power valve rattle not chain slap

[Noel]

Power valve nut

Hi Guys

I pulled my power valve assemeble apart last night (07-250ec) and discovered a nut at the end on the LHS valve assembly. (I'm the 2nd owner). I havent seen this nut described or illistructed anywhere before, is this normal or has the previous owner done some modifications, note the keeper plate was installed as well.

Also is it normally possible to pull out the PV flapper valve out the exhaust opening, as I cant, I want to avoid removing the head and cylinder if possible.

 

[HydroDog]

Also is it normally possible to pull out the PV flapper valve out the exhaust opening, as I cant, I want to avoid removing the head and cylinder if possible.

I'm not sure if the 250's are the same but on my 300 you lower the piston to bottom dead center, remove the flapper rods, push the flapper up on top of the piston and turn it sideways and pull it out the exhaust opening.

 

[rpduc]

It's unclear to me what you're describing there by "a nut at the end on the LHS valve assembly."

The only fastener inside my left hand cover and on the parts diagram is the socket head retention bolt and washer. (left hand while sitting on bike)

 

[gasser]

My 07ec250 has a slightly different left hand side power valve assembly than my older bikes have. The difference is the LHS assembly has a longer shaft that the 2 bearings fit on and the end of that shaft is threaded. My bike did not have any nut on the shaft.

 

[GMP]

That sounds something like the different drum valve that comes with the adjustable PV kit from France. Did you buy that bike used? My '07 is the same as my older bikes, the drum valve shaft is flush with the outer bearing.

 

[SpeedyManiac]

There shouldn't be a nut on the end of the LHS pv assembly. It is threaded, but no nut required. My 07 is like that.

 

[Noel]

My 07ec250 has a slightly different left hand side power valve assembly than my older bikes have. The difference is the LHS assembly has a longer shaft that the 2 bearings fit on and the end of that shaft is threaded. My bike did not have any nut on the shaft.

Your right- however my bike has the nut which really dosen't do anything.
In a desperate attempt to rid my bike of this horrendous rattle I have installed new bearings and clean all parts. My concern is now it will rattle more, in reviewing the main PV flapper (part #30) you can see a gap of approx.4mm between the two PV assemblies (#31 & 40) thus giving you side -way slap, I was thinking about putting 2 x 1mm washers either side of the flapper to reduce the sideway movement / rattle of the flapper. What do you guys thinks. I read Glenn’s comment that you should get some rattle and I agree but my bike rattle is excessive..

 

[GMP]

Noel,

With the motor off, is your actuator plate resting against the stop bolt head with just a very slight preload? If not, this will cause more rattle at idle and low revs as the PV is never forced completely closed.

My bike is all buttoned up now, but if I have a spare PV gasket I'll pull the left side drum (easy) and take some measurements. It should be easy to determing the total clearance between the parts.

 

[Noel]

Noel,

With the motor off, is your actuator plate resting against the stop bolt head with just a very slight preload? If not, this will cause more rattle at idle and low revs as the PV is never forced completely closed.

My bike is all buttoned up now, but if I have a spare PV gasket I'll pull the left side drum (easy) and take some measurements. It should be easy to determing the total clearance between the parts.

Hi Glen,
I havent put it back togther yet but I will check. Prior to reassembling I have tried to simulate what your talking about by putting some load on the actuator plate (by hand) then with my other hand move the flapper valve and it still has plenty of side way slack and about 1mm vertical slack, hence my thought about putting additional washers either side of the flapper, however this is not my preference, but I need to find a way to reduce/emilinate the rattle.

 

[GMP]

Noel,

The PV flap and left drum are moved by the rod from the right drum, and pivot on the other rod. There must be play here so it operates when fouled, this comes from the clearance fit of the rods in the drum holes, and the slot and pivot hole in the main flap. It adds up and their will be some rotational play in the right drum (actuator plate) when the other parts are retained. What I'm talking about is an adjustment of the belcrank under the sidecover. If adjusted correctly, some of this play is taken up until the PV starts to move, reducing the noise. If its loose, the valve flutters around partially open at idle. My '03 was more noisy than my '00 and '07 and this was the problem. I could hold the actuator plate down to the stop by hand with the engine running and reduce the noise. I have some pics I took when I had my side cover off recently, I'll try and post them later.

4mm sounds like a lot of clearance between the flap and drum sides. It would be nice to get some real measurements from a few bikes. This shouldn't be a wear issue as the parts are steel and have lasted for years.

 

[MattR]

I have some pics I took when I had my side cover off recently, I'll try and post them later.

This would be good to have. Can you provide some instructions on how to adjust the belcrank (when you post pics)?

 

[rpduc]

4mm sounds like a lot of clearance between the flap and drum sides.

I'll bet I have close to that in combined end play from left and right. I did not have the #39 washer in there. Estanka found out earlier in the thread that in his case adding that "missing" washer spec'd from the parts list bound his flapper when open.

I get what you're saying about the preload on the actuator rod Glen. On mine the actuator plate rests against the stop with engine off, but I would characterize the "preload" as very very slight. I could envision it rattling with that slight pressure against the stop.

