R1100s stock exhaust crossover pipe baffled...

Ronwash80 · Post by **Ronwash80** » Wed Sep 04, 2013 10:38 pm

Hey everybody,
I'm new to this forum but let me say that I'm extremely relieved to find a forum dedicated to r1100s. I just baught a 2001 r1100s back in march of this year and all ready I'm in love with this bike and the Beemer family of riders! This is my second Moto, the first being a 2006 Buell lightning XB 1200s. The Buell was a fun bike but i just found it to be a pain to maintenance myself ( an awesome perk of the ol oil head ).

So last week I decided to go through the bike and really start to clean her up. I painted to front forks the telelever bottom support all of the Allen screws to whole front end and wind screen. Now I'm working on the pipes, I've repolished them ( they came out way better than expected ) but I still need to paint the part that bolts to the cylinder head.

Here's where I get confused, while polishing the right side manifold I notice the baffle in the crossover pipe. The baffle clogs up must of the pipe except for 10 mm of it. Why is this? Wouldn't the bike run better with out it? Is this just something BMW did to the bikes they sent over here to the states? The bike is mostly stock with the exception of a k&n air filter, cat eliminator pipe and a set of two brothers racing c2 cans. If I reamed out part of or all of the baffle would that ontop of the other mods to the bike too much for a stock ecu to handle?

Thanks!

Al · Post by Al » Wed Sep 04, 2013 10:54 pm

Hi and welcome, can`t help with your query but I`m sure someone else will be along to help, there is also a forum for 11/12`s your side of the water, try putting pelican r1100s forum into google, a few people on here also post on pelican.

Al.

Ronwash80 · Post by **Ronwash80** » Thu Sep 05, 2013 1:56 am

Thanks Al,
I've been trying to register with pelican but with no successes. Pelican's website seems to be acting up today. Any ways thanks again for the info I'll try again tomorrow.

Boxadog 2000 · Post by **Boxadog 2000** » Thu Sep 05, 2013 5:54 pm

It's something to do with resonance and pulsing

Ronwash80 · Post by **Ronwash80** » Thu Sep 05, 2013 6:39 pm

I just read a post of a gentleman on another forum ( Pelican parts of which I just registered to ) who had the same question i had about the baffle in the crossover pipe.

A long story short, remove the baffle & gain a little low end grunt but lose top end power. If you seal the baffle / remove the crossover pipe you gain more top end power but lose low end grunt. Best thing to do just not to mess with it unless you absolutely have to have more low / top power with the sacrifice of opposite of what you want to gain.

exoticices · Post by **exoticices** » Fri Sep 06, 2013 11:24 am

This is from vague and aged memory so may be completely wrong but I seem to recall from the Pelican forum that the crossover pipe had a baffle fitted for (some/all) US states. The baffle was for draconian emissions laws. Removing it is a good thing.

As for the crossover (baffled or otherwise), there was an agressive difference of opinion as to whether it's good or bad. I think the consensus for most 'normal' people was that it's not worth worrying about unless you want to go racing.

As I said, all this is from memory, so please double-check it on Pelican before taking a dremel to your crossover baffle!

Also, as you're in emissions-third-reich California, you might have problems with your equivalent of the MOT test if you remove an emissions baffle?

Post a pic of your Buell in the 'my other bike's...' section. They are nice but as you say, Erik seems to enjoy only 70% developing a bike then leaving the remaining 30% for the owners to sort out!

buzzz90 · Post by **buzzz90** » Fri Sep 06, 2013 2:28 pm

If the Cat is already removed, my guess is, that emission level is not his top concern...

exoticices · Post by **exoticices** » Sun Sep 08, 2013 8:28 pm

buzzz90 wrote:If the Cat is already removed, my guess is, that emission level is not his top concern...

Quite right. I couldn't give a hoot about 'emissions' neither. Another con for back-door tax. I was just concerned as my only knowledge of Californian politics is from Dead Kennedys records.

I couldn't resist looking further into this baffle business (I have no social life). It seems to be a common boxer theme, even older stuff like R90s, but there seems no clear reason why (or even if) a baffle is fitted in the crossover. BM don't list it on parts fiches for example. It doesn't seem to be an emissions thing as my weak memory originally thought.

The upshot from what I've read seems to be that the baffle doesn't do any harm but a free-flowing system is generally 'better' than one with baffles and other obstructions.

Anyway, I hope it helps the OP though I fear I've just added more confusion, sorry!

