Exhaust system change on a new RS

[mikefoto]

I am picking up a new 1200RS, and on one of these forums I think I read that it was worth it to get rid of the stock exhaust, to save weight (40lbs) or so, maybe slight improvment in performance. The dealer agrees and said it would cost around 1K. Does that seem right and is it REALLY worth doing? Thanks for any opinions for a new bmw owner.

[MarkF]

That sounds about right for a staintune exhaust. Probable one of the best made aftermarket pipes. You can probably get something else, like a Two Bros. or Remus for less but they will require repacking eventually and don't have the same level fit and finish. My $0.02! But I'm only a K-bike observer.

MarkF

[pdbiker]

You'll probably get all kinds of replies stating that the new pipe will give you all kinds of power but don't believe it. I changed mine to a Two Brothers for the simple reason that I wanted a better sound. It gives a 14 hp increase at redline. The only problem is that I don't spend a lot of time in that range. The sound improvement, however, is worth it in my estimation. I've had the Two Brothers on the bike for approx. 30K miles and it probably should be repacked but it sounds too nice and I wouldn't think of messing it up until it hurts my ears.

Just my $.02

[AntonLargiader]

Golly, all of these exhaust threads.

I'd be surprised if the difference between the stock system and an aftermarket system was 40 pounds. The parts fiche only thinks the entire exhaust weighs about 25 pounds.

Folks on the GS list are finding that their Two Brothers systems need repacking with annoying regularity. That is, if they don't wait "until it hurts their ears."

Sheesh. Forget about other people's ears.

[RebeccaV]

Congrats on your new RS, mikefoto (we want to see pictures!!). When you say 'worth doing' does that mean that the dealer is trying to push the aftermarket pipes? I guess that I'd be suspicious of that.

What sort of improvement in performance do they claim? I've never heard that about an aftermarket exhasut. Does anyone have any info?

[deilenberger]

Originally posted by mikefoto
I am picking up a new 1200RS, and on one of these forums I think I read that it was worth it to get rid of the stock exhaust, to save weight (40lbs) or so, maybe slight improvment in performance. The dealer agrees and said it would cost around 1K. Does that seem right and is it REALLY worth doing? Thanks for any opinions for a new bmw owner.

OK.. let's see:

1. You haven't gotten the bike yet?

2. You have reached the limits of the factory performance?

3. The dealer wants to sell you an accessory for a bike you haven't gotten yet and don't know the limits of?

If I have that all clear.. my question back to you is..

WHY?

The only way to save 40lbs is to do away with the exhaust. In testing I've done on other K models - I've found no free lunch as far as exhaust systems - which means, no OVERALL power increase. I have seen some systems that peak out the HP at max RPM and add a few HP - but I have not tested a system that gives an overall improvement in HP (like where it's useable.) Frequently this extra few HP at max RPM comes at the expense of useable HP at useable RPM's. To my mind - that's a no brainer, all you've bought is some dubious bragging rights.

Most people I know find the K1200RS has "adequate" power to garner them lots of speeding tickets without any effort at all. I know a number of people (good riders too..) who have sold their RS's to lessen the number of tickets they were receiving.

My suggestion - ride the bike AS it comes from the factory, and only then - if you really feel the need for more power - consider some aftermarket components. IMHO - just doing the exhaust will gain you very little - and the most significant lightening will be in your wallet.

But thats just me.. YMMV as usual.

[davel]

Originally posted by deilenberger
My suggestion - ride the bike AS it comes from the factory, and only then - if you really feel the need for more power - consider some aftermarket components. IMHO - just doing the exhaust will gain you very little - and the most significant lightening will be in your wallet. I agree, 40lbs isn't going to make that much of a diffrence on a bike as heavy as the RS anyway (so now it weighs 650lbs?), and any performance gain will be minimum compared to the cost (5hp for $1k), if your looking for a better sound you can spend less and get that, but I would recommend buying more functional things: SS brake lines, wider rear wheel, even NOS or turbo if you want to really go fast!:clap Good Luck!

[drmajor]

Two Brothers is typically the loudest and does need repacking.

A friend has a 2001 KRS with Remus. wonderfull sound. can't say what it did for hp, as it came with it. It is not loud, but sounds like 1/2 of F1 car.

I think Staintune is very similar to Remus in sound and quality.

[davel]

I ran across this article in my archives, this was from a company that was trying to develop an exhaust for the K-bikes "independent dyno testing seems to show that after market mufflers actually rob k bikes of power, similarly the stock airfilter seems to do the best job of filtering the air and even half blocked by tape has no effect on output power" :dunno

[deilenberger]

Originally posted by davel
I ran across this article in my archives, this was from a company that was trying to develop an exhaust for the K-bikes "independent dyno testing seems to show that after market mufflers actually rob k bikes of power, similarly the stock airfilter seems to do the best job of filtering the air and even half blocked by tape has no effect on output power" :dunno

Nice to see my dyno runs get some credit :D

That's about an exact quote from my conclusions after running lots of K bike dyno runs - and wrapping the stock filter in SaranWrap(tm)(reg.us.pat.off).

It's hard to beat the stock stuff. IMHO - BMW doesn't leave a lot of horsepower laying on the table for some garage hack with a welder to find and plug back in. BMW has the knowledge, experience and testing facilities to maximize performance. The name of the company is Bavian MOTOR Works - and they take a lot of pride in getting the most power out of any engine they make (good article in the BMW company magazine about some new cage engines they've designed - and how their I-6 car engines have won "Best Engine" awards for the past 10 years).

Not to say that someone can't get a HP or two more at some specific RPM, but I have yet to see a system that did that without loosing power someplace else - usually power in a useful RPM range.

FWIW - Motorcycle Consumer News - a number of years ago did a series of dyno tests on replacement exhaust systems for the Honda Goldwing. From memory - they tested about 15 of them. Only ONE made the same power as the stock exhaust. ALL of the other ones lost power. I think Honda must do a pretty good job also.

Most reputable K bike performance people will tell you that it isn't the air filter or exhaust that is the limiting factor on K engines. It's the valve size, and perhaps the camshaft used to make the bike rideable. My K75S had the head ported/polished, oversize intake valves installed and most of the other go-fast tricks done to it by the former owner. In testing I've done - it makes the same power as a K75 with over 100k miles on it. The one with all the miles on it did have the timing advanced a bit (see the IBMWR K-tech FAQs on how to do this..) I haven't gotten around to doing that on mine. That is the cheap way to pick up power on a K engine. The only downside is - the engine will not be tolerant of below-grade fuel. I normally run premium, so I don't see that as a problem.

No free lunch.. especially when it comes to exhaust systems.

BTW - looking for some later model K's to do dyno runs on - especially where the owner has an aftermarket exhaust and the stock exhaust, and can get it to NJ where the dyno is. The runs will be free if that's an incentive :)

Best,