I just fired her up for a heat cycle after a new top end. I will pull the right cover and see what's going on in there when running. Is it just a "feel" thing when setting that preload or is there some "scientific" method?

 

[GMP]

Yes, just a slight preload by feel. The force is the governer spring acting on the rest of the system. This is not a documented procedure, just something I thought was a logical way to fix my '03 that did not appear correct.

Sorry guys, too much kids sports stuff to mess with photos tonight. I will try to do it this weekend though.

 

[BULTACOBRIS]

Update,
After a closer check it turned out that with the 8X16X1.5 mm washer,
the PV vas binding half way in its travel.
There was NO way i could make my PV work properly with the washer in place. It felt realy good with some play in the closed position, but it would bind half way.

My conclusion is that the washer is machined in to the PV, it certanly looks that way, and the parts list needs an update.

My 08 EC300 also had slop - a washer was placed between the bearings - and no binding happening (told the guy that did it about #39 missing - he didn't notice, but thought it needed shimming, so did the above)

 

[Noel]

Power valve setting

Yes, just a slight preload by feel. The force is the governer spring acting on the rest of the system. This is not a documented procedure, just something I thought was a logical way to fix my '03 that did not appear correct.

Sorry guys, too much kids sports stuff to mess with photos tonight. I will try to do it this weekend though.

Hi Guy’s

Reassembled cylinder and PV assembly and noted that with the engine off the exhaust valve bracket (part#35) was not resting against stopper bolt (part #33). The gap between both is about 5 mm, then in lifting the stick lever rod (part #1) it is evident that no preload is on the stick lever, thus allowing the stick and the bracket plate to move freely back and forth and hit the stopper bolt Part #33-

Is this my dreaded rattle I hope so.

So, how do I adjust the PV assembly to put some preloaded on the stick / valve bracket to reduce the possibility of the bracket moving back & forth hitting the stopper bolt.

This rattle is doing my head, not to mention my wife is frustrated with me obsessing with my bike- again.

Refer photo:

ttp://picasaweb.google.com/hoff49/MyPictures?feat=directlink

 

[GMP]

Noel,

You have one of two problems, both require removal of the side cover. After the oil, coolant is drained and the cover is removed, you need to verify that the PV governer balls are not displaced and jammed, as this will prevent the PV from closing. This is usually caused by pulling on the actuator rod with the engine off, manually moving the governer and allowing the ball(s) to fall out of position. If this is the case you can manipulate the governer to reseat the balls.

If the governer is OK, then the position of lever #6 on lever axel #4 must be adjusted. Loosen setscrew #5, fix or hold the actuator plate to the stop bolt, and while pushing the governer assy straight into the case with a grip that will put just a slight preload on the governer spring, tighten setscrew #5. Its eaiser to jam the actuator plate against the stop with something unless you have a helper to hold it there. Its obvious when you have the side cover off. The idea is to provide just a slight preload (closed) to the mecanism by the governer spring. You may have to do it a couple times to get it right.

I'm sorry about no photos, but this PC has some USB system issues and my thumbdrive with the photos takes a very long time to be seen by the system.

 

[rpduc]

O.K. for future reference here's a report on my "rattle."

I rode the bike for about three hours yesterday and did not produce the rattle. Previous to the top end job it occurred regularly when pulling hard at low rpm. Must have been piston slap like someone else reported a while back. Cyl. replated, new top end = no more rattle in those "lugging" situations.

I did not put the "missing washer" in. (#39) I still have a lot of end play in the PV assembly. I wanted to think it was the PV because that would have been easier and cheaper, but it obviously was not. I couldn't quite envision how too much end play could cause a rattle like I was hearing, but that optimism...

I can definitely see that a misadjusted actuator rod like Noel has could do it.

 

[BULTACOBRIS]

So how much rattle is too much?
This is my first modern 2 stroke - at low to mid revs mine sounds like a chain slipping over a cog (not loud though)
Is this the norm please?

 

[Noel]

Hi Guy's
Pulled off side cover to review the balls in the PV governor, I can see the balls only at the lower part of the governor, does this mean they have fallen out of position, if they have does this mean I have to disassemble the governor to reposition them or can I reposition them by laying the bike on it's side then pushing the governor inward then manipulating the balls into the correct position.

Need to get this sorted, didn't ride on the weekend, we had plenty of rain this week in the land of OZ - perfect for the Gaser

 

[rpduc]

So how much rattle is too much?
This is my first modern 2 stroke - at low to mid revs mine sounds like a chain slipping over a cog (not loud though)
Is this the norm please?

Very difficult to quantify over the internet. I was in the same position last summer, new to modern two strokes and used bike with a rattle that just did not sound "right" to me. I rode it for the summer hoping it was one of the "normal" rattles people here described but it seemed to get progressively worse. This winter I had it out on the ice few times and decided something was not right. Seems to have been piston slap in my case but I'd think that unlikely on a '08 300 unless it's been ridden a lot.

In my case the rattle was more consistent when pulling down low than the rattles others described as more intermittent or occasional and attributed to chain slap, PV etc.

Sorry haven't delved into the PV govenor.