OPERATOR’S MANUAL Snow Thrower Models 643 & 663 IMPORTANT: READ SAFETY RULES AND INSTRUCTIONS CAREFULLY Warning: This unit is equipped with an internal combustion engine and should not be used on or near any unimproved forestcovered, brush-covered or grass-covered land unless the engine’s exhaust system is equipped with a spark arrester meeting applicable local or state laws (if any). If a spark arrester is used, it should be maintained in effective working order by the operator.
TABLE OF CONTENTS Content Page Important Safe Operation Practices................................................................... 3 Assembling Your Snow Thrower ....................................................................... 5 Know Your Snow Thrower ................................................................................. 6 Operating Your Snow Thrower .......................................................................... 7 Making Adjustments .........................................
SECTION 1: IMPORTANT SAFE OPERATION PRACTICES This symbol points out important safety instructions, which if not followed, could endanger the personal safety and/or property of yourself and others. Read and follow all instructions in this manual before attempting to operate this machine. Failure to comply with these instructions may result in personal injury. When you see this symbol—heed its warning.
. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. telephone 1-800-800-7310 for assistance and the name of your nearest servicing dealer. Never operate with a missing or damaged discharge chute. Keep all safety devices in place and working. Never run an engine indoors or in a poorly ventilated area. Engine exhaust contains carbon monoxide, an odorless and deadly gas. Do not operate machine while under the influence of alcohol or drugs. Muffler and engine become hot and can cause a burn.
SECTION 2: ASSEMBLING YOUR SNOW THROWER NOTE: References to right or left side of the snow thrower are determined from behind the unit in the operating position. The “operator’s position” is defined as standing directly behind the snow thrower, facing the handle panel. • • • Unpacking • • • • • Remove screws from the top sides and ends of the shipping crate. Set panel aside to avoid tire punctures or personal injury. Remove and discard plastic bag that covers unit.
SECTION 3: KNOW YOUR SNOW THROWER Shift Lever Traction Control / Auger Control Lock Headlight Clean-out Tool Auger Drive Control Chute Directional Control Discharge Chute Electric Starter Button Primer Switch Box Choke Safety Ignition Key Auger Skid Shoe Throttle Control Recoil Starter Handle Figure 5 Shift Lever WARNING: Read, understand, and follow all instructions and warnings on the machine and in this manual before operating.
Headlight designed to clear a clogged discharged chute. Refer to Operating Your Snow Thrower section for more detailed information regarding the chute clean-out tool. See Figure 5. The headlight is on whenever the engine is running. Throttle Control WARNING: Never use your hand to clear a clogged discharged chute. Shut off engine and remain behind handles until all moving parts have stopped before unclogging. The throttle control is located on the engine.
Recoil Starter • • Rotate choke knob to FULL choke position (cold engine start). If engine is warm, place choke in OFF position instead of FULL. Push primer button two or three times. If engine is warm, push primer button once only. • • appropriate for the snow conditions that exist. Use the slower speeds until you are familiar with the operation of the snow thrower. Squeeze the auger control grip and the augers will turn. Release it and the augers will stop.
Auger Control Snow Thrower Model Drift Cutter Kit All models OEM-390-679 Z-End Jam Nut Auger Control Cable Drift Cutter Carriage Screws / Hex Nuts Figure 6 Chute Clean-Out Tool Figure 7 The chute clean-out tool is conveniently fastened to the rear of the auger housing with a mounting clip.
SECTION 5: MAKING ADJUSTMENTS WARNING: NEVER attempt to make any adjustments while the engine is running, except where specified in the operator’s manual. Frame Cover Tire Pressure (Pneumatic Tires) • The tires are overinflated for shipping purposes. Before operating check tire pressure and reduce pressure to between 15psi and 20 psi. NOTE: If the tire pressure is not equal in both tires, the unit may pull to one side or the other.
