Saito FA-120R3 User Manual

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Instructions for SAITO FA-120R3 (AAC) 4-Stroke Engine

We would like to express our sincere thanks for your purchase of the SAITO FA-120R3
engine. Please read our instructions carefully and treat your engine with care. If there’re
any manufacturing defects, SAITO Seisakusho co., ltd. will make necessary repairs free
of charge. You are requested to strictly avoid disassembling the engine since assembled
with the use of special tools and jigs to assure perfect construction.
In the case of breakage or trouble, if encountered due to crash or others, please send the
engine to our service station.
Please notice that our guarantee will not cover any breakage or trouble on the engine
caused by your disassembling or modification.

Please refer to the following data.

Principal outside dimensions

Explosion order

(1-3-2)

Prop rotational direction

1

Mechanism of 4-Stroke Engin

The 4-Stroke engine provides 4 individual piston
movements as illustrated below. The “Stroke” means the
piston movement from the Top Dead Center to the Bottom
Dead Center. In the 4-Stroke engine, one cycle of operation
in change of gas state inside the cylinder and valve
movement are completed at every 4 strokes of piston that is
every 2 revolutions of the crankshaft. Formally the engine is
called the 4-stroke one-cycle engine.

23

Cylinder numbers viewed
from the rea

Bore 22.4mm×3 Weight Approx. 890g (with mufflers) Propeller Standard APC13"×8"-14"×6"
Stroke 16.2mm×3 Practical Speed 1,800-10,000rpm max range on the ground: 8,500-9,500rpm
Stroke volume 19.18cc Static thrust Approx. 3.5kgf (by APC14"×6"prop)

Fuel flow

Unique features of SAITO F A-120R3

• Optimum for small-size scaled airplane

• Low vibration (assured by constant-interval explosion)

• Real sound of the exhaust.

• The engine is designed to equalize fuel mixture and minimize misfire due to insufficient distributing at idling by means of special port type intake manifold

originally developed by SAITO.

• Cylinder head: Improved semi-spherical combustion chamber assures better combustion efficiency and volumetric ef ficiency .

• Cylinder: The aluminum cylinder is directly hard-chrome plated on its in ner surface without installing liners to reduce weight and increase durabilit y . The monolithic

structure of cylinder head and cylinder prevents distortion and improves cooling efficiency.

• Piston: The piston is made of high silicon content aluminum and a ttached with a compression ring to heighten engine performance.･

• Crankshaft: Has a forged solid construction made of chrome molybdenum steel, and supported by two ball bearings.

• Cam: Features high cam providing longer maximum lift time.

• Carburetor: High-performance of slow throttling type.

• Propeller nut: designed to have double nuts preventing loosening and fall-off for the safety .

Standard Accessories

1. Wrench for tappet adjusting screw 1 pc. 5. Glow plug [SAI-GP01, P-SS] 3 pcs.

2. Limit gauge (0.1t) for tappet adjusting 1 pc. (Attached to the engine)

3. Hexagonal wrench (1.5mm) 1 pc. 6. Plug heating connector set 1 set

4. Muffler complete 1 set (3pcs. of red cord, 1pc. of black, 2pcs. of fixture)

24cc/min (At full throttle, Fuel of synthetic oil with 15% of nitro content,APC13"×6"prop at approx 9,400rpm)
*Fuel flow varies depends upon prop load. More fuel flow with larger load and less fuel flow with smaller load.

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