FYI guys. As mentioned before, we were having troubles with a poorly running 2011 EC250. By poorly running, it was weak off the bottom then hit really hard in the midrange and pulled hard right up to wide open throttle. Jetting helped but regardless of the jetting, the underlying problem remained. With Glenn's advice, I started looking into the powervalve and sure enough, it was not staying seated closed, even at idle, and would open as soon as I blipped the throttle.

I ended up putting a 1.5mm washer as a shim under the spring in the governor under the right side engine cover. You don't need to pull the clutch over or waterpump cover but you do need to drain the coolant. It was pretty easy to do and now the bike performs as it should. It makes great bottom end and lugs down better than any other two-stroke on the market, yet will rev up and run with any 450 in the open stuff.

When I get time, I may try going to an even thicker shim just to see the difference. If you're looking for a shim, a washer the same size as the one that goes between the clutch basket and inner hub works perfectly.

Oh yeah, for jetting we're using a 172 main, 38 pilot, N8RH needle (KTM) in the 4th clip and air screw is 1.5-2 turns out depending on the temperature. Elevation is 2000-4000 feet. Once it warms up more I may drop the needle and switch to a 35 pilot jet.

This is something I need to look into. Some good pictures would help a ton.

It would make a nice photo tutorial sticky wouldn't it.

Mine has rattled on my 08 since new ,but the power has never been an issue So I have been living with the rattle.

It just sounds like alot of trouble to go thru to stop the rattle.

Its very easy. Takes more time to prep the case for a new gasket than to do the adjustment. Its a little strange that these are coming so far out of adjustment. What Steve did was preload the governer spring more. This altered the rest position of the mechanism and took up the free play, but also causes the PV to start opening at a higher RPM.

http://forums.everything2stroke.com/...ad.php?t=45719

Found this helpful when doing mine up. I removed 3 shims.

Honestly guys, it's not hard. I think the whole process took me half an hour and a good 5 minutes of that was spent looking for a suitable washer.

Super dooper noob question, but where abouts are you checking to see if the power valves are closed at rest? Do I have to remove the pipe and peek in from the ehaust port? or do you take the side powervalve covers off? Also, do I need new gaskets if I remove the sides?

Take off the right side PV cover and see if the actuator plate is resting on the stop or not.

I would do the adjustment I described before shimming anything, as it does not alter the PV opening curve. You can shim later as an experiment. Any time you add/subtract governer shims you change preload and starting position of the governer. I feel this should be accounted for in the adjustment, so the actuator is always at the stop with just over zero preload with the engine off. Otherwise, you can have a situation where the governer is in a partially open position at rest.

My camera died some time ago and I really don't have the coin to drop on a new one. If someone sends me a nice DSLR I'll do a very proffesional technical article on the subject.:D

Edit: The other thing that will change this adjustment slightly is the deck height of the cyl., as when you add remove base gaskets. If you have ever owned/wrenched on a KTM, they have a ball joint end on the PV rod that can be adjusted for length to account for this.

I might do a tech article for Directmotocross.com sometime in the future on this.

Is it possible for all of the ball bearings to be dislodged and hidden behind part #26. I have my cover off now and understand the adjustment procedure but I can't see any ball bearings at all.

Please help!