It is of vital importance, before attempting to operate your engine, to read the general 'SAFETY INSTRUCTIONS AND WARNINGS' section on pages 2-5 of this booklet and to strictly adhere to the advice contained therein. Also, please study the entire contents of this instruction manual, so as to familiarize yourself with the controls and other features of the engine. Keep these instructions in a safe place so that you may readily refer to them whenever necessary.
SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE Remember that your engine is not a "toy", but a highly efficient internalcombustion machine whose power is capable of harming you, or others, if it is misused. As owner, you, alone, are responsible for the safe operation of your engine, so act with discretion and care at all times. If at some future date, your O.S. engine is acquired by another person, we would respectfully request that these instructions are also passed on to its new owner.
! NOTES Take care that the glowplug clip or battery leads do not come into contact with the propeller or any other rotating parts. Also check that the linkage to the throttle arm is secure. This engine was designed for model boats. Do not attempt to use it for any other purpose. Mount the engine in your model securely, following the manufacturers' recommendations, using appropriate screws and locknuts. If your engine does not have a built-in recoil starter, use an electric starter.
Near TDC ENGINE CONSTRUCTION With this engine, the piston will feel tight at the top of its stroke Piston (TDC) when the engine is cold. Cylinder Liner This is normal. The cylinder bore has a slight taper. The piston and cylinder are designed to achieve clearance a perfect when Crankshaft running they Slight taper reach operating temperature. When the engine is cold. 6 NOTES WHEN APPLYING AN ELECTRIC STARTER Do not over-prime.
NOTES ON OPERATION NOTE GUARANTEE This engine is constructed from the very best materials available and to the very highest engineering standards, using the most advanced precision machinery. However, the extremely high stresses imposed by car racing operation under very severe conditions, as well as stresses which are exacerbated by the use of powerful fuels containing very high concentrations of nitromethane, constitute hazards which are beyond a manufacturer's control.
TOOLS, ACCESSORIES, etc. The following items are necessary for operating the engine. Items necessary for starting FUEL Generally, it is suggested that the user selects a fuel that is commercially available for model two-stroke engines and contains 10-30% nitromethane. As a starting point, we recommend a fuel containing 20% nitromethane, changing to a fuel containing more nitro if necessary.
BASIC ENGINE PARTS Marine Head Glow Plug RP7 Exhaust Carburetor Type 21D Cover Plate Ball Bearing (Front) Mounting Lugs Crankshaft Crankcase 12 CARBURETOR CONTROLS (21D) shown in the sketch. (In case of 30% nitro fuel) In case of 65% nitro fuel, basic position should be approximately 45 degrees turned left from the center. Mixture gets lean when the Mixture Control Screw is turned right, while mixture gets rich when the Mixture Control Screw is turned left.
Drill a 6mm dia. hole in the required position on the model and insert the Remote Needle Valve Assembly. If necessary, install a suitable mounting plate in the model to which the Remote Needle Valve Assembly may be fitted. NOTE 90 degrees 90 degrees As the idle mixture control screw is installed with LOCTITE, it may initially feel stiff, and it is suggested to use a little larger screwdriver. The screw can be turned only 90 degrees either way.
INSTALLATION OF THE STANDARD ACCESSORIES Install the exhaust seal ring supplied. Installing the glow plug. Insert RP7 plug supplied into marine head carefully, making sure that it is not cross-threaded before tightening firmly. (All the O.S. T-Type plugs including the RP7 are not supplied with a washer.
ENGINE INSTALLATION Before installing the engine in the model, clean out the engine compartment. If any remaining sand paper and glass wool residues are not removed completely, they may be sucked into the engine and damage the engine. Touches here 1. Make sure that the engine mounting beams in the hull are parallel, with their top surfaces in the same plane.
The following procedure is suitable when a fuel containing 30% nitro-methane is used. Turn the needle-valve clockwise slowly until it stops. This is the fully closed position. Do not force to turn further. Fill the tank completely with fuel. Temporarily remove the glowplug to check that it glows bright red when energized. Open the Needle-Valve 1.5 turns from the fully closed position. Element glows when energized.
Next, disconnect the glowplug battery and try running the hull on the water. If the engine stalls, open the throttle fractionally, but try to keep the engine running as rich as possible: if it stops because of being excessively over-rich, close the NeedleValve 30˚ and try again. PRECAUTIONS When starting the engine, with the hull out off the water and no load on the engine, even below half throttle, the engine can over-rev.
