clacking noise

[getndirty]

Just did a top end a few weeks ago, everything went well - decided to try to clean the power valve assembly as well - got the pivot rod out but couldn't get the control rod out, so since it was working fine before I just buttoned it back up.

Bike seems to run fine, but I now get a clacking noise when I let off the throttle - when I'm holding it at a steady pace - not accelerating or decelerating. I was careful when I took the jug off the bike to not pull on the pv push rod. Last weekend I took the right side clutch cover off, and and set a little pre-load on the pv pushrod - that didn't fix it.

So I've got the bike back apart once again - with the screws/bolts removed from the pv control rod, I've got a couple mm's of free play between the right and left side. If I push the control rod all the way in from the right side of the engine, the flapper valve is pretty snug - with it pushed the other direction, there's that same 1-2mm of free play in the flapper valve. When I rattle the valve from side to side, it sounds really similar to what I get when the bike's not under load.

1) Is there a way to eliminate the rattle??
2) I've read about loose clearances since it has to work in a less than ideal condition, but this seems excessive to me - will it hurt anything to (continue) to ride it like this?

 

[gasgasandrew]

Hi had the same problem look under [ power valve rattle not chain slap ] thread and this will clear up your problem my bike had the same issue just set the preload on the power valve fixed mine and gave me a heap of low to mid torque some have the problem some don't good luck andrew

 

[rpduc]

"Excessive" endplay seems to be normal. I'd say mine has a good 2mm. And mechanically I think it would be hard for end play to produce that clacking.

Are you sure what you're hearing isn't chain slap? I didn't believe that sound could be chainslap either but on mine it's obviously that when lugging in higher gears. I've even confused chainslap from someone else's bike with motor noise on mine. Last enduro the guy ahead of me on a transit section had horrible chainslap... we were both getting on and off throttle in such a way that I'd have sworn that noise was coming from my bike when letting off throttle, and that she was going to blow any minute... I finally got up close to him and could see his chain rattling and put 2 and 2 together.

I wonder if anyone has tried setting the chain a little on the tight side just to see if that would eliminate chain slap?? I wouldn't leave it that way, and I'm not sure if a too tight chain would stop the clacking anyway, but it might shed some light.

 

[getndirty]

Thanks for the replies - I'll get back in the engine this evening and add a little more pre-load - hopefully that'll fix the issue. If not, I'll try tightening the chain - a little more - to see if that fixes it.

I have to say though that after putting over 300 hours on the bike in a year, I have some doubts about the chain slap - but I've been wrong plenty of times before (hopefully I'll be wrong again on this one because I've got a race coming up this weekend).

Thanks again!

-Al

 

[getndirty]

"Excessive" endplay seems to be normal. I'd say mine has a good 2mm. And mechanically I think it would be hard for end play to produce that clacking.

It almost sounds like a flutter - it's not regular (in time with the engine or tire rotation or anything else that would be happening at a steady pace).

I've even confused chainslap from someone else's bike with motor noise on mine. Last enduro the guy ahead of me on a transit section had horrible chainslap... we were both getting on and off throttle in such a way that I'd have sworn that noise was coming from my bike when letting off throttle, and that she was going to blow any minute... I finally got up close to him and could see his chain rattling and put 2 and 2 together.

...traffic the other day, I could swear I was about to have to do the brakes on my truck again - whoever it was was squeaking every single time I hit my brake pedal. Point well taken - last time I rode it, I took it on a short 5 mile loop by myself to make sure I wasn't picking up on someone elses rattles.

 

[gasgasandrew]

I know its not chain slap and I know the side play in the main power valve flap [ move it side to side throught the pipe flange make the same slap noise ] preloading the valve has fixed my rattle 98% the other 2% is the flap movement that i will fix when I do a top end by making a lash washer [ see power valve strip down number 39 washer ] . this rattle only happens on part throttle transit sections where revs are steady and the valve is at rest on normal trails where the bikes braking traction the valve is moving all the time and is never at rest there is no rattle GOOD LUCK this issue has done my head in bike is heaps better now its be preloaded and awsome power delivey

 

[getndirty]

Andrew - that's exactly what I was trying to describe. I got back in the engine and added a little more pre-load last night. More than I would like to have added, but I'll know after practice Saturday morning if it's gone.

 

[rpduc]

Yes, good luck. Let us know how you make out.

Andrew - that's exactly what I was trying to describe.

That's the experience I was trying to describe with other guy's bike scenario

I got back in the engine and added a little more pre-load last night. More than I would like to have added, but I'll know after practice Saturday morning if it's gone.

That also describes my attempt at preloading the PV rod. It did nothing to eliminate my clacking, but I hope it works for you. I know how irritating that sound is. Maybe mine slipped... it is a pretty cheezy set-up in my opinion. Seems like a lot to ask of a set screw on a round shaft.

(I'm still bettin' on the chain)

 

[GMP]

From almost 10 years of riding and wrenching these bikes, I found that the PV noise seems to get worse after a top end rebuild and PV cleaning. Why? I think because all the carbon and spooge that dampens the sound and takes up clearance is removed. Perhaps you dislodged something like this, nothing else in the mechanism was changed, correct? The mechanism is loose by design as discussed before. Why could you not remove the control rod? Its captured by the drum valves and can be removed by first removing the right side drum and bearing, thread the actuator plate bolt in the drum, grab it with pliers, and pull it out.

The GG PV is actually pretty good. At first it seems "cheesy" compared to say a KTM, but its simplicity and durability (all steel parts) are evident after owning the bike for awhile. The Japaneese bikes use aluminum parts in more complex designs with racks and pinions that wear and foul and rattle worse. KXs and KDXs are real noisy. The KTM is full of o-rings and much more of a hassle to service.

The point is I would not sweat the rattle. If your sure you did the top end right, the PV is assembled correctly, and the slop removed from the system as I have noted, all should be fine.

 

[getndirty]

Correct - nothing was changed in the mechanism. I followed Uwe's instructions to the letter. When I threaded the actuator plate bolt back into the drum and tried to pull it free, it wouldn't budge- not a single bit. I tinkered with all the moving parts to make sure they were moving freely, decided not to force the issue and buttoned it all back up. I've ridden the bike several times since then and while it runs fine, the clack is annoying but doesn't seem to affect anything. Next time I do the top end I'll get a little more aggressive.

...I'm also getting a 2003 EC200 in a few weeks - it'll need engine work and I've been told the PV is the same on that one, so I'll have another engine to compare notes with.

 

[GMP]

Warm the cyl area around the drum with a propane torch, use a longer M5 bolt to grab all the threads, it should pull out. The MC250 has the same PV parts.

 

[getndirty]

For the official record. After adding even more pre-load to the pv, the flutter is gone, but I now get a discernible clack when I chop the throttle. Like the pv is snapping shut. Raced the bike twice last weekend and it ran perfectly fine...I'll learn to live with the noise because it's definitely not affecting the fun factor.

After I rode it like that, I tightened the drive chain to spec and rode it again - no difference..just had to rule that out.