Corvus · Post by **Corvus** » Mon Sep 09, 2013 8:31 am

It begs the question what is the purpose(s) of the crossover pipe?

It is an enigma wrapped up in a mystery. I have a vague recollection of reading about it in the late seventies. That vague recollection is that they help cylinder filling at low rpm on engines with long valve timing/overlap. True?

If that is the main reason, I can imagine that they will (only?) work on certain engine types or cylinder matches. ie: 360 degree twins or each pairing thereof. True?

I can imagine that, maybe as a secondary bonus (if you look at it as a bonus!), they may make for a quieter exhaust?

You stand and look at a motorcycle and think "yeah, simple bit o kit that. A pushbike wi an engine." But it seems not to be the case!

Ronwash80 · Post by **Ronwash80** » Mon Sep 09, 2013 6:24 pm

exoticices wrote:
Also, as you're in emissions-third-reich California, you might have problems with your equivalent of the MOT test if you remove an emissions baffle?

Post a pic of your Buell in the 'my other bike's...' section. They are nice but as you say, Erik seems to enjoy only 70% developing a bike then leaving the remaining 30% for the owners to sort out!

You know as crazy as this sounds but I don't think you actually have to do an emission test on you Moto here in emissions-third-reich California haha, I never have.

I'll post a pic of the Buell after my reply to this.

conkerman · Post by **conkerman** » Mon Sep 09, 2013 8:10 pm

I'd have thpught CARB would habe a shit fit if they found people messing with emissions control systems.

Used to deal with them in my old job . A funny bunch.

Ronwash80 · Post by **Ronwash80** » Mon Sep 09, 2013 8:25 pm

exoticices wrote:
buzzz90 wrote:If the Cat is already removed, my guess is, that emission level is not his top concern...
Quite right. I couldn't give a hoot about 'emissions' neither. Another con for back-door tax. I was just concerned as my only knowledge of Californian politics is from Dead Kennedys records.

I couldn't resist looking further into this baffle business (I have no social life). It seems to be a common boxer theme, even older stuff like R90s, but there seems no clear reason why (or even if) a baffle is fitted in the crossover. BM don't list it on parts fiches for example. It doesn't seem to be an emissions thing as my weak memory originally thought.

The upshot from what I've read seems to be that the baffle doesn't do any harm but a free-flowing system is generally 'better' than one with baffles and other obstructions.

Anyway, I hope it helps the OP though I fear I've just added more confusion, sorry!

So from what I read, and i'm trying to keep this short so as to not write an entire novel here.

Cross over pipes are designed to scavenge exhaust from the other cylinder (there is a whole article floating around on the web about exhaust scavaging if anybody has any questions). BMW was able to draw the big power increase on the 11S (over the earlier R, RS or RT models) via mods in the exhaust system- they probably did pretty extensive research on this aspect. My guess is that baffle is one of those mods.

Another article stated that removing the baffle on the cross over pipe (creating a free flowing system) is indeed good but only for bottom end (low rpm) power, the 11s actualy looses its top end power when that baffle is removed.

All that being said I've just decided to leave it alive I want more power top and bottom end not just one wit the sacrifice of losing the other. The only reason I considered altering the exhaust is be uses it was free.

Ronwash80 · Post by **Ronwash80** » Mon Sep 09, 2013 9:08 pm

Corvus wrote:It begs the question what is the purpose(s) of the crossover pipe?

It is an enigma wrapped up in a mystery. I have a vague recollection of reading about it in the late seventies. That vague recollection is that they help cylinder filling at low rpm on engines with long valve timing/overlap. True?

If that is the main reason, I can imagine that they will (only?) work on certain engine types or cylinder matches. ie: 360 degree twins or each pairing thereof. True?

I can imagine that, maybe as a secondary bonus (if you look at it as a bonus!), they may make for a quieter exhaust?

You stand and look at a motorcycle and think "yeah, simple bit o kit that. A pushbike wi an engine." But it seems not to be the case!

I believe you are right on all accounts except for the part about making the exhaust quieter, I not to sure about that one...

Ronwash80 · Post by **Ronwash80** » Mon Sep 09, 2013 9:23 pm

conkerman wrote:I'd have thpught CARB would habe a shit fit if they found people messing with emissions control systems.

Used to deal with them in my old job . A funny bunch.

Oh they do, but they don't mess with the two wheel community a whole lot. But the poor folks with 4 wheels +, well that's a different story.