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- From: "Tom Brown" <tbrown@xxxxxxxxxxx>
- Date: Tue, 29 Apr 2008 18:49:06 -0500
- Subject: Throttle Surge
As far as removing the cat, there is nothing that will hurt the bike and all
is reversible. The problems come in when you do things that can damage the
cat, like try to unplug things and leave the cat on. I would not, for
instance, pull the Cat Code Plug for more than a couple days with the cat
still installed on the bike. As I say, I have a friend that rides over 50K
per year who lives in Scottsdale, AZ. He loved his black 2000 RT with Remus
and cat code plug pulled. No Techlusion Fuel Nanny. I rode this bike and
it was stellar. He had an off with it and had to replace it. He couldn't
find anything he liked better for the price so he both another low mileage
black 2000 RT and put all his accessories on it. He was good for another
100,000 miles or more. As far as I know, he's still riding this bike all
across the western states whenever he can. I don't know what sort of fuel
mileage he gets, I imagine it's not as good as a stock bike, but he doesn't
care. The sound was terrific; just right; thoaty but not too loud. If you
want to pull the cat, I think this is a good way to go.
With the cat still in, the Techlusion solution was used by me successfully.
I did not set the thing for performance and it did not run much richer than
the stock setup. It ran at least as well as a stock bike but was smooth
running in the critical RPM zones that the stock bike was not.
It's not good to run it too rich for too long with the cat installed. That
is what can damage the cat. Don't run your bike with the cat code plug
pulled and the cat still installed. Some people do, but it's hard on the
cats and they're expensive to replace. You may not ever want it again, but
I've sold off both of my Techlusion boxes, but I can tell you that they are
fairly simple devices. It has a small circuit board in a plastic box with
three adjustable trim pots on the board. They are adjusted with a small
screwdriver. One is the high speed adjustment. One is the low speed
adjustment and one is the crossover point between high speed and low speed,
if I remember right. There are no batteries. It's powered by the low
voltage that triggers the FI nozzle. You hook it up to ground and to one
of the FI nozzle leads on the left side of the bike. There are two modes
for this unit. The first mode is useless. The one that works requires that
you unhook the oxygen sensor and make a jumper to jump two of the leads in
the cat code box under the seat after you remove the cat code plug.. This
is easily done and explained on the website. The setting of the pots is
also explained. I found that the bike worked best with the pots set very
near the recommended settings. I would start there. If it still runs
lumpy, add a 1/8 turn to the direction of rich on the low speed setting.
If it runs OK, turn it a tiny bit leaner and keep trying until you get bad
running then set the pot back to the leanest point where it runs well.
This will cure surging definitely because it disables the feedback loop in
the fuel injection that causes it.
The device works in this way: Replacing the cat code plug with the jumper
gives the fuel injection a consistent and very lean fuel map. Unhooking
the oxygen sensor is necessary for this fuel map to work right. With these
two changes, you create a "blank slate" for the Techlusion box to do its
stuff. It works by adding time to the "on" cycles of the FI nozzle. So,
first you take fuel away, then you set the box to add it in the way that
suits the bike best. If you add a lot, you can get increased performance,
but at a cost of dirty running and high fuel consumption. This isn't good
for the cat either. It's fun to try for a short period just to see what
the bike will do if economy and clean were not part of BMWs goals, but this
setup just isn't right for the long haul.
If you don't want to fool with either of these things, I found that 1100GS
intake tubes, which can be purchased from BMW inexpensively, help smooth out
the bike in the "surge zone". I've installed these on many Oilheads and
everyone likes them better. Fuel mileage actually goes up a bit. The only
cost is a drop in ultimate HP at near redline. Most of what we use an RT
for is better with these tubes, surging or not. It also happens to soften
the annoyance level of surging. There are some alignment marks on these
tubes and they must match up with the lines on the throttle bodies or the
bike will never run right. Even a quarter inch on one side makes a big
difference. It's just a matter of loosening the hose clamps and twisting
the tubes until they line up.
Setting up the throttle bodies and careful, accurate valve adjustment also
helps a lot.
There is a procedure described in www.ibmwr.org <http://www.ibmwr.org/> for
setting throttle bodies up. It's called "Zero Equals Zero". It's also
All this stuff helps. If you set up the Techlusion for the leanest good
running setting you can find, you'll see that the economy is very near the
same as stock.
If you go the Techlusion route, I wouldn't put on the GS tubes. I got
pinging in hot weather passing type situations with that combination.