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Engine Mount:
Any type of mount is fine. The Saito-180 seems to have significantly more vibration than the 120 and 150 and a soft mount for the Saito-180 might be a good idea depending on your particular airframe and tolerance for vibration. If you choose a soft mount the “Soft n Safe” mount sold by Gator RC Products is a good one as it is not too soft but provides some reduction in vibration.
Upright, Inverted, or Side Mount ?? Any engine orientation is OK. A frequent question is -- can I run the engine inverted ? A scale or pattern type model looks better with the engine
inverted. Inverted engines run fine but can be a real inconvenience when starting. Attaching a glow-plug ingniter, and keeping it on, can be a real pain. Also fuel may accumulate inside the piston when inverted,
causing hard starting, or possibly engine damage when forced over with an electric starter. This latter problem with inverted engines is minimized if you turn the engine over by hand 5 or 6 rotations before
attaching the glow plug battery; any excess fuel inside the piston will run out the exhaust (if the exhaust points downward). If you are new to 4-stroke engines it is preferable to mount the engine vertical or
sideways. It is important to note that the centerline of the fuel tank should be level with the carb or a little lower; if you invert the engine the tank may be a long way above the carb and you may have
fuel running down into the carb making it difficult to get the fuel mixtures correct. Therefore, before deciding on an engine mounting orientation remember to consider the tank location. If the idle mixture is
set correctly there should normally be no need for an on board glow system. The dreaded “hydro-locking”. Often mention is the term “hydro-locking” with inverted
engines. It is easy with an inverted engine to get the piston full of fuel and it will be difficult (or maybe impossible) to turn over the engine by hand and application of a strong electric starter may damage
the engine. The instructions with engines purchased from the Horizon Hobbies (distributor in North America) suggest that in such a situation you should remove the glow-plug and drain the excess fuel. While
this will work, I suggest that procedure is inconvenient, unnecessary, and undesirable. It does nothing except wear out the glow-plug thread, maybe strip the thread in moments of frustration, and certainly waste
a lot of time. There is a simple fix; (with glow-plug igniter removed) just pick up the model and tilt it sideways so that the exhaust port points down, turn over the prop by hand and you will see the excess
fuel that was in the cylinder run out the exhaust. For an inverted engine you should first make sure you can easily turn over the engine by hand before applying an electric starter.
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The rear-mounted throttle arm on most 4-stroke engines can make the servo linkage quite difficult. The DuBro “4-Stroke Throttle Linkage” can make the servo connection more convenient. A typical setup is shown to the left.
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Compatible Engine Mount Sizes Saito-30 Saito-40a Saito-45S,50,56,56F,62,72,82a (all these have same mounting dimensions) Saito-65,80,91S,115 Saito-100,125a Saito-120S,150,180 Saito-220,
FG-36
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The Saito Metal Mounts If you are not concerned about the extra weight of a metal mount compared to a plastic mount you should consider the Saito metal mounts. For the larger engines
like the Saito-150,180,220 the plastic mounts are probably not advisable. The part numbers for the Saito metal mounts are as follows. Saito-220 and FG-36:
SAI220A95 Saito-120,150,180 SAI120S95 Saito-100 and 125a SAI10095 Saito-65,80,91,115
SAI6595 Saito-45,50,56,72,82 SAI5095 Saito-40a
SAI40A95 Saito-30 SAI30S95
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The dimensions of the Saito metal engine mounts are shown below
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