Splutter Problem I have a problem with my 1998 Aprilia RS250, when I open up, as the bike hits power band it starts to splutter. When I change too third it starts coming right, what can it be.

Hi, What Fuel/oil ratio are using?

I'd strongly suggest 40:1 with fully synthetic 2T oil and premium fuel.

How is the bike's compression? It should be165-215PSI. If it is less than this install new correct size piston and rings and use new gaskets.

If the bike is still splutter and blowing lots of smoke then raise the main jet needle by one notch.

Sounds like either the bike is starving for gas at higher RPM's, or you're hitting the rev limiter.

try cleanin the throttle body with nonchlorinated cleaner-inspect idle air also and egr--make sure plug wires r not old and inspec distributer area--secure a shop manual

i have a 92 rm 250 an i just had it fully rebuilt an it laggs in power band an splutters an feels guttles

hi mate when you put the coolant do you bleed the system to get the air out of the cylinder

Hi and welcome to FixYa,

Your described problem could be the battery but I am also inclined to suspect the voltage regulator. If the 'splutter' is when revving/higher RPMs, then the CDIs are cutting off possibly because of higher than normal voltage from the regulator and/or the battery is not loading the system(charging). Try charging the battery externally for at least a couple of hours, try and observe. You can also have the battery tested. If the battery checks good, accepts a charge and the bike will run normally after being charged, then the regulator must be considered.

Good luck and thank you for using FixYa.

Hi ....... The excuses you've been given might hold up either in Oz or tibet but as you say in Ireland it doesn't quite hold water.
Has anyone changed anything ? Pipe, airfilter, ignition ? The fact it takes off in the powerband show it's either not too bad or you've been luckey not to hole a piston. Try removing the spark plugs and note the colour, any colour other than a light tan is NOT correct and indicates fuel mixture as too lean/white (too much air) or rich/black (too much petrol). Too rich is preferable to too lean as being lean will hole a piston, burn out a valve or a partial/full seizure. Dependant on colour I'd then LOWER the circlip on the carb needle.
Let me know how you get on.

check the 4 stroke oil if it starts to splutter at half throttle