Flappy valve renovation.

[comberjohn]

I know, I know, but I like them.
Mine had turned 40k and suspected that the flappy wasn't playing. I've taken it out and replaced with the piece of stainless and found that it was a bit stiff.
I've sprayed plenty of WD40 around the pivot points but it's not helping. It looks like it's not designed to be taken apart, but maybe someone knows better?

 

[UturnTony]

Not worth the hassle, bin it

 

[jratthews]

Hi.
As you have got the valve off the bike soak it in diesel overnight then spend 20 minutes working it open and closed and side to side to free it. It's a bit hard on your fingers but quite cheap. Then use thin silicone grease on the pivots and generously around the spring. This has kept mine working for over 10000 miles. I just check it occasionally and add more grease.


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[NZRalphy]

Bin it you will never fix it

 

[Pukmeister]

You could try oven cleaner gel like "oven pride" or similar.. We used a commercial catering industrial strength gel stolen off the cooks to clean deltic exhaust flaps on minesweepers, it used to shift the baked on carbon crud if left overnight.

For lubrication you need a nickel antiseize grease (not copper based stuff). Its what I use for the exup valve on the R1, you can buy small tins of it on eBay.

 

[comberjohn]

Hadn't thought of oven cleaner.
Main problem appears to be getting lubrication around the pivot points as they just seem to be pressed in. Guessing BMW didn't make them to last that long, just enough to get it through emissions.
I know I might have to bin it, but I like the split personality it gives the exhaust and it is a clever idea.
Think I'll try the oven cleaner and then soak it in diesel for a while. It's not completely seized, just a bit stiff.
If I have to do this every year, I can work with that.

 

[jratthews]

I think that the problem with mine was corrosion in the upper pivot. Once freed, lubrication with silicone grease which withstands high temperatures and is very runny, keeps it all working for several thousand miles. Then do it again as necessary.


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[GrinningGSer]

Well, I don't have a problem with my flap (so far), but prefer to take preventive action. I have copper grease in the garage and reading about it, I reckon its just about Ok. In all of these greases, the grease evaporates pretty damn quickly in an exhaust and it's the particles left behind, which matter (copper or nickel) and these particles act as a buffer to prevent the metals seizing together,
So, three small torx bolts and heat shield off
One exhaust clamp bolt removed and clamp wiggled loose
One torx, back-box hanger bolt removed
Wiggle the back box away and its off in the same time that I took to type this:

It's such an easy 30 min job, that it'll be on my annual list of things to do.
I also removed two small torx screws, so as to remove the plastic cap, which covers the rotating sping so as to grease from above (In the hope that all will seep downwards

Inside the pipe, you can now see the troublesome flap:

Lube with copper grease, or perhaps better nickel grease
Reports are that this flap fails by seizing OPEN, so doesn't affect running
Lube the joints for easy assembly/removal and happy motorcycling.

 

[Wreford Miles]

I thought mine had sized the other day but on inspection it was free'er than a free thing...

30,000 miles and all I've done is the occasional spray with 365, well that and It's rare that the bike has ever gone few days without being used - I think regular use and not much cleaning is the best preventative maintenance for a GS

 

[GrinningGSer]

Mine doesn't get much cleaning either, as you can probably see, but it's permanently soaked in ACF50

 

[Bendy toy]

I have the shotgun silencers. A flap valve to close one outlet would be great for reducing noise around town.

 

[Pukmeister]

I would not advocate using a copper based anti-seize on an exhaust flap, in most cases the oil burns off leaving a hard dry copper cake behind which serves to clog things up. Nickel based greases stay plastic and flow under extreme temperatures, a much better solution to the problem.

 

[comberjohn]

I have the shotgun silencers. A flap valve to close one outlet would be great for reducing noise around town.

That's exactly the reason why I like the flappy valve. Quiet around town or for pootling about and when you give it some stick, then you get the exhaust note!

Think I'll try the oven cleaner and then a diesel soak. There does seem to be a bit of carbon build up, certainly not as clean as pics above. Then I'll try and get some lube into the pivots.
Agree, regular use is good and feel that it had only recently started to stick after 40k miles.

 

[Bendy toy]

Mine isn't bad but if I wind it open to pop past a ditherer the noise is too much and makes it look like I'm trying bully them out of the way.
To be fair I'd love to do that but realise they are people inside the road blocking Korean tin box.

I bunged up one outlet & found the noise volume was reduced much more than expected. I suspect the noise bounces internally between the two cans.

A valve on the outlet runs cold so should be reliable.

Another one day maybe never idea.

 

[Bendy toy]

I want open or shut so a car door lock actuator might do the job

 

[comberjohn]

I've seen a 'Y' piece of exhaust advertised for car modifiers with a manually operated flap?

 

[Bendy toy]

Andy at Xtreme Stainless near Stafford would make something up for reasonable money.

 

[dementedmonkey_co_uk]

Out of interest how freely should the flap move? Got mine in diesel at the mo and while it has freed up some it still won't move on the motor/cables back on the bike. Cheers

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[comberjohn]

You should actually hear the flap moving when you first switch on the ignition. That's why I took mine off to check it, sounded like something was straining but not moving.
Yours sounds like mine. Takes quite a bit of effort to move the flap and not convinced I can save it. Not as much carbon build up as first thought, must be the pivot bearings that are seizing. Unfortunately, there doesn't seem to be any way of getting at them to clean and lube them.
Had thought of drilling a small hole in the bottom pivot bearing to see if I can get any sort of lube in there.
If it is scrap, might have a go at stripping it down completely. Nothing to lose.

 

[dementedmonkey_co_uk]

Yep mines been cleaned with oven cleaner to remove all visible carbon and soaked in diesel for a couple of days, while it now moves I'm guessing not freely enough still. As you say i guess the bearings are totally dried out. I wonder if the flap could be removed (looks like a couple of tack welds to carefully remove as well as the central screw) and the shaft turn pulled out?

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