power valve rattle not chain slap

G

gasgasandrew

New member
HI have read many members with 2 stroke gasgas bikes with a rattle that seems to come and go my 07 ec250 does this on open trails [ ITS NOT CHAIN SLAP] what i have fould is there seems to be a lot of clearance in the power valve and at steedy speed the center flap slapes from side to side at just the right revs may be pulse in pipe what I would like to no is this a problem or do i just leave it alone as its very hard to get it to do it it just happens now and then at these revs or can i space the outer bearings to close up this clearance as i can close it up by pushing in the left hand bearing under ther power cover any help would be great
 
No help here, but Misery does love company

I thought it was chain-slap too, and I have been told such in the past. A new chainguide and sliders and a lot of checking the chains' range of motion has pretty much taken the chain-slap theory and tossed it out the window.

You are absolutely right, it just seems to happen at times. For me, it is mostly at high RPM while hauling a$$ across a big sand dune. It just sounds like a rattle in the motor.

I have been able to reduce this noise by putting enough of a bend in the actuater arm to apply a little bit of pre-load, so that at WOT the flapper is pushed more firmly against the stop. It seems like there was enough slop in the powervalve that it could kind of flap (or vibrate) like a reed on a saxiphone. I never thought about side to side motion though.
 
steedy speed the center flap slapes from side to side
Click to expand...

Are you confident this is causing your rattle? I have this same sloppy endplay situation but I can't quite envision how it could cause a consistent rattle. There was a washer (#39 on the parts diagram from my '05) missing when I disassembled the PV. I guess that's happened more than once. I ordered the washer from GF but it came wrong. 6mm i.d. instead of required 8mm. The part # size correlation is wrong at Gofasters. Mark was going to check on it so remind him if you order one. The bike ran fine all last summer and I assume also for the P.O. so I reassembled without the washer but now you have me thinking I need to find a washer... the parts list says 8mm x 16mm x 1.5mm
 
Hi pull off the pipe and covers and rock the flap side ways and what you will get is the same noise that you get when it happens when running at the right revs .the noise is not consistent its randome right revs right load sounds like a ball bearing rattling in the camber never happens in single trails or full power only light load on open trails and is very hard to get it to do it and only last for split second and then stops until the next time revs and load are right mostly at steady speed . there seems to be to much clearence we need gasgas to put closure to this as a lot of 06 07 ec are making this noise if its not a problem ok but what damage will it do in the end
 
How about trying a wave washer on either side instead a regular washer?Allows side to side but with some cushioning effect and perhaps less likely to get gummed up.
 
You guys new to GG should just relax and ride the bike. All 2-stroke power valves rattle somewhat and at different speeds, usually at idle. The powervalve has a lot of clearance for a reason, so it can operate in a dirty environment. Any experience with military firearms? Somewhat sloppy fit by design to work in dirt and be totally reliable, same idea. The parts are all steel and ride in bearings, its a simple and reliable design. No gears, o-rings, timing, etc. It has been this way for years now and if you know of a powervalve failure please let me know. I've seen them with 6K miles, 4K miles, and my own previous bikes over 2K miles.

If your actuator plate is not touching the stop bolt head with the engine stopped, there is an adjustmet under the side cover to correct this. If its WAY off, likely you dislodged a ball in the governer by pulling on the rod as was diwcussed in another thread.
 
As Glen said the system has some built in slop, however all three of my bikes came to me with play in the actuator arm. An Easy fix once the side cover is off. I had the pipe off last night and to my suprise the pv would slide back and forth a couple mm. Neither of my other bikes had this play. I suspect I am missing a washer somewhere.

The noise that bugs me is the clutch whiring. When the clutch is pulled in the bike is quite. Once the clutch is released the bike makes a very noticable whirring noise. Supposedly normal but neithe r of my other bikes made that noise. I suspect the basket is not perfectly weighted. I still love the thing and am in the middle of a big round of maintinence. Reeds, Exhaust repack, pipe reseal, numerous chasis rub points mitigated etc.
 
In my brand new 08 EC300 the washer shown in the parts list on the left side
was not fitted (item #39).
I am going to find me a 8X16X1.5 mm washer and fit it as shown in the parts list.
 
enstanka said:
In my brand new 08 EC300 the washer shown in the parts list on the left side
was not fitted (item #39).
I am going to find me a 8X16X1.5 mm washer and fit it as shown in the parts list.
Click to expand...

Just a question.. why would this part be missing from the factory? My bike was missing the washer in the rear wheel bearings from the factory. I looove my Gasser but is there this many faults from the factory. Just a question, definetly not bagging the brand :confused:

Regards

Adam
 
I had the pipe off last night and to my suprise the pv would slide back and forth a couple mm. Neither of my other bikes had this play. I suspect I am missing a washer somewhere.
Click to expand...

I thought the endplay seemed excessive on mine and the washer is not there. With this many bikes having the "missing" washer I wonder if maybe they changed the design at some point, omitted that washer and didn't update the parts diagram. Can anyone with a newer bike confirm the presence of that washer? I know if you order that washer from Go Fasters by part # it won't fit.

In my brand new 08 EC300 the washer shown in the parts list on the left side
was not fitted (item #39).
Click to expand...

Just a question.. why would this part be missing from the factory?
Click to expand...

It would be nice to have an "official" opinion on this. My MC ran fine all last summer without the #39 washer, but it's simple to install if it's supposed to be in there. Mark at GF seemed surprised when I told him the washer he sent was incorrect. Maybe he's looked into it.
 
I have now fitted a washer (#39) with the dimentions 8X16X1.5 mm, as in the description for #39.
The washer fitted perfectly, reducing the axial play to a few thenths of a mm from almost 2mm.

The missing washer, is this a change in production, well who knows.
The washer sure fitted perfectly in my cylinder.


//
 
thanks everyone i think we have fixed this problem once and for all as i have been watching the forum and it seems this problems been going no where but because of some great forum members that pulled there pipes and valves thanks again
 
Chattering 07 250 ec

Hi Guy's

I have enjoyed reading the information on the power valve chattering/rattle. My 07 250 ec also has this horrible noise, which I cant ignore, the noise is mostly assoicated at low to mid revs. I also can move the central exhaust valve from side to side so I'm assuming this is the cause of the noise so I will pull apart the PV assembly "looking" for the problem/resolution.

Various posting have noted that the washer (Item 39) was missing and they have replaced it,but no one has noted if this stop the chattering of the valve.

If I have the washer fitted,I suppose I will replace all bearings and hope for the best.
 
Do a search and read the other threads. Yes, the washer should be there. Too much noise can come from the PV not adjusted to the stop, or a bad bearing but this is less likely. I'll say it again though that they all rattle some at low revs.
 
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.

//
 
I havn't had my '07 apart yet, so I can't comment on the washer issue related to it. The '00 and '03 had it for sure. What does the drum valve look like? Is there a shoulder machined on the bearing side? What we need is dimmensions of old and new drum valves and main flap, that would answer the question.

I do remember my '00, my first GG, getting louder in the PV area after a top end rebuild and total PV cleaning. Reason most likely being the carbon that had formed on the parts and took up clearance had be stripped off.
 
What does the drum valve look like? Is there a shoulder machined on the bearing side?
Click to expand...

Yes, on my '05 there is a shoulder machined on the bearing end of the drum valve.

The "hat" spacer on the other side was also VERY sloppy so I picked up a new one and it's just as sloppy as the old one.

Hopefully most of my "rattle" was from my tired top end (which I redid) but I haven't run the bike yet to find out.
 
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