O.S. Engines 61VF User 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 employs 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
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.
fuselage.
SPECIFICATIONS
9.95
Displacement
Bore
Stroke
Practical R.P.M.
Power output
Weight
INSTALLATION
Mount the engine securely on rigid hardwood mounts or metal
bearers. For highest performance and safe running, we recommend 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 needlevalve 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.
c.c. (.607 cu.
24.0
m.m.
22.0m.m. (.866 in.)
2,000 ~ 17,000 r.p.m.)
1.8 PS (17,000 r.p.m.)
528 g (18.6oz.)
(.945
in.)
in.)
/
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%
GLOW PLUG
Since the compatibility of the glow-plug and fuel can have a considerable effect on performance and reliablity, it is suggested
that the user selects the R/C type plug found most suitable after
tests. Recommended O.S. glow-plugs are No. 8 and No. 9.
PROPELLER
Suggested propellers for pattern flying are 11 x 7-8. The
suitability of the prop. depends on the size and weight of the
model and the type of flying. Determine the best size and type
after the engine has been run in. Check the balance of propeller
before fitting it to the engine. Unbalanced propellers cause
vibration and a loss of power.
Wooden propellers are to be preferred. Some nylon propellers
are not strong enough to withstand the high power output of
this engine and a thrown blade can be very dangerous.
SILENCER
As this engine has been designed primarily for use with a tuned
length exhaust silencer system, a conventional silencer is not
supplied. Any of the tuned pipe silencers currently available for
10cc engines may be used by inserting, with the aid of silicone
tubing, a short length of 18—20 mm o.d. aluminium tubing
between the exhaust adaptor (supplied with the engine) and the
tuned silencer. The length of the intermediate tube should be
determined initially in accordance with the instructions issued
with the tuned silencer and then adjusted, as necessary, in accordance with the prop and fuel used, after test flights.
Generally speaking, this intermediate tube length will require to
be between 6 cm (2.4") and 10 cm (4"). Alternatively, a special
O.S. exhaust header pipe is available as an optional extra part.
Code No.
27101000
27101602
27102008
27103005
26704007
26705004
27106007
27107004
27108001
29008219
28009002
45010002
Optional parts
Description
Crankcase
Front Housing
Crankshaft
Cylinder & Piston Assy. (ABC)
Cylinder Head
Connecting Rod
Piston Pin
Cover Plate
Drive Washer
Woodruff Key
Propeller Washer
Propeller Nut
The specification is subject to alteration for improvement without notice.
CARBURETTOR
The special O.S. automatic carburettor described in the attached
instruction sheet is fitted, as standard, to this engine. An exhaust
pressurised fuel system should be used with this carburettor for
best results.
PARTS LIST
Code No.
27113004
26714006
26617004
9R731002
27130000
29081004
29081719
27126109
*27126202
*72101300
*72101103
Description
Screw Set
Gasket Set
Piston Pin Retainer
Ball Bearing (Front)
Ball Bearing (Rear)
Carburettor Complete (7D)
Carburettor Retainer
Exhaust Adaptor Complete
Exhaust Header-Pipe Complete
Silicone Tubing Set
Tuned Silencer
Exhaust Header-Pipe
Silicone Tubing
Tuned Silencer
O.S.
6-15 3-chome Imagawa Higashisumiyoshi-ku
Osaka 546, Japan. TEL. Osaka (06) 702-0225
ENGINES
MFG
CO
LTD
57912
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