MASSEY FERGUSON MF 370A (01) PDF MANUAL

1. Remove nuts securing cover and guide bar and remove bar and chain.

2. Remove handle cover, disconnect wire terminals and remove switch and controls.

3. Remove plugs and brushes.

4. Remove screws on motor side securing gear case and remove case.

5. Pry lightly against armature and lift armature out.

6. Back out screws and remove air baffle.

7. Use a screwdriver and unhook wire spade from brush holder.

8. Remove field coils.

1. Install field coils and connect wires to brush holder.

2. Place gasket over coil assembly and secure assembly in place with air baffle and screws.

3. Install armature.

4. Install gear case over splined end of armature shaft and secure with retaining bolts.

5. Install brushes and secure with plugs.

6. Connect wire connectors to switch, position switches in handle, hold in place with one hand and install handle cover.

7. Install guide bar, chain and cover.

8. Adjust chain as follows:

a. Loosen bar retaining nuts, hold nose of bar up and turn adjusting screw until chain side links just contact bottom of guide bar.

b. While holding bar up, tighten guide bar nuts.

c. Pull forward on upper side of chain. Chain should rotate around bar freely. If not chain is too tight.

1. Remove chain shield, guide bar and chain.

2. With an impact wrench, rotate clutch assembly clockwise on crankshaft and remove clutch. NOTE: A screwdriver can be inserted through recoil start housing and into reinforced area of flywheel to hold crankshaft from turning. Then rotate clutch clockwise and remove.

3. Remove screws in front handle and remove handle.

4. Remove four screws and remove cylinder frame and handle.

5. Remove air filters, carburetor, reed plate, throttle lever and linkage.

6. Use a screwdriver and pry crankshaft seal cap off case and remove seal.

7. Remove recoil starter and nut securing flywheel to crankshaft. NOTE: An impact wrench is helpful in removing flywheel nut (right-hand threads).

8. Screw a 5/16-24 UNF bolt and nut on crankshaft and remove flywheel.

9. Remove cover over points and disconnect wire from points. Points and condenser can be removed if desired.

10. Push down on manual oiler button (if equipped) and remove retaining ring. Pull button off plunger rod.

11. Remove screws securing fuel tank and cover to crankcase and lift off.

12. Rotate crankshaft until keyway on shaft is toward top of cylinder. NOTE: This is a two piece crankshaft and piston must be positioned up to clear crankshaft during disassembly or reassembly.

13. Remove four screws and remove bearing carrier and flywheel half of crankshaft.

14. Remove nuts securing cylinder to crankcase and move cylinder off studs. Carefully lift rod off crankshaft and remove rod, piston and cylinder as an assembly. NOTE: Rod bearing is caged loose needles and may fall out. If so they can be retained in cage with grease for reassembly.

15. Remove piston from cylinder.

Inspect all parts for wear or damage and replace all seals and gaskets. Most of the needle bearings are loose caged needles (drawn cap needle bearing grease retained rollers) and may fall out during disassembly. A small amount of grease will hold roller in place during reassembly. Inspect, if cylinder is badly scored replace with new cylinder. Do not attempt to rebore, it is chrome plated approximately .002″ thick. If piston is removed from rod, reinstall piston pin with closed end of pin toward exhaust side. Use CV Locktite Catalog #242 on screws to hold securely.

1. Inspect bearings, if replacement is necessary press against lettered side of bearing. Install all bearings flush with edge of casting.

2. Install rings on piston and align pin in ring groove with end of piston rings.

3. Position piston so EXH marking on top of piston is toward exhaust side of cylinder.

4. Compress rings and insert piston into cylinder.

5. If removed install drive half of crankshaft into crankcase.

6. Position crankshaft at T.D.C. then pivot connecting rod into recess area and install onto crankshaft.

7. Slide cylinder over studs in crankcase and secure with retaining nuts.

8. With cylinder at T.D.C. install bearing carrier and flywheel half of crankshaft. Secure with retaining nuts.

9. Reinstall fuel tank and cover to crankcase and secure with retaining screws.

10. Install manual oil control plunger and button (if equipped).

11. Install crankshaft oil seal and retainer on flywheel side.

12. Install points and adjust to .015″ gap. NOTE: Point gap setting will change due to two piece crankshaft. When checking gap hold crankshaft against point cam block.

13. Install coil if removed and connect coil and condenser wires to points.

14. Install flywheel and adjust air gap between coil and flywheel to .008″. NOTE: Hold flywheel against coil to set air gap.

