Really like this farkle but .... could a straight pipe ...?

[angellr]

http://www.flickr.com/photos/10852133@N ... 652381698/

Bill's [ShinySideUp] comments to me as follows:

I didn't keep the exhaust tip on my bike for more than a month: got tired of the loud noise. Now looking how to rig up an electric exhaust cut out so I can have noise when I'm lane splitting. I didn't have any namebrand tip: just a standard chromed 12" extension, cut at a 45 degree tip, available at any muffler shop for about $10.

You may want to post the dealership comment on leaning out the fuel mixture on the forum to see what others say. I certainly don't have the knowledge to make an educated opinion. But Don E., among others, might.

To recap about the above comments ... talking to "the boys" at the local dealership on Saturday and one comment was that not having "the muffler" on the bike would cause the fuel mixture to "lean out". Anyone have any ideas?

Thanks.

[deilenberger]

To recap about the above comments ... talking to "the boys" at the local dealership on Saturday and one comment was that not having "the muffler" on the bike would cause the fuel mixture to "lean out". Anyone have any ideas?

Thanks.

I think the boys are correct. AFAIK, the ECU only goes "closed loop" (ie - mixture set by O2 sensors) under constant RPM conditions (or close to it..) On acceleration - the usual system defaults to a "map" - which controls the fuel mixture based on RPM, not on exhaust mixture readings. So.. it's possible the bike could go lean under acceleration IF the cutout improved airflow through the system.

Thing is - I doubt if it does any more then make more noise.. the usual restrictions on airflow are things like the valve sizes and opening. It doesn't cost BMW any more (or at least enough to be significant) to design an exhaust system that has adequate flow characteristics.

[TIV]

The boys at the shop are correct. No muffler = better flow. With more flow you'll need more fuel to prevent leaning it out. I doubt the computer makes up for a missing muffler. You'll probably shorten the life if not burn up your motor running like this. Most radical pipe changes require re-jetting or a remap.

P.S. Please don't ride that thing past my house. [plugs ears].

[ShinySideUp]

Funny, but the boys at MY local dealer said it wouldn't hurt anything, and wouldn't void my warranty. And before I tried replacing the muffler with a shortie tip, I read of many owner's experience in the R1150 portion of the forum who have run like this for years without a problem.

Don't forget, the catalytic converter must offer quite a bit of restriction also, since it does quiet the engine somewhat. Without data, who knows?

[sproggy]

And before I tried replacing the muffler with a shortie tip, I read of many owner's experience in the R1150 portion of the forum who have run like this for years without a problem.

It's a bit dangerous to equate the 1150 to the 1200 in this respect - the 1150 has a much cruder injection control system that runs the engine richer than the 1200, which can be held 'on the edge' in mixture terms. So on the 1150, fitting a free-flowing exhaust (e.g. a 'stubby' attached to the catalytic converter) would lean the mixture out slightly but there was enough margin for it not to matter in most cases but on the 1200 there probably isn't that margin.

Maybe warranty conditions in the US are different, but over here if you fit a road-legal (tested, stamped) aftermarket muffler your manufacturer's warranty is valid, however if you fit a non-tested, non-legal alternative (like a straight-through pipe) any engine damage that can be attributed to this will not be covered by the warranty.

The catalytic converter on the 1200 provides much less sound-deadening (so perhaps less restriction too) than the one on the 1150 - run an 1150 and a 1200 without a muffler and you'll certainly notice the difference.

[Tarmac]

You certainly are reducing back pressure, but I think you'ld be running the risk of burning an exhuast valve unless you "re-jetted" the fi with a power commander.

[celticus]

Whatever, I like the looks of it.
I was near an 1150 with a similar set up and it was not too loud. I was surprised.

Mark