Tecumseh SPECTRA 37 Service And Repair Manual
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Tecumseh SPECTRA 37 Service And Repair Manual

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For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983
A. FOREWORD
This manual contains information required to service or
repair all Tecumseh Italian built engines.
For exploded views of particular engines or component
part numbers, refer to the Tecnamotor and Tecumseh
Europa Spare Parts Catalogue.
When ordering spares from your authorized Tecumseh
Dealer, please quote the entire model and specification
number. These numbers are stamped on the engine as
shown below.
Always insist on genuine Tecumseh replacement parts.
ENGINE CODE
SPECTRA 37
E-38000
BH 37
E-45040E SER 5 074 C
MV 100 S
E-16000C SER 5 074 C
SER 5 174 A
S
S
174
S
174
www.mymowerparts.com
SPECT RA 37
E-38000
BH 37
E-45040E SER 5 174 C
MV 100 S
E-16000C SER 5 174 C
2
S
SER 5 174 A
S
S

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Mike Main
June 17, 2025

Fuel mix for an 0ld Flymo MV 100S, pleaase. 1: 25?????

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Summary of Contents for Tecumseh SPECTRA 37

  • Page 1 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 A. FOREWORD This manual contains information required to service or repair all Tecumseh Italian built engines. For exploded views of particular engines or component part numbers, refer to the Tecnamotor and Tecumseh Europa Spare Parts Catalogue.
  • Page 2 SERVICE BULLETIN Subject: 2-stroke engines - running in and oil requirements Tecumseh now requires that all 2-stroke engines with a recommended fuel/oil mix greater than 25 : 1 should be run with the first tank of fuel mixed at double the recommended ratio.
  • Page 3 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 B. CHECK-UP BEFORE REPAIR 1. GENERAL If a customer complains of an engine “non-starting”, it is a good rule to make an accurate check by first pulling the starter to ensure that there are no internal breakages.
  • Page 4 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 2. RECOIL STARTER (CHOKE) a - Move control lever (Fig 2) on engine or remote control (Fig 2) on equipment to choke or start. b - Operate mower control to release engine brake (if any).
  • Page 5 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 RECOIL STARTER (PRIMER FIXED SPEED) a - Push primer (Fig 2.1) three (3) times. Wait about two (2) seconds between each push. In cold weather (55°F/13°C or below) push five (5) times.
  • Page 6 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 COMPRESSION If compression is poor, check for: - Flywheel slipping on crankshaft. - Loose spark plug. - Loose cylinder head bolts. - Damaged cylinder head. - Warped cylinder head. - Insufficient tappet clearance (4-stroke engines).
  • Page 7 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 NOTE - On 2-stroke engines a broken or damaged reed plate will prevent starting. EQUIPMENT What may initially appear to be an engine fault, such as a starting difficulty or engine vibration, may possibly be the fault of the equipment rather than the engine.
  • Page 8 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 C. STARTER NON-STYLIZED STARTERS LAV - BV - BVS - VANTAGE - HBL - BH - AV - 1. RECOIL STARTER In the event of starter failure, remove the unit from the...
  • Page 9 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 To reassemble starter - Accurately position spring container on pulley (Fig 5). - Reposition the pulley assembly into container lubricating shaft and bushing of plastic pulley. Fig. 5 Spring Engagement Spring Disengagement - Refit retainer spring, place dog and brake spring in position (Fig 6).
  • Page 10 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 Disassembly Disassemble starter as follows. Refer to Fig 9. - Release main spring tension (5) by removing the handle and sliding the rope (12) out of the rope clip (16). (Fig 10).
  • Page 11 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 Reassembling - Refit gear (7) on pulley (6). - Wind the rope onto the pulley and fit the gear and pulley assy onto the bracket pin (11). - Secure the assy with spring hub (4) and screw (3) (Fig 14).
