Exhaust Soot

zustation · 08-27-2008, 09:01 AM

Just wondering what the latest thoughts are on exhaust soot on the R11S? I've got considerable amounts of soot that poops out of the exhaust, and leaves black marks all over the license plate. Not a big deal as it washes right off, but seems a bit strange to me.

I found a thread here that said this was probably normal, but what causes it? Is the bike running rich, or is this because of the way the bike still burns oil?

This bike has 22000KM and has burned through about a half pint of oil in the last 500Km or so. Do you still get soot once the bike has broken in a little more and stops with oil burning?

Bob Hancock · 08-27-2008, 11:50 AM

That does sound a bit rich. Has the bike been modified any with aftermarket exhaust or chip? How do your plugs look?

mrbroek · 08-27-2008, 12:37 PM

My bike has 4,000 miles on it and it does the same thing, although I only get soot from the left side, onto the left third of the license plate. Plugs look okay, as far as I can tell. Bike is not modified at all. I sure would like to know what causes it.

Motomuffin · 08-27-2008, 01:04 PM

New here, don't mind me...

Mine's an '01 with 57K miles on it. It's always done this (OK can't say always but I've owned it since 28K miles and it's done it since then), out the port-side pipe more than the starboard (port-side comes straight(er) outta the manifold). I always chalked it up to the oil it uses: smoke --> soot. Has an aftermarket FI chip and certainly runs rich; goes through about 1/2 a quart of oil between changes.

I clean the pipes off regularly but leave the soot on my plate (stickin' it to the man!). ;-)

Guest24 · 08-27-2008, 01:49 PM

You certainlt don't wany an aircooled boxer to run lean. Do you get out on the road occassionally and run it in the 6-7k rev area? If not you need to. If you have a two into one system the left is always going to be the primary exhaust can. When the revs get up there the right takes the up the slack.

R111S · R111S's Garage

Mine makes soot too but not much on hot days and more so on colder days. There must be a temperature sensor that richens the mixture when it's cold.

Bob Hancock · 08-27-2008, 06:56 PM

Quote:

Originally Posted by Nail24

If you have a two into one system the left is always going to be the primary exhaust can. When the revs get up there the right takes the up the slack.

Not for the stock R11S system, which for some reason flows the right side (as seen from the back) first...then the left at higher rpm.

zustation · 08-28-2008, 10:31 AM

Definitely no aftermarket exhaust, and no chip that I know of, but I'm the second owner so not 100% sure.

Mine does the same thing as mrbroek's bike, lots of soot on the left third, but I assumed that's just because the pipe to that side is a straighter run to the cat.

Spoke to the dealer yesterday about it, they say this is pretty normal, and their advice was to get friendly with the rev-limiter. Sounds like a fun plan to me.

Guest24 · 08-28-2008, 12:04 PM

Quote:

Originally Posted by Bob Hancock

Not for the stock R11S system, which for some reason flows the right side (as seen from the back) first...then the left at higher rpm.

Seems like I saw a stock set of can cut open on one of these forums and one side looked like the path of least resistance then the other as exhaust volume increased just like you described Bob. That's above my fluid mechanics level.

JonyRR · 08-28-2008, 12:16 PM

Perhaps it needs a new 02 sensor.
they ARE a service item, y'know...
I just put my 3rd set in my '94 530I cage.
NAPA has a generic bosch 4-wire OEM replacement for about 1/2 the price of the OEM BMW part number.