O.S. Engines 61VF - Manual

O.S. MAX-61VF
INSTRUCTIONS FOR O.S. MAX 61 VF ENGINE
The O.S. MAX-61 VF is a high performance engine that has been
developed expressly for FAI type R/C contest models. It em-
ploys schnuerle scavenging and a rear exhaust port to facilitate
the installation of a tuned silencer system, especially where the
latter is to be built into the fuselage.
This engine features specially developed ABC type piston/
cylinder construction and a 17 mm O.D. crankshaft of heavy
duty alloy steel in order to provide extra power and durability
and is equipped with an O.S. Type 7D carburettor, specially
designed to give good throttle response.
Modern precision machinery and carefully selected top-quality
materials are employed in the manufacture of this engine to
ensure consistent performance and long life.
SPECIFICATIONS
Displacement
Bore
Stroke
Practical R.P.M.
Power output
Weight
9.95 c.c. (.607 cu. in.)
24.0 m.m. (.945 in.) /
22.0m.m. (.866 in.)
2,000 ~ 17,000 r.p.m.)
1.8 PS (17,000 r.p.m.)
528 g (18.6oz.)
INSTALLATION
Mount the engine securely on rigid hardwood mounts or metal
bearers. For highest performance and safe running, we recom-
mend that the bearers should be as heavy and as rigid as possible.
Make sure the engine bearers are parallel and their mounting
surfaces are in the same plane. Use 4 m.m. or 6—32 steel screws,
such as Alien type, with locknuts, for bolting the engine to the
bearers.
RUNNING-IN ("Breaking-in")
The special ABC type piston/cylinder construction, two ball
bearings, bronze bushed connecting rod, etc., enables this engine
to be operated after a shorter running in period. Preliminary
bench running can be omitted. However, for long life and peak
performance please observe the following procedure:
Install the engine in your model and fly it with a rich needle-
valve setting so that it runs at a fast '4 stroke' for the first two or
three flights. Then readjust the needle valve for a slightly less
rich mixture (i.e. at a reduced speed '2-stroke') for the next four
to six flights.
FUEL
Use a good quality commercial fuel or one of the fuels shown in
the table. "A" is suitable for general use. If higher output is
required, fuels containing 10 to 20% of nitro methane; (e.g."B")
may be used after running in.
Lubricants can be either castor oil or synthetics provided that
they are always of the best quality.
Methanol
Castor Oil
Nitromethane
A
77%
23%
-
B
57%
23%
20%