  • Page 12 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 SIDE MOUNTED STARTER VERTICAL ENGA- GEMENT USA TYPE NOTA - Alternative type starter above may also be fitted. Disassembly: - Before dismantling, the recoil spring must be locked by inserting pin C. (Fig 20).
  • Page 13 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 Assembly - To fit new rope, thread end through hole in gear and knot. - Rewind rope as per Fig 24. - Place spring on gear and preload two turns. Lock by inserting locking pin.
  • Page 14 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 4. A - STYLIZED RECOIL STARTER (Fig 28-A) VANTAGE, PRISMA, SYNERGY, BH, SPECTRA & FUTURA B - INTEGRAL RECOIL STARTER (Fig 28-B) VANTAGE & PRISMA Index Figs 28A & 28B. Retaining Pin...
  • Page 15 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 C - STYLISED STARTER WITH PLASTIC WEDGE (Fig. 28-C) This starter is similar to previous ‘Stylised’ starters except that the Pawl Retainer (2) is now plastic, and has extended lugs which pass through the starter and hold the assembly together.
  • Page 16 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 5. 12 VOLT ELECTRIC START SYSTEM ELECTRICAL CIRCUIT (Fig 29) Charging Alternator Alternator Lead Ignition Cut-out Lead Battery Earth Cable Alternator Lead, Red, 18AWG Alternator Lead (see 2) Connector Body Electric Starter Lead...
  • Page 17 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 Maintenance instructions for sealed batteries - Store battery in dry and ventilated area, disconnecting the battery from the wiring harnesses. - Avoid storing discharged batteries. It is extremely important that it is fully charged before storing.
  • Page 18 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 STARTER MOTOR TROUBLESHOOTING STARTERS STARTER DOES NOT FUNCTION Check for: - No current to the starter caused by faulty connections or dead battery. - Faulty safety switches, ignition or starter switch or solenoid.
  • Page 19 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 Re-torque starter mounting bolts to 80÷90 inch lbs (9.0÷10 Nm). NOTE - If it is necessary to replace either the starter pinion and/or the flywheel due to damaged teeth, it is essential that the starter pinion to flywheel ring gear mesh is checked on re-assembly.
  • Page 20 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 D. FLYWHEEL BRAKE SYSTEM Tecumseh's Flywheel Brake System provides consumer safety by shutting down the engine and lawnmower blade within seconds after the operator releases the engine/ blade control at the handle of the lawnmower.
  • Page 21 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 FLYWHEEL REASSEMBLY (Fig 5) 1. Brake lever compressed with alignment pin in place. Inspect brake pad (A) to be free of dirt, oil or grease. If pad is contaminated, or less than 1.5 mm (.060”) at narrowest point, replace.
  • Page 22 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 E. IGNITION SYSTEM GENERAL Two types of ignition systems have been used: - CONVENTIONAL IGNITION SYSTEM consisting of flywheel with built in magnets, ignition coil, condenser and breaker points. Depending on the model and year of production, the configuration will vary but service on these systems is identical.
  • Page 23 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 The standard method of flywheel removal used on other engines can damage the main bearing ball races. In order to remove the flywheel in the correct way, proceed as follows: - Remove the other parts in the standard way (air shroud, flywheel nut, starter cup etc.)
  • Page 24 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 Cleaning points To clean the points in position: - Rotate engine until points are open. Insert a piece of smooth emery. - Close points in order to grip emery and clean.
  • Page 25 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 CONDENSER CHECKING: - Check for external damage - Check condenser efficiency with tester. CONDENSER REPLACEMENT (Fig 14). - Unsolder wire from terminal ‘A’ - Remove wire from hole ‘B’. - Remove condenser securing screw ‘D’.
  • Page 26 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 3. IGNITION TIMING GENERAL All engines are correctly timed before delivery and the timing marked as in Fig 19 (Points Ignition). On engines with outside coil and solid state, ignition timing is fixed.
