BMW R850 Maintenance Manual page 89

My take, after an initial 500 miles of testing...
Plusses:
- Improved roll-on power.
- Engine revs more quickly.
- Bike accelerates in the next higher gear almost like it did with the RS
manifolds in the next lower gear.
- Overall gearing now seems "shorter" (lower) when matched with the
increased low RPM torque.
- Average power delivery is smoother and stronger from idle to red line.
Marginally less fuel consumption (at steady speeds).
-
- The bike is easier to ride!
Minuses:
- Increased intake noise (honk) from the longer length tubes. (resonance). GS
riders won't notice this since it must be identical to GSs.
- Top end is reduced by about 4 MPH.
- Acceleration from 6500 RPM in 5
levels.
But wait, the story is not over! If the GS intake manifolds worked so well, how
effectively would fuel injection reprogramming optimize the system even more?
Having experimented with the Motronic fuel injection on my RS, I knew there
were six different "maps" stored in the computer which are activated by different
"Cat Code Plugs." So, to complete the GS intake "clothes" makeover, I replaced
the RS yellow Cat Code Plug with the GS pink unit. This connects different
coding plug terminals and activates the GS map instead of the RS'. The coding
plug is located in the electrical box under the seat, one row forward of the fuses.
Look in your owner's manual for reference. If you replace (or even temporarily
remove) the coding plug, you should uninstall the 5
bay for a few seconds and then reinstall it to reset the injection memory and clear
any "faults."
Part number and cost for the GS Cat Code Plug is:
61 36 8 366 625
So, how did BOTH the GS manifolds and coding plug, all for ONLY $39.38, work
in my RS? To find out I went on a 580 mile loop from Tucson through the
Arizona high country, a varied ride that encompassed Tucson's 2600 feet altitude
all the way to the "Rim Country" at 9200 feet. This route is along the famous
"Coronado Trail", US 191 (formerly US 666), and it was a superb workout of low
and high speed cornering, accelerating, and trailing throttle, especially coming
back home to Tucson through the Salt River Canyon. Verdict?
th
gear to top speed is reduced from RS
$5.99
89
th
fuse from the left of the fuse