Hi can anyone help me I have a 650 gs , from 2000 and it stutters at 60-65 then is fine at 65-80 then after 80 it stutters again. No matter if i accelerate slowly or progressively the same happens , Can anyone help please.
Make sure that the air intake sensor is connected.(It is sometimes forgotten to be reconnected after a service). Switch on the ignition but do NOT start the bike.Twist the twistgrip fully and back again a couple of times.This will reset the computer.Switch off and it resets itself.
Hopefully,this may help.
Starting the bike with an open throttle can confuse the "computer" too.
If resetting the computer doesn't work, then you'll have to ensure that valve clearances are correct, the air filter good (new) and new spark plug fitted, before tracing the problem further.
Other suggestions might be the coil/HT lead "leaking", or a faulty fuel pressure regulator/filter unit.