  • Page 27 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 4. SOLID STATE IGNITION SYSTEM (CDI) BVS - VANTAGE - PRISMA - SYNERGY - HTL - SPECTRA - FUTURA - BH - MV This is an all electronic ignition system with all the components sealed in a module and is located outside the flywheel.
  • Page 28 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 4A. GROUND TO GO IGNITION UNIT (FLYMO MV100S) Some Flymo Pilot machines (L47) have been built with an electronic ignition unit which operates the opposite way to conventional units. This unit has to be earthed to start the engine and can be identified by a green collar at the base of the High Tension lead.
  • Page 29 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 4-STROKE ENGINE SPARK ADVANCE WITH SPARK IGNITION SPARK ADVANCE TOP DEAD CENTRE ENGINE P.M.S. mm P.M.S. inch LAV-LAVR 30-35 1.070 - 1.770 3/64 - 1/16 LAV-LAVR 40-172 0.635 - 1.143 1/32 - 3/64 H 22 - 25 - 30 1.070 - 1.770...
  • Page 30 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 2-STROKE ENGINE SPARK ADVANCE ADVANCE TOP DEAD CENTRE ENGINE P.M.S. mm P.M.S. inch 3.09 - 3.75 1/8 - 9/64 TA MARINO 3.99 - 4.48 5/32 - 11/64 3.02 - 3.70 1/8 - 9/64 VA MARINO 4.05 - 4.55...
  • Page 31 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 F. AIR FILTERS GENERAL Owing to the nature of the work for which an air cleaner is designed, it follows that it must have a direct effect on the carburation. It is, therefore, essential that it is kept perfectly clean and correctly maintained at all times.
  • Page 32 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 2. MUFFLER ON POLYURETHANE AIR CLEANER The intake muffler is fitted on the standard polyurethane air cleaner. The cover has been modified by adding 3 holes (Fig 2) in order to secure the muffler by means of 3 self-threading screws.
  • Page 33 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 4. CLEAN.ASP.AIR LAV ENGINES As illustrated in Fig 6, reverse flow air is taken from the flywheel fan so that by centrifugal effect, all dirt and dust and particles are removed from the intake pipe area.
  • Page 34 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 6. AIR CLEANER FOR FLYMO Two stroke engines fitted to Flymo Airborne Rotary lawnmowers (Hover mowers) are equipped with a “Turbo” air filter of Flymo design and origin. Parts for these filters should be obtained from your usual Flymo stockist.
  • Page 35 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 7. DUAL POLYURETHANE AIR CLEANER WITH SNORKEL (Fig. 11) OPERATION Similar to polyurethane air cleaner with paper element and snorkel except in this instance there are two polyurethane filters. One filter element is located in a housing before the...
  • Page 36 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 HORIZONTAL CRANKSHAFT ENGINES - Loosen the two cover screws completely and remove cover from base (Fig 12) - Remove complete air cleaning lifting and softly rotating the cartridge, being careful to prevent dirt from entering air intake.
  • Page 37 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 9. AIR CLEANER WITH AIR INTAKE FROM THE BLOWER HOUSING Fig. 14 Filter Cover Screws Filter Element Foam Gasket Foam Support Base Breather Gas Recirculation Filter Proceed as follows: 1. Remove filter body by unscrewing the two screws.
  • Page 38 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 10. AIR CLEANER INVERTED FLUX FOAM TYPE Fig. 15 Filter Cover Retaining Lugs Filter Element Foam Gasket Base CHECK PROCEDURE Check the filter annually, or every 25 hours of use. More frequently if used in dusty environments.
  • Page 39 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 11. CONICAL AIR CLEANER Fig. 16 Cover Filter Element Flange Location Tab Location Slot Retainer PAPER CARTRIDGE REPLACEMENT 1. Turn cover to the left (counter-clockwise) and remove it and filter from flange. Discard filter.
  • Page 40 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 G. CARBURETTORS 1. GENERAL Two basic types of carburettor are fitted to Tecumseh engines built in Italy. - Diaphragm carburettor - Float carburettor The operating and constructional differences of these types of carburettor are as follows: DIAPHRAGM CARBURETTOR (Fig.
