User Manual

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A. Fuel
We recommend the use of synthetic oil fuel having good quality for glow engines with 5 to20% of nitro content.
Since exhaust temperature of 4-stroke engine is high, avoid using castor oil as it tends to accumulate the carbon.
Also installing a fuel filter is recommended.
B. Fuel tank
Select a suitable capacity of fuel tank for the model airplane available in the market referring to the data.
Set the tank as the liquid level to be the same height as the center of carburetor.
Also place the weight of the fuel inlet at a distance of approx. 3-5mm from the firewall.. Since SAITO engines use muffler pressure, careful attention is required for leakage.
Moreover regulate the silicon tube length of piping to the minimum necessary extent.
C. Plug
Since one explosion occurs in every two rotations in 4-stroke engines, selection of the plug is important. Use of improper plug causes engine trouble. Engine performance
varies according to the matching with the fuel or to the season. We recommend testing various types of plugs for the best performance.
(Some types of plug by other manufacturers exhibit good matching with SAITO engine. The plug deteriorates after many flight hours even if not broken. Hence frequent
replacement with new one would be necessary. Please recognize a plug as a consumable part.)
D. Propeller
Select the standard size prop ranges from APC13”x8”-14”x6” although it varies according to the body type of airplane. Select one with high reliability available in the
market.
The prop requires thorough balancing. Use a balancer to attain correct balancing. Unbalanced prop creates excessive vibration, lowers performance and invites danger. If
you find flaw or other defects, replace the prop with new one since dangerous.
For the characteristics of this engine, use a prop that matches to the airplane and turns smooth in 8,500-10,000rpm of the maximum speed range on the ground.
Prop speed varies by manufacturers and also in some instances, among props of the same size by the same manufacturer. We recommend testing various types of props.
E. Preparation for Engine starting
1. Mount the engine on the sturdy test bench with correct parallelism or on the fuselage. Fix the test bench or fuselage to prevent moving.
2. Use a fuel tank with a capacity of 300-400cc to test the engine on the bench, or use the adequate tank on the fuselage.
3. Use fuel with approx. 20% of oil and 15% of nitro content, other than low-oil fuel.
4. For test prepare APC14”x6” prop (Standard rotation at approx. 9,500rpm)
Securely tighten double nuts to fix the prop. Also attach the spinner nut for use of a starter.
5. Attach silicon tube to the breather nipple to check the exhaust from the breather.
6. Connect silicon tube from the muffler nipple to the fuel tank to use muffler pressure. (Be sure to check that there’re no leaks throughout the tube.)
7. Unlike 2-stroke engines it is difficult to judge clearly the peak condition on 4-stroke engines. Prepare a tachometer to prevent over-throttling or overheat.
8. Prepare starter, its battery, plug heat, and other necessary articles.
F. Engine starting
The following is the procedure with the engine mounted on the airplane.
(A) Starting method with a starter (Recommended)
1. After confirm that the throttle stick is located at the full-close position, turn on the transmitter switch. Then turn on the receiver switch to check throttle valve operation.
(After checking fully close the throttle valve.)
2. Open main needle by about 3turns. (It’s just for a guide. Further open the main needle if fuel mixture is lean or close if rich after starting the engine. Additionally note
that larger prop requires further opening and smaller prop closing.)
3. Open the throttle valve about 1/4 to 1/3 from the full close position by using the throttle stick. (Starting with excessively opened throttle is dangerous since the airplane
jumps forward.)
4. Turn the prop in reverse direction (CW) until it gets compression.
5. Heat the plugs. (Heat 3 pieces of plug separately if the battery has lower capacity.)
6. Apply the starter to the prop and activate for about 5 seconds to start the engine.
Fuel filter [F-1] Weight: 10g
SAITO fuel filter “F-1” exhibits the highest performance
Use of SAITO “SAIT GP01” SS Glow plug is recommended.
Note: Avoid operating the engine with a prop allowing over 10,000rpm on the ground or a large load prop lowering speed below 8,500rpm.
Crankshaft, bearings, master rod, cam or gear would be damaged otherwise.
Note: Please tighten regularly a t least once in ten flights. Especially for a wooden prop, it tends to compressed so that the nuts are rather easy to be loosen so please
confirm carefully that the nuts are tightened adequately.
If there’s anyone stands forward, be sure to have them move behind the airplane prior to start the engine. Also keep one of your arm holding the airplane away from the
prop. On starting the engine, move to the rear of the airplane. Make needle adjustment or other control from the rear. If the airplane cannot be fixed, ask your assistant
to hold the airplane for safety.
Caution: Do not activate the starter at the position which the engine is getting compression in the forward direction (CCW) since dangerous.