BMW R1200R R1150R/T F800 K1200R R1100R/T R1250R RnineT Message Board

Hi, Just bought an 03 Rockster two weeks ago as intend to tour more. Great bike so far but a little quiet as used to a V-max full power where I modified the exhaust to give a great sound. Has anyone modified their exhaust rather than by a Remus or similar.

http://r1150r.org/board/viewtopic.php?t ... ed+exhaust
Just don't run it with the cat eliminator. BIG loss of low end and way too loud.

Just take the exhaust can right off..and put a small tip on the cat..something like this..Easy-peasey.. ..and it only takes about 10 minutes.

DJ

Hi Robox,
Do a search here for the DJ mod. If your bike still has the cat fitted removing the silencer and fitting a small tail pipe you will get the sound you are after, this will also allow you to fit a full size left case from an RT. I have been running my bike like this for the past year with no ill effects.




http://r1150r.org/board/viewtopic.php?t ... 242a9a9a41

Hope this helps.

Hank

Thanks alot for the tip. I will give it a go

Ok, DJ and anyone else. I got a Staintune pipe and collector. The collector is a lot smaller than the original, maybe not even a real collector! Has anyone remove the silencer and stuck an end onto one of these little boxes???

You might be asking for trouble doing that because of the lack of back pressure (and it would be 'very' loud)..it might also lead to burning valves.

The staintune guys told me that their collector box was just a Y pipe with a box around it to make it look like a cat for those country's where its against the law to remove the cat.

The cat works like a big muffler...and running with just the cat should do no harm...so I've been told.

I'm also very interested in what a 'tuned length exhaust' is all about..I know with race bikes it's a big deal.

DJ

DJ Downunder wrote:You might be asking for trouble doing that because of the lack of back pressure (and it would be 'very' loud)..it might also lead to burning valves.

The staintune guys told me that their collector box was just a Y pipe with a box around it to make it look like a cat for those country's where its against the law to remove the cat.

The cat works like a big muffler...and running with just the cat should do no harm...so I've been told.

I'm also very interested in what a 'tuned length exhaust' is all about..I know with race bikes it's a big deal.

DJ

There's an "ideal" length of exhaust for a 4-stroke that means (IIRC) the power pulses bounce back to the valve and help to seal it at high revs.
unfortunately it's something in the region of 5 feet! Husquvarna used them in the '50s on their racer and it was so damned fast the ruling bodies introduced the rule about the exhaust not being allowed past the rear wheel....

http://www.classic-motorrad.de/galerie/ ... %20500.jpg

I know that back-pressure has a lot to do with low end performance. The cat must provide some, no?

Another advantage of the tip on the cat mod, is that you can fit a full size box on the left side!!