  • Page 41 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 FLOAT TYPE CARBURETTOR (FIG. 2) E - Choke F - Idle G - Intermediate speed H - Full load Inlet of petrol to the carburettor is controlled by needle P. When the petrol level decreases, the float G falls and consequently the needle allows petrol to flow in and restore the level.
  • Page 42 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 2. DIAPHRAGM CARBURETTOR There are 2 types of diaphragm carburettor : - Standard carburettor - Carburettor with primer ADJUSTMENT OF DIAPHRAGM CARBURETTOR For carburettors with variable main and idle jets, proceed as follows (see Fig 3).
  • Page 43 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 SERVICING DIAPHRAGM CARBURETTOR Standard diaphragm carburettor To clean carburettor (Fig 5), proceed as follows: - Remove main jet (nos. 14, 15, 16, 17) and idle jet (nos. 10, 11, 12, 13). Check these for serviceability, replace worn or damaged jets.
  • Page 44 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 d) DIAPHRAGM CARBURETTOR WITH PRIMER The carburettor with primer is characterised by the absence of a choke and by the presence of a special rubber pump, connected to the carburettor base cover by means of a rubber tube (Fig 8).
  • Page 45 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 BALL TYPE NON RETURN VALVE (FIG 12) The brass valve, pressed into the carburettor body has been discontinued. The current non return valve consists of a steel ball which seats in a taper situated in the fuel inlet elbow.
  • Page 46 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 b) OPERATIONS ON FLOAT CARBURETTORS Removal and disassembly of the carburettor - Remove air cleaner. - Disconnect fuel pipe. Empty fuel bowl by means of the push button (f - Fig 14).
  • Page 47 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 Plastic (white) floats If the carburettor is fitted with a white plastic float, the distance ‘L’ (Fig 16) is pre-set and non adjustable. If this setting is not correct, or float is damaged, a new float must be fitted.
  • Page 48 The proper float height is very important to all Tecumseh carburettors and must be set by using the Tecumseh float setting tool part number 670253A. (Fig 23) - Brass floats only.
  • Page 49 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 d) ALTERNATIVE STYLE PRIMER START FLOAT CARBURETTORS (Fig. 26) With the advent of more stringent emission controls, carburettor technology is continually improving. Be aware that there are now many different types of Primer Carburettors, which at first glance may seem similar.
  • Page 50 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 H. GOVERNORS GENERAL Engines currently fitted to lawnmowers, pumps etc, are generally fitted with a speed governor which controls the engine revolutions at a predetermined speed under varying load conditions. TWO STROKE ENGINES Two stroke engines are usually fitted with pneumatic governors.
  • Page 51 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 GOVERNORS FOR AV AND MV MODELS AV and MV engines are fitted with a pneumatic governor similar to the one already used on the previous TA and VA engines. For the speed control on the governor for AV and MV engines, there is an adjusting screw for use on variable speed engines.
  • Page 52 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 2. MECHANICAL GOVERNORS FOR FOUR STROKE ENGINES GENERAL All four stroke engines are fitted with centrifugal type governor (Fig 8). This consists of a plastic gear «A» which is caused to rotate by the camshaft gear.
  • Page 53 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 3. GOVERNOR LINKAGE HORIZONTAL CRANKSHAFT ENGINES (HBL-BHK-BHT & P VERSIONS) DESCRIPTION AND ADJUSTMENT (Fig. 10) The link (B) positively connects the lever (E) with the governor lever (A). The link (C) connects the lever (E) with the main throttle lever (D).
  • Page 54 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 4. GOVERNOR LINKAGE FOR HBP/G AND BHG ENGINES DESCRIPTION On above engines the position of the carburettor is different and therefore small changes on the governor linkage are necessary. BHG & HBP/G engines are mainly used on generators and therefore usually run with fixed speed at 3.000 rpm.
