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Yamato 302 Manual

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302
M
O
D
E
L
M A N U A L
YAMATO MOTOR CO. LTD.
Ota • Japan
November 2012

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Summary of Contents for Yamato 302

  • Page 1 M A N U A L YAMATO MOTOR CO. LTD. Ota • Japan November 2012...
  • Page 2 YAMATO EUROpE www.YamatoRacing.co.uk...

  • Page 3: Table Of Contents

    VI pERFORMANCE CURVE ........26 VII SpECIFICATION FOR MODEL 302 ......27...

  • Page 4: Forward

    F O RWA R D The Yamato model 302 is a 396cc / 24. 2 cubic inch stock racing engine. Like it's predecessors - the models 80, 102 and 202 - this motor was developed specifically for use in the multi-billion Yen parimutuel boat racing industry in Japan. These motors are required to run heats, day after day with perfect reliability at racing speeds.

  • Page 5: General

    As in most form of racing, there is risk which may bodily injury. The Yamato Motor Co. suggest that extreme caution be taken whenever you operate this motor and cannot be responsible or liable for any mishaps that may occur while operating this motor.

  • Page 6: Operation Of Motor

    II OpERATION OF MOTOR II - 1 precaution prior to Starting Motor A. Check thumb screw handles to be sure it is tight. B. Check for oiI in gearcase. C. Check condition of high tension wires and spark plugs. Ensure it is firmly tightened. D.

  • Page 7: If Hull Fails To Plane

    For safety reasons, we suggest that the air idling screw be set all the way in and the throttle stop backed-off completely so that the motor will not continue to run if the driv- er is thrown out of the boat. Figure 1 Figure 2 II - 3 If Hull Fails to plane...

  • Page 8: Care Of Motor After Use

    II - 6 Care of Motor After Use A. Wipe spilled gasoline with clean rag. B. Wipe water, around powerhead. C. If motor has been used in salt water, flush motor internally as well as externally with fresh water. CAUTION: Do not tip motor upside down. Water can enter the exhaust port and can cause serious damage.
  • Page 9 m. Attach high tension wires to spark plug. GROUND spark plug. n. Pull starter pulley and check spark plug. Both plugs must be firing. o. Reassemble (except propeller), refuel and run motor, for 30 seconds at intermediate speed. p. Replace propeller. CAUTION : Remove spark plug wire when installing or removing propeller.

  • Page 10: Disassembly, Inspection And Reassembly

    III DISASSEMBLY, INSpECTION AND REASSEMBLY III - 1 pOWER UNIT A. Disassembly 1. Remove magneto assembly (see magneto section). 2. It is not necessary to remove fuel tank. However, for the beginner, it will be easier to work without it. 3.

  • Page 11: Inspection

    Inspection 1. Slight scratches on cylinder wall is permissible. Hone if necessary. 2. Replace piston rings if gap exceeds 0.812 mm (0. 032"). 3. To check crankshaft, remove all bearings. Place "V" blocks on surface plate. Support crankshaft ends on "V" blocks. Check by placing dial indicator on center bearing surface while turning crankshaft.
  • Page 12 8. Install piston rings. The side that faces cylinder head is marked with a “T”. 9. Be sure that cylinder block and crankcase is flush at bottom. Torque cylinder to crankcase nut 30 ~ 34 Nm (300 ~ 350 kg cm / 22 ~ 25 ft lbs). See figures 7 and 8.
  • Page 13 Figure 7 Figure 8 10. Be certain that exhaust pipe is flush with lower unit. See figure 9. 11. Torque cylinder head 20 ~ 24 Nm (200 ~ 250 kg cm / 14 ~ 18 ft lbs). See figure 10 for proper sequence. CAUTION: It is of utmost importance that all bolts and nuts be torqued as specified.
  • Page 14 pOWER UNIT GROUp – 11 –...
  • Page 15 pOWER UNIT GROUp – 12 –...

  • Page 16: Magneto

    III-2 MAGNETO A. Disassembly 1. Remove starter pulley bolt (P-67) and washer (P-82). 2. Remove starter pulley (P-28). 3. Remove key (P-98). 4. Remove four clamp plate nuts (M-42) washers (M-20) and clamp plates (M-41). 5. Remove coil plate assembly (M-1). Tap with soft hammer to lift up. See figure 11.

  • Page 17: Reassembly

    B. Reassemble in reverse order with following precaution. 1. Lubricate inside of coil plate assembly with grease. 2. Insure that flywheel key is seated properly. 3. Use clamp flywheel - special tool 102-809-0100 - when tightening flywheel. Tighten 54 ~ 63 Nm (550 ~ 650 Kg cm / 40 ~ 47 ft lbs). 4.
  • Page 18 MAGNETO GROUp – 15 –...
  • Page 19 CARBURETTOR GROUp – 16 –...

  • Page 20: Inspection

    5. Remove spring plate (C-17). 6. Loosen holder (C-12). 7. Remove main needle (C-16) assembly. 8. Remove plugs (C-36, 28) and pilot screw (C-38). 9. Remove jet (C-27, 30, 31). 10. Clean body and all parts in clean solvent. 11. If extremely corroded or dirty, soaking in commercial carburettor cleaner is recom- mended.

  • Page 21: Gearcase

    III-4 GEAR CASE A. Disassembly 1. Using wrench, tail cap - special tool 102-801-3030 - loosen tail cap (G-31). CAUTION: LEFT HAND THREAD. 2. Remove tail cap and propeller shaft assembly by : a. Removing O-ring (G-39) b. Removing clip (G-38) c.

  • Page 22: Inspection

    B. INSpECTION 1. When draining gear oil, check for water in gear case. If oil appears white, replace oil seals and O-ring. 2. Inspect gear for wear, pitting and full contact. If gears are not in full contact, shaft may be bent or shim adjustment is incorrect. 3.
  • Page 23 LOWER UNIT GROUp – 20 –...
  • Page 24 LOWER UNIT GROUp – 21 –...
  • Page 25 GEAR CASE GROUp – 22 –...
  • Page 26 FUEL TANK GROUp – 23 –...

  • Page 27: Troubleshooting

    IV  TROUBLESHOOTING – 24 –...

  • Page 28: Cross Section Of Motor

    V. CROSS SECTION OF MOTOR – 25 –...

  • Page 29: Performance Curve

    VI  pERFORMANCE CURVES YAMATO 302 pERFORMANCE CURVES Horsepower (HP) Torque (kg-m) Fuel Consumption (g/PSh) 3000 4000 5000 6000 7000 Engine Revolution (RPM) – 26 –...

  • Page 30: Specification For Model 302

    VII SpECIFICATION FOR MODEL 302 1. Horse Power ......24 Kw (33 h.p.) at 6,600 RPM 2. Maximum Torque......3.7 Kg cm / 26.8 ft lbs at 5,500 RPM 3. Bore x Stroke ......66 x 58 mm / 2.598 x 2.283 4.

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