15. Install crankshaft seal and retainer on clutch side.

16. Install reed plate, carburetor and throttle linkage.

17. Position switch and throttle lever and install frame and handle.

18. Install front handle.

19. Install clutch assembly.

20. Install chain, guide bar and shield and adjust chain tension as outlined in Operator’s Manual.

21. Adjust chain as follows:

a. Loosen bar retaining nut, hold nose of bar up and turn adjusting screw until chain side links just contact bottom of guide bar.

b. While holding bar up tighten guide bar nut.

c. Pull forward on upper side of chain. Chain should rotate freely around bar. If not chain is too tight.

1. Remove chain shield, guide bar and chain.

2. Remove recoil starter assembly.

3. Place screwdriver in reinforced area of flywheel and turn clutch assembly clockwise (left-hand threads) with special tool. Be sure screwdriver is next to heavy portion of flywheel. NOTE: A tool can be fabricated so clutch assembly can be removed with an impact wrench.

4. Remove flywheel as follows:

a. Remove retaining nut.

b. Screw a 5/16″ 24 UNF bolt and nut on crankshaft.

c. Hold flywheel with one hand and strike bolt.

5. Remove cover and air filter over carburetor and disconnect and remove choke control.

6. Remove handle cover and air filter bracket.

7. Notice that throttle control wire is located in third hole from top in counterclockwise direction on throttle shaft. Then remove wire, throttle lever, detent lever and switch. When releasing detent lever from handle, be careful spring will come out and be lost. NOTE: Units with automatic oiler system the throttle wire is located under metering pump link.

8. Disconnect fuel line and remove carburetor observing order and positioning of gaskets.

9. Remove four screws in carburetor chamber. One screw on right bottom side of saw, two lines (automatic oiler) on left side of saw, and remove oil tank assembly.

10. Remove four screws on clutch side of saw and separate engine from fuel tank.

11. Unhook coil wire and remove coil assembly.

12. Remove four retaining nuts and remove cylinder from piston.

13. Remove bearing retainer from side of engine crankcase.

14. Work through side and top openings and remove piston and rod from crankshaft. NOTE: Crank end of connecting rod has 31 loose needle bearings. Piston end has a caged bearing.

15. Remove screws and retainers from groove in crankshaft bearing.

16. Bump end of crankshaft and remove shaft and bearing from crankcase. NOTE: A board with 1″ hole on open jaws of a vise makes a convenient holder.

Inspect all parts for wear or damage and replace all seals and gaskets. Most of the needle bearings are loose caged needles (drawn cup needle bearing grease retained rollers) and may fall out during disassembly. A small amount of grease will hold rollers during reassembly. The crankshaft end of connecting rod has 31 loose needle bearings. If piston is removed from rod, reinstall piston pin with closed end of pin toward exhaust side and connecting rod with match marks opposite exhaust side. Use Locktite CV (Catalog Number 83) or a suitable substitute medium strength product for use on coarse threads and fittings such as nut lock, hydraulic sealant, etc.

1. If removed, install bearing on clutch end of crankshaft with groove in bearing race toward center of crankshaft.

2. If necessary to replace needle bearings, press against lettered side of bearing and position flush with housing.

3. Install seal in crankcase with lip inward and flush with housing.

4. Insert crankshaft and bearing into crankcase and secure with retainer clips and screws. Use CV Locktite on screws. Be sure crankshaft does not contact screws when rotated.

5. Count needle bearings and locate mating marks on connecting rod.

6. Position needles in rod with grease.

7. Set rod and piston aside and position needles in rod cap. Work through side and position rod cap on crankshaft with mating mark out.

8. Hold rod cap with one hand and set rod and piston onto crankshaft with mating mark out. Secure rod and cap together with retaining screws.

9. Install rings on piston and align pin in ring groove with end of piston rings.

10. Install seal in bearing retainer and install bearing retainer.

11. Position cylinder over piston so EXH marking on top of piston is toward exhaust side of cylinder.

12. Compress rings and slide cylinder over piston and studs in crankcase. Secure cylinder to crankcase with retaining nuts.

13. Position coil on cylinder, hold up, away from crankshaft, and lightly tighten screws. Position wire in groove. Mounting screws on coil will be tightened later when flywheel is installed.

14. Position engine into fuel tank assembly and secure with retaining screws.

15. Insert reed valve assembly and thick cork gasket into carburetor opening in crankcase.

16. Position oil tank assembly with wires and lines routed as shown. Secure with retaining screw – four screws in carburetor chamber and one screw on right lower side of saw. Reconnect oil lines.

17. Install carburetor making sure all gasket holes are aligned.

18. Install switch with detent spring.

19. Install throttle control wire, throttle lever and handle cover. Throttle control wire is connected to 3rd hole from top, in counterclockwise direction on throttle shaft. NOTE: On models with automatic oiler, throttle shaft is placed under metering pump link.

20. Install choke control, air filter bracket, air filter and cover.

21. Reinstall points (if removed), adjust gap to .015″ and install flywheel. Adjust air gap between coil and flywheel to .008″. NOTE: A shipping tag serves as a convenient gauge to set air gap.