  • Page 55 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 5. GOVERNOR LINKAGE FOR FOUR STROKE ENGINES WITH VERTICAL CRANKSHAFT DESCRIPTION Link (T) positively connects lever (A) with main throttle lever (F). (Fig 15). With the engine running the governor rod (R) rotates...
  • Page 56 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 d) NEW GOVERNOR LEVER AND CLAMP WITH PHILLIPS HEAD. LEFT HAND THREAD ON 4- STROKE VERTICAL SHAFT ENGINES Starting from serial No. 3-307 D a new clamp No. 27410096 and a new left hand thread screw No. 2919157 have been introduced.
  • Page 57 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 HIGH SPEED CATEGORIES Figs 22 and 23 show the position of the governor spring for different speeds. The choke carburettor (Fig 22) is using the spring 27920010. For tiller version the spring is mounted on the 3rd hole.
  • Page 58 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 I. TWO-STROKE MECHANICAL EN- GINE PARTS 1. UNIBLOCK ENGINES (AV520-600-750-125) INTRODUCTION Fig. 1 shows the short block. Fig. 2 shows an exploded view of the engine. As may be seen the momoblock is compact (combined crankcase and cylinder) and it is sealed in the upper part by the shroud mounting base.
  • Page 59 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 Inspection of seals Fig 4 shows the points to which are fitted the gaskets and oil seals that must always be checked to ensure good running of the engine. On a 2 stroke engine all the seals are very important for correct operation.
  • Page 60 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 - Remove the crankshaft taking care not to lose the 29 needles of the bottom main bearing. The engine is now completely disassembled. Check bore for cylinder wear and ovality. This should not exceed 0.10 mm or 0.0039"...
  • Page 61 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 d) MAIN BEARING The needle bearings can be replaced using Tecumseh tools (Fig 10). Use tool 88841026 for flywheel side and tool 88841027 for PTO side to remove bearings. To refit bearings use tool 88841530 for flywheel side and tool 88841529 for PTO side.
  • Page 62 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 OVERSIZED PISTONS FOR 2 STROKE ENGINES As in all engine production, Tecumseh occasionally pro- duce cylinders bored above maximum allowable tolerance. In this case .010” oversize pistons and rings will be fitted.
  • Page 63 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 b) REMOVAL OF FLYWHEEL The standard method of flywheel removal used on other engines can damage the balls and bearing tracks (Fig 16). In order to remove the flywheel in the correct...
  • Page 64 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 d) REMOVAL AND REFITTING OF CONNECTING ROD & PISTON ASSEMBLY This procedure is the same as for earlier engines. REMOVAL AND REFITTING OF CRANKSHAFT (INCLUDING BALL BEARING) - In order to remove or replace the bearing, the shroud base must be pre-heated to 80/100 deg C.
  • Page 65 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 3. ALTERNATIVE VERSIONS (AV85S, EARLIER MV100S). For a short period, alternative versions to the two previously mentioned were built. Some versions had a top main ball bearing, bottom bush bearing and bushed connecting rod bearing.
  • Page 66 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 2 - STROKE ENGINE - SPECIFICATIONS AV 125 MV 100 S MV 100 SB HIGH RPM DESCRIPTION Inch Inch Inch Engine displacement 123.19 cu.Inch 7.5 cm 98.49 cu.Inch 6.01 cm 98.49 cu.Inch 6.01 Stroke 50.15...
  • Page 67 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 2-STROKE ENGINE -SPECIFICATIONS AV 125 MV 100 S MV 100 SB High RPM DESCRIPTION Inch Inch Inch Conrod bearing diam. - 17.450 .6870 – – – – piston pin side 17.475 .6879...
  • Page 68 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 2-STROKE ENGINES PRODUCED FROM 1985/86 TO PRESENT 2-STROKE ENGINE SPECIFICATIONS Inch DESCRIPTION MV 100 MV 100 MV 100-S MV 100.S 53.061 2.089 Boring 53.086 2.090 Stroke 44.5 1.752 Engine displacement cu. inch.
