Power Valve

I saw a brand spanking new 1200 yesterday and it was the first one I'd seen with the silver end cap on the silencer (muffler) and it presumably had no pressure operated valve fitted to it (I was following it at the time).

I don't think that it's too difficult to see what's going on here.

First get rid of the extensive toolkit and puncture repair kit.

Next only supply one real key with a new bike?

Then re-design the silencer to make it more restrictive, legal at tested rpm and cheaper.

All cost cutting measures.

The reason that some bikes presently have black ended silencers and others silver is probably due to working through the stock of black uns.

Mystery solved I suspect.

Peter
 
Interesting speculation ... but we don't know that the new silencer is "more restrictive", or that it doesn't have this pressure valve thingy designed into it in a different way.

Until someone dynos an old bike and a new bike to compare them, I guess we'll never know for sure.

Maybe BMW decided the fancy silencer was a waste of cash seeing as everyone replaces it instantly with a Remus :D
 
Mouse

The purpose behind the valve is to lead exhaust gases through a more restrictive part of the silencer until revs had risen beyond a point. The point at which I suspect noise testing is carried out (5,000 rpm?).

Then the exhaust gas pressure opens the valve and effectively de-resticts the exhaust for more torque & power.

It follows logically that if the silencer is redesigned to save money and get rid of the valve and still pass testing then the can will remain more restrictive through the rev range.

Just a thought.
 
Wraithwrider said:
...
It follows logically that if the silencer is redesigned to save money and get rid of the valve and still pass testing then the can will remain more restrictive through the rev range.

Just a thought.
Click to expand...
or less restrictive throughout the whole rev range, maybe the ones without the valve are the ones to have!
I seem to remember the original press releases saying the zorst had been tuned for pleassing but legal noise, maybe thats the purpose of the valve but as the thing is so quiet they've decided not to bother.
Alternatively maybe we don't have a clue and should be out there giving it some stick.
Cheers JG
 
Wraithwrider said:
Mouse

The purpose behind the valve is to lead exhaust gases through a more restrictive part of the silencer until revs had risen beyond a point. The point at which I suspect noise testing is carried out (5,000 rpm?).

Then the exhaust gas pressure opens the valve and effectively de-resticts the exhaust for more torque & power.

It follows logically that if the silencer is redesigned to save money and get rid of the valve and still pass testing then the can will remain more restrictive through the rev range.

Just a thought.
Click to expand...

Only problem is I think the "valve" is operating at 2000 rpm plus as I noticed it when running in. Probably the noise tests are carried out at constant speed = no accelerating which means it's nice and quiet? Maybe this is how Ducati and HD get their bikes sounding a lot noiseier than the rest?
 
I had one, but cut it off and welded the little hole shut. No clue what its for.
I did some more mods on my exhaust (its now an inch and a half shorter) and makes a lof of noise now. Have to re-open the exhaust again since I found the sound a bit to obstrusive.

The bike does pick up a lot better though :D
 
John Armstrong said:
Only problem is I think the "valve" is operating at 2000 rpm plus as I noticed it when running in. Probably the noise tests are carried out at constant speed = no accelerating which means it's nice and quiet? Maybe this is how Ducati and HD get their bikes sounding a lot noiseier than the rest?
Click to expand...

FWIW the manual states the following:

Ride past test to EU spec 79dB

Stationary to EU spec 87 dB at 3,500 rpm

Andres
 
Omega said:
I had one, but cut it off and welded the little hole shut. No clue what its for...
Click to expand...

Wow! Anyone else find this statement interesting? "No clue what its for so I cut it off and welded it shut!"

Truly amazing!

JQ
 
Yes I have to agree.

If it stops the valve working it will stop the designed de-restriction at higher revs.

Really clever:D :D
 
Obviously has a dyno and more experience than Remus / Scorpion / Akrapovich etc. Wonder how much he'd charge to rewire my bike.:D Using an electric welder to test what's live and what isn't.:eek:
 
JollyQuick said:
Wow! Anyone else find this statement interesting? "No clue what its for so I cut it off and welded it shut!"

Truly amazing!

JQ
Click to expand...

Its the post of the year so far...love it :D

More please, more.....
 
Hi folks, I must give you some info concerning my bike delivered to Sweden

Mine ordered months ago, picked up 22/March and it's 05 production line.

I have the black end , and THINGY...

The R12s delivered to this country all have them because we will not accept the slower low budget version of the bike.
If you have problems with having the slower version Im sure you can order the Power Valve device from your dealer.

It will increase power by 20-25% depending on temperature, humidity etc.

and I have the added pleasure of the lightweight magnesium toolkit too...

Keje/Sweden
 
Aaaggghhhh guys it's just an exhaust its no rocket sience :rolleyes: :D
Its a dead-end thinghie, had a tiny little hole in the middle, so what (good) can it do??

Anyway the exhaust is under construction because it was to loud (sounded almost like a Ducati with open pipes ;) ) Probably gonna shorten it a bit more and put back some sound dampening stuff.

No worries I'll let you know the result.
 
BMW Official Response

I took my 05 GS12 in for it's post run-in service today, (silver end, no thingy) and when i asked if they were aware of the difference, and indeed what the "thingy" is for.... the response.........

"The older versions have the black end and thingy.... but don't know what it did, or why it was changed"

and that came from the head of the service dept.....

nice to see even the dealers are clueless on this one !!!!!

:D
 
Power Valve - How it really works

724.jpg


Top Secret internal BMW document found
Keje
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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