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- Subject: "Tuning"
- From: "Tom Brown" <tbrown@xxxxxxxxxxx>
- Date: Wed, 9 Mar 2005 11:15:49 -0600
>"Tuning" in the acoustic sense, as Brian correctly uses the term, is when
you have a resonance which produces some useful effect (either pushes extra
mixture into the cylinders or helps extract more after combustion). As he
says, engineers use these effects typically to fill a "hole" in performance
or to add oomph somewhere in the rpm compass. Most typically, to boost the
advertized HP at peak - which tends to be useless (or worse) for street
The only "tuning" procedures I've ever recommended are
1. 0=0 to "tune out" the surge phenomonon on 1100s and non twin spark 1150s.
2. Possibly replacing the Oxygen sensor with a less sensitive one for the
3. Exchanging 1100 RS and RT intake tubes for GS tubes. This actually lowers
peak HP, but fattens up the curve where you use it and smooths out the motor a
bit as well...Increases riding pleasure. Never tried it on an S or an 1150 so
don't know if it works or not...Airbox may not be compatable on S.
4. Use of Bosch 4 conductor plugs...can't come up with the number at the
moment. I've even got these in my twin spark bike and they work great. Bikes
all seem to run smoother. They're about $5 at NAPA.
5. Setting valves VERY carefully to get clearance exactly the same on both
sides. Since there is only one FI system for both cylinders, an imbalance
here always makes "sweet spots" and "rough spots" in the RPM range. You can't
"tune" them out with the brass screws or throttle cable length, just move the
rough spots around. Only a really good valve adjustment will fix it.
6. Use a powerbox in "Control Mode" to eliminate surge and have some extra
control over the mileage/performance compromise. This, used in combination
with GS tubes will cause some pinging in certain riding conditions.
7. "Twin sparking" of 1100 and 1150 engines by San Jose BMW has got terrific
response from people who've done it. You actually get a small HP increase
and surging is gone. 1150 Twin Spark bikes are tuned even leaner for
emissions, so you loose the increased HP, but a SJ twin spark will not have