  • Page 69 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 2-STROKE ENGINES PRODUCED FROM 1985/86 TO PRESENT 2-STROKE ENGINE SPECIFICATIONS Inch DESCRIPTION MV 100 MV 100 MV 100-S MV 100.S Crankshaft bearing seat diam. - 25.400 1.0000 power intake side 25.387 .9994...
  • Page 70 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 2-STROKE ENGINE CLOSING TORQUE SPECIFICATIONS AV-MV TYPE ENGINES DESCRIPTION SCREW N x m Inch x Lbs SIZES 100S Cylinder head screw 1/4-20 x 18 10.1 - 11.28 1.029 - 1.15 90 - 100 Conrod screw 10-24 x 19.05 6.77 - 7.41 0.69 - 0.75...
  • Page 71 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 L. MECHANICAL PARTS OF 4 STROKE ENGINES 1. GENERAL The engine block/assemblies supplied for the vertical shaft and horizontal shaft engines are similar in construction (apart from mounting differences). The disassembly and inspection of these is therefore almost the same.
  • Page 72 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 If seats are beyond repair, it is necessary to change the complete cylinder as the seats are not replaceable. Check the valve seats for pitting etc, the valves are marked ‘E’ (exhaust) and ‘I’ (inlet). If the valve guides are worn, valves with oversize stems are available and the guides should be reamed out to take these.
  • Page 73 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 NOTE - Early type valves were secured by a pin fitted through a hole in the valve stem and secured by the spring cap. This type can be removed by lifting the spring and removing the pin with a pair of long nosed pliers (Fig 8).
  • Page 74 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 b) ENGINES HTB-HCB-HSB-HBP-BH WITH BALL BEARING ON PTO These engines are fitted with a ball race at the PTO end of the crankshaft and removal is as follows: Remove crankshaft key and any dirt or rust present on the shaft.
  • Page 75 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 5. INTERNAL INSPECTION CYLINDER Check with suitable instruments the wear on the following: Cylinder bore (Fig 14-A) (Fig 14). This should not exceed 0,15 mm (.006”). Ovality should also not exceed 0,15 mm (.006”). (See table for piston sizes).
  • Page 76 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 d) CONNECTING RODS (Fig. 17) Different types of conrods are fitted to the different engines. Some characteristics are common. All conrods have match marks which must always be assembled together and when fitted onto the engine the marks must face outwards (towards the PTO).
  • Page 77 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 PISTON RINGS AND PIN Remove rings from piston and clean all carbon from ring grooves with the aid of a piece of old piston ring (Fig 21). Check piston for damage. Piston wear and ovality should not exceed 0,15 mm (.006”).
  • Page 78 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 Piston assembly (Figs 24 & 25) For reassembly purposes there is a match mark on the piston pin boss (A). Depending on the engine type pistons may have an off-set piston pin. This must be fitted towards the magneto side.
  • Page 79 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 CAMSHAFT Check gear and cams for damage or wear. Check that shaft is not bent and that bearing dimensions conform to sizes given in table. On vertical shaft engines check that oil passages are clear, replace shaft if necessary.
  • Page 80 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 g) LUBRICATION On vertical shaft engines, lubrication is provided by a positive displacement type pump (Fig 30) which forces oil to the top main bearing via a drilling in the camshaft and a gallery in the crankcase (Fig 31).
  • Page 81 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 Oleomatic Governor (Fig. 34) A plastic sleeve (A) is actuated by two centrifugal weights (D), the plastic sleeve moving along the centre spindle; the spindle (B) being drilled through the centre to allow oil to be drawn in under the head of the sleeve.
  • Page 82 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 Check the filter and replace if necessary. The valve breathes into a rubber pipe (Fig 38). This may be open to atmosphere (open type), or may be connected to the carburettor intake (closed type) (Fig 39).
