Hi wonder if you can help, my friend has a 1998 CBR 900 RRV, and the bike is stuttering above 7k, in fact it just wont pull past 7k.

It idles fine, runs fine upto 7,000rpm but after that it misfires and just wont pull.

Does the same just revving it up in neutral, fine all the way to 7k and then missfires.

We've drained the fuel out, put fresh fuel in, taken the carbs off, stripped them down and checked them over, and there fine, checked all the electrics, theres no shorts, all connectors are good, and still the problem persists.

My only thoughts are with the CDI unit, but as i've found out in the past if the CDI unit is the fault the bikes wont ussually start.

And as used CDI units are rather expensive i'd thought i'd ask if anyone else knows what could be the cause before we buy another cdi unit and find out its still doing the same thing.


I've searched high and low over the internet for a simular problem, but i've found absoultely nothing.

Any ideas???

 

Check the ignition timing with a standard timing light. The timing mark should move smoothly as you rev the engine. I bet it doesn't. If the timing doesn't advance correctly, the pulse generator is bad. If the timing is ok, check the plug wires. An easy way is to run the bike at night and look for sparks coming off the spark plug wires.