Tohatsu M2.5A / M3.5A two-stroke (74.6 cc, no gear shift) service guide
Oil, gear oil, spark plugs and the service schedule for the Tohatsu M2.5A / M3.5A two-stroke (74.6 cc, no gear shift) (2.5 to 3.5 hp, two-stroke), from the factory service manual, plus how we service it in Hawaiʻi.
Models covered: Tohatsu M2.5A and M3.5A. Engine type WT47B, 1 cylinder, 74.6 cc (4.6 cu in), 2.5 PS and 3.5 PS, gasoline/oil mixture lubrication, water cooled with a rotary rubber impeller, recoil start, flywheel magneto, 1.4 L integral fuel tank, reduction 13:24, no gear shift (360 degree pivot turn). Maximum running speed M3.5A 4,300 to 5,000 rpm, M2.5A 3,800 to 5,200 rpm. Premix, no oil injection.
Quick answers
- What two-stroke oil does a Tohatsu M2.5A / M3.5A two-stroke use?
- Genuine engine oil or any NMMA certified TC-W3 two-cycle outboard oil.
- What is the fuel to oil ratio for a Tohatsu M2.5A / M3.5A two-stroke?
- 50:1 gasoline to oil. Running-in after an engine part has been changed: 20:1 for 10 hours; M 2-takt gives 25:1 for break-in.
- What gear oil does a Tohatsu M2.5A / M3.5A two-stroke use, and how much?
- TOHATSU gear oil (GL-5, SAE #80 to 90). Quantity: 90 cc.
- What spark plug does a Tohatsu M2.5A / M3.5A two-stroke use?
- NGK BP6HS-10 or Champion L87YC-10, qty 1. Gap: 0.9 to 1.0 mm.
- How often should a Tohatsu M2.5A / M3.5A two-stroke be serviced?
- The factory schedule lists: Initial 10 hours; Every 30 hours; Every 50 hours; Every 100 hours; Every 200 hours. In Hawaiʻi's salt water we do a full yearly service every 200 hours or 1 year, whichever comes first, and a new engine needs its first (break-in) service.
- When should the water pump impeller be replaced on a Tohatsu M2.5A / M3.5A two-stroke?
- The factory schedule says to replace it at 200 hours, and we follow that. In any case we never let it go longer than a year in Hawaiʻi's salt water.
- What is the idle speed of a Tohatsu M2.5A / M3.5A two-stroke?
- 1100 rpm in gear.
- What is the propeller nut torque on a Tohatsu M2.5A / M3.5A two-stroke?
- Held by a shear pin and split pin; no nut torque.
Maintenance specs
| Two-stroke oil | Genuine engine oil or any NMMA certified TC-W3 two-cycle outboard oil |
|---|---|
| Fuel to oil mix | 50:1 gasoline to oil. Running-in after an engine part has been changed: 20:1 for 10 hours; M 2-takt gives 25:1 for break-in |
| Gear oil | TOHATSU gear oil (GL-5, SAE #80 to 90) |
| Gear oil quantity | 90 cc |
| Gear oil lubricating port plug and drain oil port plug | 2 ports named on the bearing housing (lubricating port, drain oil port). |
| Spark plug | NGK BP6HS-10 or Champion L87YC-10, qty 1 |
| Spark plug gap | 0.9 to 1.0 mm. |
| Spark plug torque | 2.5 to 3.0 kg-m |
| Idle speed | 1100 rpm in gear |
| Anodes | Engine anode: check for wear. Gearcase anode: check for wear and deformation; the gearcase trim tab is used as the anode. Replace as required |
| Propeller | Held by a shear pin and split pin; no nut torque |
Service schedule
The factory maintenance intervals, with what is replaced and what is checked at each. Rows marked Hawaiʻi are our shop's yearly service for salt water use.
Initial 10 hours
Replace: gear case oil, gear case plug gaskets
Every 30 hours
Replace: gear case plug gaskets
Check: spark plugs
Every 50 hours
Replace: gear case plug gaskets, propeller cotter pin
Check: gear case oil
Every 100 hours
Replace: gear case plug gaskets, propeller cotter pin
Check: gear case oil, water pump impeller, anodes
Every 200 hours
Replace: gear case oil, gear case plug gaskets, propeller cotter pin, water pump impeller
Check: anodes
Source: Tohatsu M2.5A/M3.5A service manual, AUG 1988. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.