  • Page 83 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 6. REASSEMBLY GENERAL Reassembly should be carried out in the following order. After thoroughly cleaning all parts, position crankcase on bench (Fig 42). If replacement of flywheel side oil seal is necessary refit at this point.
  • Page 84 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 OVERSIZED PISTONS FOR 4-STROKE ENGINES As in all engine production Tecumseh occasionally pro- duce cylinders bored above maximum allowable tolerance. In this case .010” oversize piston and rings will be fitted.
  • Page 85 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 PISTON AND CONNECTING ROD (FIG 49) Fit conrod to piston by first fitting one retainer ring, lubricate conrod and secure with piston pin (Fig 51). Fit second retaining ring, if rings have been renewed rub cylinder wall with fine emery to remove “glaze”...
  • Page 86 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 CAMSHAFT - OIL PUMP - COVER Position valve lifters in the correct order and fit camshaft with timing marks aligned as in Fig 55. Check governor shaft and replace if worn or bent.
  • Page 87 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 g) MOUNTING FLANGE FOR ENGINES WITH LATERAL PTO Reduction shaft service A retaining ring secures the 8,5 : 1 PTO shaft. The sequence of the washers is the most important factor to consider for reassembly.
  • Page 88 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 VALVE TRAIN SERVICE Remove the rocker arm cover. The cover is secured with four bolts that are 3/8" external hex or a Torx 30 internal (Fig 59,A). The gasket between the rocker arm cover and the head should always be changed when the cover is removed to ensure proper sealing.
  • Page 89 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 The condition of the valves and valve seats can be inspected at this time and serviced accordingly. (Fig 63) The all metal head gasket MUST be removed from the engine, and discarded (Fig 64). Always fit a new head gasket when Head is removed.
  • Page 90 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 When both valves have been installed back into the head, place a new head gasket into position and attach the cylinder head. (Fig 67). NOTE - The head gasket is coated. Any scratches or bending to the head gasket will require a new head gasket or leakage may occur.
  • Page 91 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 SETTING THE VALVE LASH To properly set valve lash on the OVRM engine make sure the engine is cold and at TOP DEAD CENTRE on the compression stroke (both valves are closed). The lash on both valves is 0.05-0.15 mm (.004") between the rocker...
  • Page 92 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 b) VALVE SERVICE Clean all parts and remove carbon from valve heads and stems. If valves are in usable condition, grind or cut the valve faces to 45 degrees angle using tools 26990002 and 26990001.
  • Page 93 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 4-STROKE ENGINE SPECIFICATIONS (BV – BVL – VANTAGE – PRISMA – SYNERGY – PREMIER – SPECTRA – FUTURA) Engine displacement 63.500 63.500 66.675 71.425 70.993 63.500 66.675 70.993 Boring 63.525 63.525 66.700...
  • Page 94 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 4-STROKE ENGINE SPECIFICATIONS Engine displacement 63.500 66.675 70.993 Boring 63.525 66.700 71.018 Stroke 47.1 49.2 49.2 Advance (P.M.S.)FIXED Coil-flywheel air gap 0.30 0.30 Distance between electrodes 0.60 0.60 and spark plugs 0.70...
  • Page 95 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 4-STROKE ENGINE CLOSING TORQUES (BV-BVL-BVS-VANTAGE-PRISMA-SYNERGY- PREMIER-SPECTRA-FUTURA) DESCRIPTION Screw N x m Inch x Lbs SIZE Conrod fastening screws 1/4 - 20 10.10 ÷ 11.28 90 ÷ 100 Oil drainage cap 5/8 - 18 13.5 ÷...
  • Page 96 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 4-STROKE ENGINE CLOSING TORQUES BH ALL TYPES DESCRIPTION Screw N x m Inch x Lbs SIZE Conrod fastening screw 1/4 - 20 10.10 ÷ 11.28 90 ÷ 100 Oil drainage cap 1/4 - 18 6.8 ÷...