Shift Rod Adjustment Skid Shoes To adjust the shift rod, proceed as follows: The space between the shave plate and the ground can be adjusted. See Figure 11. • Remove the hairpin clip and slide the shift rod connector up, to separate the upper shift rod from the lower shift rod. See Figure 10. • • Shift Lever For close snow removal on a smooth surface, raise skid shoes higher on the auger housing. Use a middle or lower position when the area to be cleared is uneven.
wheel hub.This position gives power drive to the left wheel only, making the unit easier to maneuver. Inside Hole In Axle Both Wheels Driving • Rotate wheel assembly to align hole in the hub with the inner hole on the axle shaft. Insert klick pin in the hole. Outer axle shaft hole should be visible. IMPORTANT: NEVER operate the snow thrower with the click pin inserted through both the RIM and the OUTSIDE HOLE in the axle. Doing so can result in serious damage to the drive system.
Traction Control / Auger Control Lock chains, sprockets, gears, bearings, shafts, and shifting mechanism at least once a season. Use engine oil or a spray lubricant. Avoid getting oil on the friction wheel rubber and aluminum drive plate. Refer to Figure 9. The cams on the ends of the control rods which interlock the traction drive and auger drive controls must be lubricated at least once a season or every 25 hours of operation. The cams can be accessed beneath the handle panel.
• • • • • • NOTE: If you placed plastic film under the gas cap, be certain to remove it before operating the snow thrower Drain the gasoline from the snow thrower, or place a piece of plastic film under the gas cap. Tip the snow thrower up and forward so that it rests on its auger housing. Remove the six self-tapping screws from the frame cover underneath the snow thrower. Roll the front and rear auger belts off the auger drive pulley. See Figure 17.
WARNING: Drain fuel into an approved container outdoors, away from an open flame. Allow engine to cool. Extinguish cigarettes, cigars, pipes, and other sources of ignition prior to draining fuel. Fuel left in engine for extended periods deteriorates and will cause starting problems.
SECTION 8: TROUBLE SHOOTING Trouble Possible Cause(s) Corrective Action Engine fails to start Fuel tank empty, or stale fuel. Fill tank with clean, fresh gasoline. Fuel will not last over thirty days unless a fuel stabilizer is used. Clean fuel line. Move switch to ON position Clean, adjust gap or replace. Insert key. Connect spark plug wire. Refer to the engine manual. Open fuel shut-off valve. Engine runs erratic Loss of power Engine overheats Excessive vibration Blocked fuel line.
Models 643 & 663 4 17 11 9 16 13 8 15 1 14 5 10 6 7 3 12 2 Ref. No. Part No. 3 Part Description 1. 618-0123 RH Housing 2. 618-0124 LH Housing 3. 710-0642 Self Tapping Screw, 1/4-20 x .75 4. 711-0910A Spiral Axle, 28” 5. 714-0161 Hi-Pro Key, 3/16 x 5/8 6. 715-0143 Spring Spiral Pin, .25 x 1.25 7. 717-0528 Worm Gear, 20-tooth 8. 717-0526 Worm Shaft 9. 718-0186 Thrust Collar 10. 721-0325 Grease Plug 11. 721-0327 Grease Seal 12. 736-0351 Flat Washer, .76 x 1.
Models 643 & 663 68 70 80 65 5 73 72 27 69 82 24 55 72 27 53 71 27 68 83 74 63 59 67 69 27 54 30 6 77 78 60 81 76 24 56 79 11 75 64 5 6 32 15 13 13 8 2 14 17 20 22 10 14 21 3 11 18 16 12 41 43 28 4 1 10 26 11 9 19 31 14 43 49 15 26 48 9 7 12 23 39 14 35 26 38 28 40 42 18 9
Models 643 & 663 Ref. No. Part No. Part Description Ref. No. Part No. Part Description 1. 684-0008A Shift Arm Assembly 39. 731-1300B Lower Chute 2. 710-0458 Carriage Bolt 5/16-18 x 1.75” 40. 710-3015 Hex Cap Screw 1/4-20 x .75 3. 710-0449 Carriage Bolt 5/16-18 x 2.25” 41. 731-0921 Upper Chute 4. 710-0788 TT Screw 1/4-20 x 1” 43. 736-0159 5/16 Washer 5. 712-0429 Hex Lock Nut 5/16-18 47. 746-0901 Control Cable 6. 746-0778 Z Fitting Cable 48.