22. Install clutch, chain and guide bar. Adjust chain as outlined in Operator’s Manual.

23. Install recoil starter.

24. Adjust chain as follows:

a. Loosen bar retaining nuts, hold nose of bar up and turn adjusting screw until chain side links just contact bottom of guide bar.

b. While holding bar up tighten guide bar nuts.

c. Pull forward on upper side of chain. Chain should rotate freely around bar. If not chain is too tight.

Maximum power and efficiency are possible only with proper carburetion. Improper carburetor adjustments can cause overheating, spark plug fouling, poor lubrication and lack of power.

Use a good quality of SAE 30 engine oil mixed with regular gasoline 16:1 ratio. Fuel/oil ratio should be increased during break-in period to 3/4 pint oil to 1 gallon gasoline. This mixture should be used for first gallon of gasoline.

High speed mixture screw is identified by letter “H” and low speed by letter “L”.

1. Stop engine and turn both fuel mixture screws in until they bottom (do not force).

2. Back out both fuel mixture screws 3/4 turn. This is an initial setting.

3. Start engine and warm up, return to idle and if necessary adjust low speed mixture screw until engine runs smooth.

4. Speed engine quickly, if engine doesn’t accelerate or hesitates, open high speed mixture screw 1/16 turn at a time and check again. It may be necessary to open low speed mixture screw slightly.

NOTE: Never operate engine on a lean mixture or damage could occur due to lack of lubrication and overheating.

High speed mixture screw is identified by letter “H” and low speed by letter “L”.

1. Stop engine and turn both fuel mixture screws in until they bottom (do not force).

2. Back out low speed mixture screw 1-1/8 turns and high speed mixture screw 1 turn. This is an initial setting.

3. Start engine and warm up, return to idle and if necessary adjust low speed mixture screw until engine runs smooth.

4. Speed engine quickly, if engine does not accelerate or hesitates, open high speed mixture screw 1/16 turn at a time and check again. It may be necessary to open low speed mixture screw slightly.

1. Remove fuel pump cover, gasket and diaphragm.

2. Remove screens.

3. Remove four screws and lift off metering diaphragm cover.

4. Remove metering diaphragm and gasket.

5. Remove two flat head screws and lift off plate, lever and inlet needle.

6. Remove spring, black circuit gasket and metering rod.

7. Remove retaining ring and screen.

1. Install metering rod, screen and retaining ring.

2. Position black circuit gasket and lever spring into place.

3. Hook inlet needle in lever and install over spring.

4. Secure plate and lever assembly with flat head screws and check height of lever. If lever is not level with gasket surface of carburetor housing, carefully bend to correct.

5. Position metering diaphragm and gasket over lever, and install cover.

6. Reinstall screens.

7. Install fuel pump diaphragm, gasket and cover.

1. Remove low speed mixture and high speed mixture screws.

2. Remove fuel pump cover, gasket and diaphragm.

3. Remove main diaphragm cover.

4. Unhook main diaphragm from control lever and remove.

5. Remove screw and lift out lever, pin, spring and inlet needle.

6. Carefully drill a small hole in each welch plug. This hole should just break through plug. Deeper drilling will damage body casting beyond repair. A plastic insert is under large welch plug to help prevent damage. This plug is included in carburetor repair kit.

7. Use a small punch and pry welch plug from openings.

8. Remove retaining ring, screen and plastic insert.

9. Remove governor valve assembly.

10. If choke shaft requires removal, hold hand over hole at end of shaft to prevent detent ball and spring from being lost.

1. If removed, reinstall throttle shaft and spring.

2. Install choke shaft, detent spring and ball.

3. Install governor valve assembly and gasket.

4. Install screen, retaining ring and plastic insert.

5. Install welch plugs with convex side up, and flatten with a flat tool slightly larger than the welsh plug.

6. Install inlet needle, spring and lever and secure with retaining screw.

7. Check diaphragm end of lever. Control lever is properly set when flush with housing as shown. If lever is not correct bend lever.

8. Hook main diaphragm to control lever, and secure in place with cover and screws.

9. Install fuel pump diaphragm, gasket and cover.

Improper filing can ruin chain faster than anything else. Use a chain filing vise if one is available. If not file chain while it is on guide bar, but be sure chain tension is properly adjusted.

1. File all cutters on one side, then opposite side and file from inside to outside of cutter.

2. Line up filing angle mark on file holder so it is parallel with chain. Keeping guide line in this position will file chain at recommended 35° angle.

