Powervalve issue?
 

Hi guys,
We're having an issue with a 2011 EC250 (my girlfriend's bike). When we picked it up in March, the bike ran great. It pulled strong from the bottom all the way to pinned. All was well, but now the bike is really soft on the bottom then hits very hard in the midrange and pulls well through to revved out. At first I thought it was jetting, but after playing with that it seems to be lying somewhere else. A few people have suggested I check that the powervalve isn't stuck open, so I did.

The powervalve isn't stuck open and seems to operate okay. I did notice that when I had the idle turned up and the choke on, the powervalve mechanism flutters (actuating plate behind the right side cover rotates approximately 60 degrees clockwise). Once the bike was warmed up, the powervalve remains shut at idle but as soon as I twist the throttle, it opens about halfway, then at maybe 1/3 throttle the powervalve is all the way open.

To me, it looks like the powervalve is opening too soon. Any idea what RPM it should be opening and how fast it should open up?

I'll bet I know, sounds like my '03 was. Soft low end and a lot of rattle. The bellcrank setscrew is either loose, or the main adjustment is off allowing a large amount of free play in the mechanism. What is happening is the PV itself is just floating around under pressure of the exhaust pulses. You need to pop the side cover off and adjust out all the free play. Everything else in the PV system is set by mfg tolerances.

This sounds like the same sypmtoms my 08 is having. Can you explain a little more what you mean by the bellcrank setscrew and which side cover you are referring to.

My 2011 has the same symptoms. It's been that way since new. I thought it was jetting also, but I've pretty much got it running strong.... all but the bottom end. I guess I didn't think about the power valve. Please explain what to look for and how to adjust it if that is indeed the problem.

To get the free play out, do I need to shim the spring or adjust the position of the actuating arm coming off the governor? I checked and there's no loose screws in there.

Hold/jam the PV actuator plate up on the cyl closed.

Preload the PV governer spring with a .005" to .010" feeler gauge (not that critical). I used to do it by feel but this is easier and consistent.

loosen the setscrew on the bellcrank

Push/hold the governer assy fully into the case bearing, be sure its straight, and
tighten the setscrew

Remove feeler gauge and replace the side cover

The idea is to remove all freeplay and end up with just a VERY SLIGHT preload, so the actuator is held to the stop.

I took the side covers off and started the bike to see what happened with the linkage. On the left side the bearing moved in and out about 1/8" at idle. Is this normal? Also the shaft that the bearing is mounted to has threads but no nut. Is that right?

On the right side the actuator seems to open at the right time. I'm going to guess about 5000 rpm. With the engine off the plate is not touching the stop. About a 3/16" gap. I'm not clear on the advice to preload the spring. Do you loosen the bolt that the connector from the bottom is attached to? Do you push the plate up or down against the stop?

No nut required on the left side.
http://www.gasgasons.com/html/imgmec...appement-3.jpg

The transmission right side cover has to be removed to access the power valve actuator.

While you're in there, take out the preload shims, if any.
I think you'll like it ! I sure do. It's counter-intuitive that the power
valve will open sooner, for "better" low end, but it works !



Jeff

gasgasman is right. My 07 gasser has the threads but no nut. my 01 and 99 gassers did not have the treads.

I saw this thread this morning and this is what I came up with to take up the extra 'slack' in the mechanism. I only took off the powervalve cover, and didn't fool with taking the transmission cover off.

I made this from a small spring I got for $.50 at the local hardware store. I cut a small notch into the powervalve shaft with a Dremel. I then looped the end of the spring around the allen bolt. The spring tension itself is very light and only keeps the shaft from flapping around. Hopefully it won't delay the valve opening by much if at all.

I will report back in a few hours after a test run.

Test ride done: It was ok......

It delayed the hit a little longer then it hit harder.

The powervalve was quieter.

The spring popped off toward the end of the ride.

If I need to JB weld it into the slot for the day in the trails to make a full determination.

That's interesting. Maybe it might be easier to do something similar on the RH side - more bits to attach a spring to... you've got me thinking now!

On a second note, anyone realize that the bearings in there are interchangeable with rollerblade and skateboard bearings? :D

That is not the same thing at all as far as removing free play. You adjust the free play out as discussed, and then play with PV shims if desired. What you did is what the Trusty PV cover does, in one direction.

Just to be clear, if someone wanted to adjust shims and free play, they would need to drain the coolant, remove the pipe, take off the water pump, clutch and transmission covers correct?

