My 1990 rmx250 would not rev up high then it died out is that just a spark plug?

Question

im thinking its just needs a spark plug replace cuz i just had lots of engine work done

Answer 1

Check that the slider needle has not come loose and is sitting in the emulsifier tube. The slider is located at the top of the carb, unscrew it.

Answer 2

Spark plugs USUALLY spark or don't spark. If the plug is working at an idle chances are it will work at high speeds.

Sounds like ignition or carb problems.

What kind of engine work did you have done?