Subject: Metering pump
From: ACRE
Date: 8/4/2004, 9:16 AM

Does it come out of the air supply line as well or are there two one
way valves in there?

Paul Lamar


Hans Conser wrote:

There is  a check valve built into the injectors themselves.  You can
clean them by blowing air from the oil line attachment side, but it
wont go the other way.

Hans

I am pretty sure it is not there Bill. The shop manual says nothing
about checking it.

Paul Lamar


Paul,
If you check the Oil Feed Line at the banjo fitting I am almost
certain that you will find a small check valve. It has a very low
break-away pressure of about
2-3psi. This was used in all the motorcycles very effectivly. It
would also prevent the chamber pressure from backing the line up. The
check valve doesn't
have to be built into the pump itself. This system was used in piston
engines in the intake tract so it had to deal with pressure reversals
there too.
Bill Jepson

Al Gietzen wrote:

OK; I have studied the diagram of the metering pump, and I'm pretty
sure I
understand how it works.  It meters and pumps; it is essentially a
positive
displacement pump.  The pumping results from the vertical motion of
the
shaft.  No check valves necessary because the inlet port is closed
by
the
shaft as the shaft drops and forces oil out the outlet.  New oil is
drawn in
as the shaft rises while the outlet port is closed.

The flow adjustment lever determines the amount of up and down
travel
of the
shaft by varying the space between the stop pin and the adjusting
pin,
which
determines the vertical movement driven by the wobble plate.  Rather
clever,
really.

My conclusion is that it is altitude independent.

Al

No check valves Bill. It is a piston ported pump something like the
old
Bristol sleeve valve radial engines. I still think it is
possible. Also most the more recent engines had some sort of air
pressure assist on the apex seal oil nozzles.

Paul Lamar

 
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