I have an MK Indy Blade

it has a CBR 900RR Fireblade 918/919CC engine

it pulls really well in first and second, but as soon as I get to about 60-70MPH

it seems to be a little hesitant, almost like a missfire at about 70MPH and doesn't want to pull any more.

I have bought new spark plugs to fit this weekend, and I was going to try and change the fuel filter but the one I have isn't like for like so it isn't long enough without changing the pipe work.


Any other suggestions?

Try balancing the carbs/TBs.

When I changed the exhaust on mine it had similar issues, have you changed anything, exhaust/inlet as these engines are very sensitive, went from standard R1 can to straight through, to address i fitted a dynojet kit.

New plugs are also a good start.

Check the plugs before replacing them. Might indicate that one carb has restricted flow.

Many thanks guys.

Runs like a dream up to 75ish so I'd imagine it's only something Small

I will check the plugs tomorrow and see if I can see any evidence of a restrictive carb.