O.S. Engines 21XM - Manual (Page 7)

PIPING
Connect the water inlet tube (L=170mm) and oil transfer pipe
(L=65mm) securely as shown on page 5. In the event of either
tube becoming damaged, it should be replaced with best
quality 5.5mm OD
✕ 2.5mm ID silicone tubing.
INSTALLATION
The face of the mounting plate is precision machined flat.
Make sure that the hull's transom is also flat. The adjacent
hull structures should be as rigid as possible so that the
engine will be able to develop its full performance. Use 4mm
steel screws, such as Allen type socket head cap screws, with
locknuts or lockwashers for bolting the engine to the hull. For
extra security, apply LOCTITE to the screw threads to prevent
nuts vibrating loose.
LINKAGES
Steering Linkage
Use a high-torque servo, preferably with dual pushrods as
shown below.(A single pushrod will bend easily which results
in poor steering accuracy.)
Throttle Linkage
Use flexible 'Bowden' type cable having a 3mm OD outer
sleeve. Secure one end of the sleeve to the engine, by means
of the throttle linkage bracket supplied, and the other end to
any appropriate part of the hull structure immediately sur-
rounding the throttle servo.(See sketch) If the two ends are
not secured in this way, steering the boat will upset throttle
control. Make sure that no strain is imposed on the throttle
cable when steering fully left or right. Adjust the throttle link-
age so that the throttle can be fully closed to stop the engine
prior to lifting the boat from the water.(If necessary, consult
your R/C system handbook for setting up linkage in relation to
transmitter stick movement.)
Note : When cutting silicone tubing.....
If you should need to clean out silicone tubes, use methanol or glow-fuel, not gasoline.
Silicone tubing
Use knife or razor blade. Do not use wire cutters or pliers
Steering Arm
Steering Servo
6