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Turbocharged, Supercharged, and Hotrod Motorcycles: [turbobike] BMW question

[turbobike] BMW question

Gregor Halenda (gregorhalenda@yahoo.com)
Mon, 15 Jun 1998 21:01:03 -0700 (PDT)

All right, this isn't a GSXR question but engines are engines and
turbos are turbos so I'm sure this list can be helpful. First some

I have a 1985 BMW K100RS with a kit manufactured by RB Racing and sold
by Luftmeister (both of California). It's a fairly well sorted system.
The bike has an intercooler and nonvariable boost set at about 8lbs
for (I'm told) about 150hp at the rear wheel. Luftmeister has gone on
to bigger and british things and isn't very interested in helping
someone with a 10year old kit on their bike. RB Racing is nice but
they just aren't helpful - I'm always getting the "Let me get your
number" routine. I bought the bike used and it has about 40,000 miles
- at least half of it with the turbo I'm guessing as I don't know any
history for the first 20k.

The bike runs strong but as I become less fearful of the boost I'm
finding that the engine won't run clean in first or second gear. In
first it's a bit slow to get going (no poppet valve) and when boost
hits at 5000 it rockets really hard but then starts to miss and cut
out at 7000-8500 (redline). Once you shift your back in the low boost
and it's great until 7500-8000 or so and the same thing happens again.
In third it's great and 4th and 5th are fine as well. I believe (but
have no way of knowing) that these bikes had different chips put in
for the mapping of the injection (they'd have to wouldn't they?) but I
don't know. I also don't think that this was a problem when I got the
bike but I can't be sure as I generally didn't wind it up in first or
second as the thought of wheelie-ing a big sport tourer over was (is)
a bit scary. I'm starting to enjoy the power wheelies and would love
to solve this.

Could it be old injectors? Could new (different) ones help? Not enough
fuel pressure? Clogged fuel filter? It seems to do with the _rate_ of
acceleration rather than with rpms alone.

My mechanic rode it, got it up to 160mph, out ran a cop and loved the
bike but had no real thoughts on the matter.

Ideas anyone?

Gregor Halenda
Team Incomplet - NYC

"Everyone that goes faster than you is an idiot
and everyone that goes slower than you is a jerk"

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