Models 643 & 663 49 3 1 2 4 48 5 43 47 11 10 9 15 14 7 12 6 8 13 44 16 51 18 27 34 10 28 52 9 13 26 35 38 30 19 32 18 31 31 16 36 30 41 33 37 17 39 40 40 24 39 42 29 20 50
Models 643 & 663 Ref. No. Part No. Ref. No. Part Description Part No. Part Description 784-5038B Skid Shoe (If Equipped) 736-0242 Bell Washer 1. 712-0116 Lock Jam Nut 3/8-24 2. 756-0178 Flat Idler 31. 3. 784-5632B Auger Idler Arm 32. 712-3010 Hex Nut 5/16-18 4. 710-0459A Hex Cap Screw 3/8-24 x 1.50 33. 784-5582A Shave Plate 5. 738-0281 Shoulder Screw 34. 710-0260 Carriage Bolt 5/16-18 x .62 6. 736-0167 Wave Washer 35. 684-0065 Impeller Assembly 7.
Models 643 & 663 26 28 29 1 30 27 2 36 3 4 9 11 16 8 4 7 10 12 15 19 6 16 19 21 5 16 16 13 22 14 17 23 18 31 33 25 20 24 34 IMPORTANT: For a proper working machine, use Factory Approved Parts. V-BELTS are specially designed to engage and disengage safely.
Models 643 & 663 Ref. No. Part No. Part Description 1. 710-1652 Hex Washer Screw 1/4-20 x .625 2. 731-1324 Belt Cover 3. 732-0710 Extension Spring 4. 710-0627 Hex Screw 5/16-24 x .75 5. 710-3005 Hex Cap Screw 3/8-16 x 1.25 6. 05896A Drive Clutch Idler Bracket 7. 748-0234 Shoulder Spacer 8. 756-0987 Pulley Half 9. 754-0346 V-Belt 10. 756-0986 Pulley Half 11. 736-0270 Bell Washer 12. 710-0230 Hex Cap Screw 1/4-28 x .50 13. 756-0313 Flat Idler 14.
Models 643 & 663 20 27 39 46 Drive Clutch Cable 42 37 5 13 7 1 11 38 6 10 40 Auger Clutch Cable 4 3 4 1 2 14 15 26 5 36 16 42 16” Wheels 42 13” or 15” Wheels 7 9 10 11 12 25 31 25 28 23 43 17 18 32 24 8 4 1 22 33 8 5 29 34 41 20 21 44 19 35 45 Blower Housing 30 1 24 1 Auger Clutch Cable
Models 643 & 663 Ref. No. Part No. Part Description Ref. No. Part No. 715-0249 Part Description 1. 710-0599 Hex Screw 25. Roll Pin 2. 784-5688 Drive Cable Guide Bracket 26. 714-0143 Klik Pin 3. 784-5687A Auger Clutch Cable Bracket 27. 684-0042C Friction Wheel Assembly 4. 756-0625 Roller Cable 28. 656-0012A Friction Disc Wheel 5. 738-0924 Hex Screw 1/4-28 29. 684-0013B Wheel Shift Rod Assembly 6. 784-5630B Frame Assembly 30. 746-0897 Drive Cable 7.
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MANUFACTURER’S LIMITED WARRANTY FOR: The limited warranty set forth below is given by MTD LLC with respect to new merchandise purchased and used in the United States, its possessions and territories. d. MTD LLC warrants this product against defects for a period of two (2) years commencing on the date of original purchase and will, at its option, repair or replace, free of charge, any part found to be defective in materials or workmanship.
