SERVICE BULLETIN LAWN-BOY PRODUCTS WALK MOWER #38 September 25, 2006 Dura Force Carburetor Kit PRODUCT: Walk Behind Mowers UNITS AFFECTED: Model Numbers: Serial Numbers: 10247 8900001-230999999 10247C (Int l) 210000000-230999999 10250 8900001-8999999 10252 9900001-220999999 10323 8900001-240999999 10324 8900001-240999999 10324C (Int l) 210000001-240999999 10331 8900001-8999999 10332 8900001-8999999 10424 8900001-240999999 10425 8900001-8999999 10525 8900001-200999999 10527 8900001-8999999 10547 8900001-200999999 10548 8900001-8999999 10550 210000001-240999999 10552 210000001-230999999 10928 (Int l) 200000001-210999999 11002 (Int l) 8900001-200999999 11003 (Int l) 8900001-210999999 22260 8900001-240999999 22261 8900001-240999999 SUBJECT: SITUATION: Carburetor assemblies have been replaced by a carburetor kit. Complete carburetor assemblies for the Dura Force engine are no longer available. If you order the complete carburetor you will receive a kit containing all of the individual components. Detailed repair instructions for carburetor assembly can be found in the E Engine Service Manual, form # 492-0647. A copy of the manual instructions are attached. Note: Exceeding specified torque value on the jets or screws can damage the carburetor body. Svc Mgr Tech 1 Tech 2 Tech 3 Tech 4 Tech 5 Parts Mgr Sales Mgr Warranty Mgr Initials
LAWN-BOY PRODUCTS WALK MOWER #38 (9-25-06) Page 2 WARRANTY: PARTS: Does not apply; information only. 107-4607 Carburetor Kit
ASSEMBLY Important: Over-tightening the jets or main nozzle can damage the carburetor body. 3. Apply one drop of Loctite 242 blue to the threads, and install the pilot jet (Fig 02). Torque to 10-12 in-lbs. (1.1-1.3 Nm). 1. Install the high speed jet into the fuel nozzle. Torque to 4-6 in-lbs. (.44 -.66 Nm). 2. If the nozzle has been removed, turn the carburetor over. Apply one drop of Loctite 242 blue or equivalent to the nozzle threads, and install the nozzle assembly into the carburetor body (Fig. 01). Torque to 16-28 in-lbs. (1.7-4.0 Nm). Fig 02 0893-030 4. Apply one drop of Loctite 242 or equivalent to the seat threads, and install a new brass inlet fuel valve seat (Fig. 03). Torque to 16-28 in-lbs. (1.7-4.0 Nm). Fig 01 0893-038 Fig 03 0893-041 1
5. Install a new inlet valve needle and clip on the fl oat. 6. Install the fl oat assembly with a new fl oat hinge pin in the bottom of the carburetor. Ensure that the hinge pin is positioned properly to keep the fl oat level. The fl oat should be free to move up and down easily in the carburetor body. 7. Adjust fl oat so height is 1/2 ±.03 (.76 mm) from bowl fl ange (gasket not in place) to top of fl oat (Fig. 04). 8. Pressure check carburetor. Attach pump with pressure gauge to fuel inlet fi tting on carburetor (Fig. 05). With carburetor upside down (fl oat up), raise fl oat and lower to its normal position. Pump pressure to 5 psi (.35kg/cm). It should hold this pressure indefi nitely. For practical purposes, test for 10 or 15 seconds. If it does not hold, wet the needle and seat, and repeat the test. Fig 05 0893-026 Fig 04 0893-054 9. Install the fuel fi lter over the fuel nozzle (Fig. 06). Fig 06 0893-022 2
10. Install a new fuel bowl gasket and the fuel bowl with the four bowl retaining screws (Fig. 07). Torque to 10-13 in-lbs. 12. Place the collar and spring over the carburetor fi tting (DuraForce engines) (Fig. 09). Fig 07 0893-002 Fig 09 0893-005 11. Hook the governor spring into the bottom of the governor collar (DuraForce engines) (Fig. 08). 13. Install the air vane and throttle shaft into the carburetor body by very carefully pushing the shaft through the collar into the carburetor body. (Fig. 09). 14. Push the throttle plate into the throttle shaft. (The plate only inserts one way.) If the throttle plate does not fi t snugly, replace the throttle shaft. The governor spring can now be attached to the throttle shaft. Note: Be sure air vane operates smoothly and does not stick or bind. Fig 08 0893-050 3
INSTALLATION 1. DuraForce - Assemble the carburetor, gaskets, heat shield, and air fi lter box. Use the two mounting screws to hold the parts together during assembly. 2. DuraForce engines - Guide the air vane through the opening in the shroud base from the bottom of the base, and attach the carburetor to the engine with two mounting screws. Tighten them to specifi cations. 3. DuraForce engines - Insert the bent wire of the throttle cable into the vertical tab of the speed control lever. Set the throttle to fast and the speed control lever so that the throttle plate is in the full open position. The cable is adjusted at the cable clamp on top of the air fi lter box. 4. Install the fuel line and primer tube on the appropriate carburetor fi ttings. 5. Check that the choke and air vane assembly move freely and is properly adjusted. If the air vane requires adjusting, see Presetting the Governor on page 26. 6. Install the air fi lter element and cover. 4