'91 power valve actuator help

[Vincenso31]

Hi, i have a '91 kdx 200 and was wondering how to tell if the power vavle actuator (the lever arm that comes out of the bottom end) is opening or moving back and forth properly. Should it open and close when the engine is in neutral if you rev the engine?? Ive taken the small plastic cover off of it to see and i dont notice any movement there when I rev the engine.......The service maual doesnt really say.....If it doesnt open properly, how will the engine perform?? Im kind of a newbie with this dirtbike stuff............Thanks!

 

[canyncarvr]

Commonly, your bottom end will stink ;)

Yes, when revved in neutral the power valve will activate (if it's not broke, and you rev it high enough...usually around 6k).

You can take the pipe off, look up inside the exhaust port and manually activate the powervalve by turning the activating rod. (Don't use this method to test it using the 'rev in neutral' idea. ;) )

Earlier kdx models (< 95) are notorious for failed power valves.

 

[G. Gearloose]

Not certain if it appies to you but,
When my '91 had stock jetting and airbox cover, it failed to hit the rpms necessary to actuate the PV; even in neutral!

Jetting cured both 'problems'; gives an idea how rich thay come from the factory.

Remember the nut on that lever is left-hand threaded.