2 Stroke Injection

[Michael T. Kasimirsky]

On Fri, 8 Nov 1996, Mike Grace wrote:

> Check out the new Bimota BB500 with the revolutionary BMW 500cc
> direct-injection 2-stroke engine.  Sport Rider mag. quoted engineers as
> saying it's as clean as a 4-stroke (as in it will pass CA M/C emissions!).
> I seem to remember it uses reed valve induction.  I wonder how they keep the
> oil in the case?

The Bimota BB500 uses an engine designed by Bimota; a first for the small
italian firm.  The design was originally to be used in Grand Prix racing,
but Bimota scrapped that idea as too costly.  It uses reed valve
induction, but the fuel is directly injected into the combustion chamber. 
The cylinder jugs have mounting bosses for injectors which pass through
the transfer ports.  The fuel is sprayed directly on the piston crown by
two injectors per cylinder.  This helps with the low speed mixture as well
as cooling the piston, which have a tendency to melt in large-bore
high-horsepower two strokes.  The fuel injectors were supplied by Weber
and were originally developed by Weber for Formula 1 racing and it's
17,000 rpm redlines.  The engine is a V-twin using two counterrotating
cranks, riding in roller bearings (I think).  Oil is pumped in very small
quantities to the bearings.  Other than the fuel injection, the engine is
basically a conventional high-horsepower two stroke.  The crankcase is
used to pump air into the cylinder, just like your typical motorcross dirt
bike.  The bike makes 110hp, weighs about 300 lb., and will be emissions
legal in all 50 states, supposedly with plenty of room to spare.  They'll
be coming to a dealer near you in 1997. 

If you haven't guessed by now, I'm a motorcycle junkie.  :-)

Michael T. Kasimirsky       ---->              mtk at tmc.astm.cmri.cmu.edu
Days:    Staff Engineer                     or mk4u at andrew.cmu.edu
         ASTM Test Monitoring Center		Phi Gamma Delta,
Nights:  1992 Suzuki GSX-R750 Pilot		NRA Life Member, AMA Member
         1991 Suzuki GSF400 Bandit Mechanic	DoD #1848