  • Page 97 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 M. TROUBLESHOOTING This section is designed to help the repairer identify the engine fault and perform the necessary repair. The main symptoms of defective engines are listed below. The numbers listed under each defect indicate the causes and remedies contained in the following pages.
  • Page 98 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 EQUIPMENT TROUBLE CHAPTER 1 SYMPTOM CAUSE DEFECT REMEDY 1) 2) 3) 1) 2) 3) Engine does not The remote control The starter throttle is not completely closed, Adjustment of ends start or is slow in...
  • Page 99 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 EQUIPMENT TROUBLE CHAPTER 1 SYMPTOM CAUSE DEFECT REMEDY The machine vibra- Blade unba- Blade balancing is more important than its Blade balancing. tes. lanceds. Engine to sharpness. An unbalanced blade causes early Bolt tightening.
  • Page 100 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 ENGINE – POWER SUPPLY UNIT TROUBLE CHAPTER 2 SYMPTOM CAUSE DEFECT REMEDY The engine starts fuel tank Insufficient fuel flow. This problem result in the If clogged, it will be up and stops after cap’s breather is...
  • Page 101 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 TROUBLE CAUSED BY ENGINE – POWER SUPPLY UNIT CHAPTER 2 SYMPTOM CAUSE DEFECT REMEDY Engine runs irre- Air is drawn inside Air may drawn in through the parts that connect Replace defective or gularly at no-load or carburettor.
  • Page 102 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 TROUBLE CAUSED BY ENGINE – IGNITION UNIT CHAPTER 3 SYMPTOM CAUSE DEFECT REMEDY Engine does not Spark plug is lacking Spark plug. Spark plug hood not connected Makes sure that the start.
  • Page 103 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 TROUBLE CAUSED BY ENGINE – ELECTRIC STARTER UNIT CHAPTER 4 SYMPTOM CAUSE DEFECT REMEDY Engine does not Battery worn out. If battery is below a certain charge, the engine Charge battery with start with E.S., starts...
  • Page 104 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 TROUBLE CAUSED BY ENGINE – MONOBLOCK ENGINE UNIT CHAPTER 5 SYMPTOM CAUSE DEFECT REMEDY Engine does not Excessive scaling The excessive scaling acts like a sponge, and Remove scaling. start or starts with...
  • Page 105 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 TROUBLE CAUSED BY ENGINE – MONOBLOCK ENGINE UNIT CHAPTER 5 SYMPTOM CAUSE DEFECT REMEDY Engine does not Broken conrod. Conrod breaks with seizure on crank journal Replace conrod. If start. It idles without = oil missing.
  • Page 106 This warranty supersedes all previous versions. WARRANTY DESCRIPTION Tecumseh Europe S.p.A. guarantees the repair or replacement, at its own discretion, to the original purchaser of each product or product part whose material and/or workmanship is found to be defective after inspection by one of its Authorized Servicing Centres or one of our Centralized Dealers, and also by Tecumseh Europe S.p.A.
  • Page 107 The Authorized Servicing Centre must perform small or medium repair work immediately. Defective parts must be kept at the disposal of Tecumseh Europe Turin until the file has been defined. Once the repair has been made, the duly filled out request for warranty, and the blue, white and pink copies, must be sent to the Centralized Dealer or to Tecumseh Europe Turin.

  • Page 108: Special Tools

    For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 SPECIAL TOOLS 88841027 670103 tool for disassembling roller flywheel removal bearings bolt 2-stroke power intake side shaft with 7/16” thread 670297 (*) 88841044 thickness gauge for 0.3 conveyor base removal mm flywheel air gap...
  • Page 109 For Discount Tecumseh Engine Parts Call 606-678-9623 or 606-561-4983 670169 (*) 670283 (*) flywheel removal bolt borer for increasing valve guides shaft with ½” thread all 4-stroke engines 670305 (*) 88841004 (*) flywheel locking belt tool for mounting compression rings...

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