Hi i have got a CBR600 1996, It revs cleanly when stationary, but when moving it will not rev past 4000rpm, or go faster then 30mph, applying the choke has a slight effect but nothing major and get the odd burst of power in 1st and 2nd but in general it just slutters and judders all the time,
so far the plugs, CDI, and coils have all been changed, the carbs have been stripped and cleaned and have even tried different sets of carbs, none of this has had any effect it feels like a fuel problem, but the pump is working nornallly....please, please could someone help me as i am out of ideas
many thanks

 

Did the bike run ok before you changed the plugs, CDI and coils or has it always run rough on the move? Check the ignition timing at tickover and rev the engine to see if it advances. As you suggest, it could be fuel related and normally it is a low level of fuel in the float bowls that is the problem. However I don't think that it is in your case. Is the CDI a new one or second-hand? Could be a blockage in the fuel lines or an air leak. If it is possible, you could check the flow of fuel from the pump by disconnecting the supply pipe and discharge the fuel into a bowl to see how much fuel flows and the pressure it is flowing at. As you have tried carbs off another bike it looks more likely to be a fuel supply to the carbs issue. I assume you have checked the fuel filter? Hope you sort it soon!