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

RE: [turbobike] BMW question

PELLEGRINI (hjcp@ba.net)
Wed, 17 Jun 1998 23:42:27 -0300

-----Mensaje original-----
De: Robert Miles <rmzalbar@hotmail.com>
Para: gregorhalenda@yahoo.com <gregorhalenda@yahoo.com>;
turbobike@natvideo.com <turbobike@natvideo.com>
Fecha: Martes 16 de Junio de 1998 16:09 PM
Asunto: Re: [turbobike] BMW question

>Hi Gregor,
>I would guess that what you are having is an ignition misfire rather
>than a fuel delivery problem.  First look at your plugs.  If you are
>running lean, you will see signs of detonation on the plugs (rounded
>electrodes, little black specks on the center ceramic insulator) as you
>go lean under boost.  Ignition misfire seems more likely from your
>symptoms.  It's harder to put a spark through the denser air/fuel
>mixture that you get when you load up the throttle and generate high
>boost, and as your RPMs climb the coils have less time to recharge
>between firings, exacerbating the problem.  (Rob loses a coolness point
>for frivolous use of "exacerbating.")  An weakening ignition system that
>does fine under normal conditions can begin to experience problems when
>put under such loads as a boosted air/fuel charge.  You may have a weak
>coil or a leak to ground through a bad plug wire.  If your bike has a
>breaker point system, check out the points, dwell, etc. as well.  Bad
>points can cause a weak spark too.  Another cause might be a short in
>the electrical system that grounds out intermittently when the bike is
>thrust forward by acceleration, but I think weak ignition is your
>answer.  Hope this helps some.  Good luck!
>-Rob Miles
>'73 CB750K
>'85 Dodge Omni GLH Turbo
>Wish I had a turbo BIKE!
>>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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