3. Hold file level, use a few firm, long, even strokes.

4. After one side has been filed, move to other side and file in same manner.

5. Use tool and check depth gauge on chain.

6. If depth gauge on chain projects above tool file down.

7. Round off front corner to maintain original shape.

1. Remove recoil starter assembly.

2. Untie knot at starter pulley and pull rope out.

3. Remove “E” ring and washer from center post and lift pulley out.

4. Tie knot in one end of rope and thread other end into hole in pulley.

5. Thread rope through hole in starter housing and attach handle to rope.

6. Reinstall pulley into housing and secure with retaining washer and “E” ring.

7. Position rope in notch in pulley and turn pulley clockwise seven turns. Hold pulley and pull rope to take up all slack. Release pulley and allow rope to recoil into housing.

1. Untie knot at end of rope and release spring tension.

2. Remove “E” ring and washer and lift pulley out.

3. Remove screw and washer holding spring in place, and remove old spring.

4. Install new spring and secure in place with screw and washer.

5. Install spacer plate, pulley and rope and secure with washer and “E”-ring. Rotate pulley seven turns clockwise to wind spring.

1. Remove recoil starter assembly.

2. Untie knot in rope at pulley and pull rope out.

3. Rotate pulley in a clockwise direction eight turns. Align hole in pulley with hole in starter housing and hold in place with a screwdriver.

4. Insert rope through housing into pulley and tie a knot. Release pulley and allow rope to recoil on pulley.

1. Untie knot at end of rope and release spring tension.

2. Remove “E” ring and washer, and carefully lift pulley out. Remove plastic spacer and spring.

3. Insert new spring, plastic spacer and pulley into housing and secure with “E” ring and washer.

4. Rotate pulley eight turns clockwise, insert rope, tie knot and release pulley.

1. Ignition switch – Be sure switch is in on position.

2. No fuel – Fill tank with clean, properly mixed fuel.

3. No spark – Remove spark plug, lay on engine with wire attached. Crank engine, spark should jump across plug points. If not try a new plug. If spark doesn’t jump with new plug, check points, coil and condenser.

4. Check ground wire from magneto to ignition switch – Replace as necessary.

5. Carburetor out of adjustment – Adjust as required.

1. Air filter plugged – Clean or replace filter.

2. Port holes plugged – Remove muffler and clean.

3. Dull chain – Sharpen or replace.

4. Carburetor out of adjustment – Adjust as required.

1. Air filter plugged – Clean or replace filter.

2. Carburetor out of adjustment – Adjust as required.

3. Port holes plugged – Remove muffler and clean.

4. Weak spark – Check magneto, points and condenser.

1. Carburetor out of adjustment – Check idle mixture adjusting screw and idle speed screw.

2. Carburetor diaphragm damaged – Replace as required.

3. Crankshaft seal leaking – Replace as required.

1. Intermittent short in electrical system – Check ignition switch, electrical wiring and magneto.

2. Weak condenser – Replace condenser.

NOTE: Two cycle engines when idling may appear to be misfiring. This will not affect operation under load.

1. Connecting rod bearing worn – Move flywheel back and forth quickly. If rod is worn a loud click can be heard. Replace necessary parts.

1. Cooling fins restricted – Clean fins.

2. Incorrect fuel mixture – Too lean fuel mixture or insufficient oil in mixture. Adjust carburetor and check fuel oil mixture.

1. Carburetor inlet needle not seating – Repair or replace.

2. Hole in diaphragm – Replace diaphragm.

3. Carburetor out of adjustment – Adjust carburetor.

1. Engine is idling too fast – Check carburetor adjustments.

2. Clutch springs weak or broken – Replace as required.

1. Saw not held properly by operator – See Operator’s Manual.

2. Bent guide bar – Replace guide bar.

3. Cutting angles not uniform usually long on one side – Sharpen saw and cut angles to uniform length.

4. Depth gauges not uniform height – File saw and depth gauges.

5. Bar rails worn and spread – Turn bar over or replace and use more oil.

1. Cutters dull – Sharpen saw.

2. Cutters not same length – Sharpen saw.

3. Chain tension not correct – Adjust chain tension.

4. Abrasive wear on some or all cutters due to striking stones or running in dirt – Sharpen or replace chain.

5. Depth gauges too high – Sharpen saw.

1. Cutter not sharpened properly – Sharpen saw or replace.

1. Chain tension too tight – Adjust chain tension.

2. Rails on guide bar pinched – Replace bar.

3. Clutch worn or damaged – Replace clutch.

4. Chain drive links damaged – Replace chain and drive sprocket.

1. Chain tension too loose – Adjust chain tension.

2. Worn guide bar – Replace guide bar.

3. Broken chain side link – Replace.

4. Worn drive sprocket – Replace.

1. Chain too loose – Check and adjust chain more often.

2. Tight joints due to burrs on bottom of links – Use more lubricating oil and sharpen chain more often.