Why is my cr500r sputtering?

Question

the bike runs great at a low to med rev when in gear but if you hit more than half throttle it starts stumbling but only when in gear

Answer 1

more than likely you have gunk buildup in your carburetor's emulsion tube or high speed jets. either tear down the carburetors to clean off the varnish and gunk OR run some seafoam through your fuel system to get rid of it. that cures most problems. if its serious tho, your gonna need to take the carbs apart and clean them by hand.

you can get Seafoam at walmart, autozone ect. they will know what your talking about.

Answer 2

You may have an air leak around the intake.

Answer 3

try changing the gas filter and cleaning the airfilter.

Answer 4

For future reference, always give year, make, engine size and model # when asking questions. We need all of that info to give an informed answer.

Sometimes the year can make a difference.

Check the reed valves.

They might be weak and not sealing properly.

When it starts stumbling, hit the kill switch, remove the spark plug and check it.

If it's on the light side, the crank seal (flywheel side) could be leaking.