Yes, you have to remove the primary side cover, but if your actuator plate is on the stop with the engine off then there is no need. If the plate is off the stop, there can be excessive movement and rattle, and in severe cases a softer low end as the PV is open slightly. My '03 was way off like this, but it is rare.

OK< as of this morning, I looked at both sides after taking the pipe off. On the right side where the hook/arm comes up and works the valve, there was a little triangle piece that was next to an allen bolt stop.

The valve was not resting on it, but was hovering about 4mm away from it. I could look into the exhaust port and by working the mechanism a little I could get the valve to move further toward the piston and the triangle piece to hit the allen. If I let go, it opened back up again.

So you would recommend me take the case cover off and shim this up so it stays closed? I do have a noticeable rattle in the lower range when accelerating slowly.

That is exactly what I'm referring to, and you can correct it with the adjustment. Its an adjustment of the arm in the mechanism on the shaft via a setscrew, not a "shimming". The "triangle piece" is the actuator plate.

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!

Do I need to take the waterpump impeller off to get the case cover off...didn't want to force anything.

Is it a lefty loosey or righty loosey on the impeller shaft?

lefty loosey.

You do not have to remove the water pump impeller to take the case cover off. The opposite end of impeller shaft sits in a bearing race and can sometimes be tricky to remove but it should pull straight out without having to remove the impeller itself.

yeah...it was just not wanting to come and didn't want to get too physical with it.

Is it possible for someone to take a few more pictures and post next time they dive in. I'm a bit of a girl when it comes to tackling things head on for the first time.

I'll hit up the dealer for a few power valve gaskets and a clutch side one too.

I test rode a friends 2011 EC300E and immediately I realised just how rattly my bike is both at idle and when giving light revs at idle. Mine sounds like its going to explode compared to his. Then riding his, it felt much stronger right off idle. Mine definately had more hit in the mid and a ripper top end. Could be jetting variances but the rattle is definately not jetting related and has been there since day 1. I thought it was normal.

One more thing. When you say take the right side cover off and run the bike to ensure the governer is working as its meant to. Is this with the pipe on or off?

Is there any harm in firing the bike with the pipe off for diagnostic purposes?

Every time iv heard that pv check mentioned, its with the rhs cover off and pipe on, but it only takes a few seconds to put the pipe on, it just sits there, dont bolt it on.

Thank noobie. Will have a look see. I have pulled my P3 Guard off so will give the pipe a good clean while its off. Going to throw some fresh o rings on it too. Big thanks!

Had a look.. Powervalve is against the stop. Seems to be quite a bit of play where the arm attaches to the actuator plate. There is a floating washer in there that vibes alot. Still couldn't pin point the sound my engine makes just off idle. If you give it a quick rev theres quite a bit of vibration felt and heard. Pulling the choke and making it super rich doesn't change it so I don't suspect jetting. Are some of these engines just noisier than others? The one I compared to only had 600km on it, but I recall mine always being a bit loud and vibey

Here are some photos of the adjustment being done to my bike. I can't provide a detailed description of the procedure since I don't know the names for most of the parts, but I wanted to get some photos posted so people could see the powervalve mechanism. You'll need to remove the pipe, kickstarter, drain the coolant from the water pump drain plug, remove the radiator hose (use pliers to squeeze the spring clamp) and lay the bike on its side. Remove the side case by loosening the appropriate bolts. You will need to remove some of the clutch cover and water pump bolts because they hold the side case on! These bolts will be noticeably longer than the others and they must be removed. Tap the case lightly with a rubber mallet to loosen the gasket. Lift the case off, it may take extra nudging near the water pump area because of the drive mechanism. Now look at the photos. The bolt marked "adjust here" is the screw that you need to loosen. The next part is tricky, you need to follow Glenn's advice and figure out which way to rotate the adjuster (and how much) to get rid if the slop. You'll need to use both hands to hold everything in place while you re-tighten the Allen bolt as everything can flop around when this bolt is loose. I did not change the shims on my bike. Now you can reassemble the bike (new side case gasket goes on now if needed) and replace the coolant.

Steve

Thanks heaps for those pictures!

I inspected my power valve through the right hand side cover and its operating well. There is still a bit of play in the valve itself while the actuator is up against the stop but I believe this is normal.

I made a jetting change afterwards to try and identify the source of my rattle and vibration and low and behold, dropping the needle one more clip position cleaned it up alot, but I'll put that in the 2 stroke carb section.