FINAL ADJUSTMENT Final adjustment should be carried out only after the running-in has been completed. Having established the optimum NeedleValve setting, check the Mixture Control Valve setting as follows. Run the hull (with throttle fully open) over the longest available straight, in order to observe the model's speed. Next return the hull to the starting point, close the Needle-Valve 30˚ and repeat the run, taking note of the improvement in performance.
CARE AND MAINTENANCE 1. The minute particles of foreign matter, that are present in any fuel may, by accumulating and partially obstructing fuel flow, cause engine performance to become erratic and unreliable. O.S. 'Super-Filters' (large and small) are available, as optional extras, to deal with this problem. One of these filters installed to the pickup tube inside your refueling container, will prevent the entry of foreign material into the fuel tank.
TROUBLE SHOOTING Symptom Engine fails to fire. Corrective action Cause Fuel tank is empty. Fuel not reaching the engine. Fill the tank with fuel and repeat Priming procedure. Glowplug element is burnt out. Glowplug battery discharged Replace glowplug. Recharge or replace the battery. Clogged fuel filter Silencer inside is dirty. Clean or replace fuel filter. Clean inside silencer. Over priming Remove glowplug and pump out excess fuel. Fuel tubing is disconnected.
Symptom Unstable idle Corrective action Cause Unsuitable glowplug Use suggested glowplug in the instructions. Unsuitable fuel Do not use extremely high nitro or low oil content fuel. Extremely light flywheel Add heavier flywheel. Silencer is disconnected or has play Install silencer securely. Symptom Not reaching expected peak r.p.m. Corrective action Cause Insufficient warming up or running-in. Set the needle only after warming up. Complete running-in.
33 1 1-1 2 3 4 5 6 7 8 9 10 10-1 11 12 13 14 15 16 Description Marine Head Nipple No.18 Inner Head Head Gasket Set (0.2mm) Head Gasket Set (0.1mm) Cylinder & Piston Assembly Piston Pin Piston Pin Retainer (2pcs.) Connecting Rod Carburetor Complete (Type 21D) Carburetor Retainer Assembly "O" Ring (2pcs.) Crankshaft Ball Bearing (Front) Crankcase Crankshaft Ball Bearing (Rear) Crankshaft Cover Gasket Cover Plate Glow Plug RP7 Head Gasket Set (0.2mm) Exhaust Seal Ring (2pcs.
CARBURETOR EXPLODED VIEW C.M3X8 4 1 6 9 2 9-4 3-2 7 9-1 9-5 9-2 9-3 5 8 5-1 10 S.M3X3 3-1 3 CAP SCREW SETS (10pcs./sets) ＊Type of screw C…Cap Screw S...Set Screw Code No. Size 79871110 M3x8 Pcs. used in an engine Throttle Lever Retaining Screw (1pc.) 34 CARBURETOR PARTS LIST No. Code No.
O.S. GENUINE PARTS & ACCESSORIES SUPER JOINT TUBE 21 O.S. Glow Plug RP6 (72106300) (71642060) NON-BUBBLE WEIGHT S SUPER FILTER (L) (72403050) (71531010) RP7 (71642070) LOCK WASHER RP8 (10set) (71641800) M3 O.S. SPEED DRIVER TOOLS (55500002) O.S. SPEED PLUG WRENCH Code No. Description 71410150 71410200 71410250 71410300 71411200 71411250 71412300 71413550 71413600 71413700 O.S. SPEED HEX WRENCH DRIVER 1.5 O.S. SPEED HEX WRENCH DRIVER 2.0 O.S. SPEED HEX WRENCH DRIVER 2.5 O.S.
THREE VIEW DRAWING SPECIFICATIONS 21 3.49 cc (0.213 cu.in.) 16.27 mm (0.641 in.) 16.8 mm (0.661 in.) 4,000-45,000 r.p.m. 2.75 ps / 2.79 hp / 33,000 r.p.m. 307.5 g (10.85 oz.) 31.6 37 45 ■ Displacement ■ Bore ■ Stroke ■ Practical R.P.M. ■ Power output ■ Weight 55.6 66.15 33.5 44 31.6 45 28.5 UNF 1/4 -28 22 44 20.5 Dimensions (mm) 38 URL : http://www.os-engines.co.jp 6-15 3-Chome Imagawa Higashisumiyoshi-ku Osaka 546-0003, Japan TEL. (06) 6702-0225 FAX. (06) 6704-2722 C Copyright 2011 by O.S.
