a fuel problem in your carbs. Probably just need a cleaning. Also sometimes spark plugs will do weird things at certain RPM's. Could have a bad one. Plugs are the easiest.

 

thanks for the reply, after being out on the bike today for a while, it seems to be stuttering at around 6000rpm

 

+1 on the carbs or plugs

 

My F3 is hesitating between 2k and 3k rpm... I'm thinking that the lower rpm jets are clogged. Hopefully running Seafoam through the gas will help, otherwise I'll have to have the carbs cleaned. Sounds like you could be having a problem with the main jets clogging, but then I'd think that it would hesitate at all higher rpm. Maybe it is your plugs, like others have said.

 

Yea I am sure your carbs will need to be cleaned.

 

I am having a much similar problem with my '95 F3, there I was happily weaving through the traffic heading home from a great run out and the bike started to stutter, quite unnerving when passing an arctic (US: juggernaut??). The thing is, it started off as a simple stutter but then felt as if she was completely choking. I pulled towards the hard shoulder dropping down through the gears each time giving it throttle hoping she was going to cough up what was choking her and come back to life. I was down to 2nd gear and 1.5K and abracadabra she was alive. This has happened 3-4 times in the past 6 months, but slightly more annoying is the lack of willingness to start after a run of about 1-2hrs which as you all can imagine really pisses me off when I stop to fill the tank, you come out of the shop go over to the bike press start and "nada" "zilch" "nothing" not even a half hearted attempt. The lights come on the dash but thats as much life as she shows, so the first couple of times I walked away in disgust, thinking maybe it was an overheating issue and if I give her some time she would respond with a satisfying growl when i push her buttons. Oh how wrong I was, guys it feels like, you know when you have been out for a couple of beers down your local, slice of pizza on the walk home, everything is good in the world. You get in the house trip over the dog, stagger upstairs, strip off, feeling great!! slide into bed beside the wife/GF/husband/BF give them a gentle touch on the rear end and all you get is "nada" "zilch" "nothing" not even a half hearted sign.
So back to the mechanical issue 1st time it stopped it stranded me in the middle of nowhere (Why does it always happen there???) I gave it approx 2hrs to cool off but no good, so I called the cavalry the turned up loaded bike on trailer and drove home, on reaching my house I wondered if she would go now and sure enough. 2nd time I gave it again 1hr came back, no good, walked the bike 100yards down the road pressed the button and woohoo off she went, not by bumping I hasten to add. Then just recently nothing would have it but she needed a bump to get going.

So if anyone can help me out with my series of probs that would be wunderbar!!