HawaiiOutboard Repair
(808) 824-4380 Request service
MenuClose

Tohatsu M60B / M70B and M60C / M70C (3 cylinder, 938 cc, carbureted two-stroke) service guide

Oil, gear oil, spark plugs and the service schedule for the Tohatsu M60B / M70B and M60C / M70C (3 cylinder, 938 cc, carbureted two-stroke) (60 to 70 hp, two-stroke), from the factory service manual, plus how we service it in Hawaiʻi.

Models covered: M60B and M70B in the EF (option), EFO, EFTO (option), EPO and EPTO versions. 3 cylinders, 938 cc (57.2 cu in), bore 74 x stroke 72.7 mm, 3 carburetors, loop charged with reed valves; M60B 44.7 kW (60 ps) at 5,000 rpm, M70B 52.2 kW (70 ps) at 5,500 rpm, full speed range 4900 to 5600 rpm; gear ratio 13:23. EFO, EFTO, EPO and EPTO are auto mixing (oil injected, integral 2.6 liter tank)

Quick answers

What two-stroke oil does a Tohatsu M60B / M70B and M60C / M70C use?
Tohatsu 2-cycle engine oil Super Gold; if not available another marine maker's outboard oil with NMMA (BIA) certified TC-W or TC-WII. Do not mix brands or kinds of oil: it can gel and block the oil filter between the tank and the pump.
What is the fuel to oil ratio for a Tohatsu M60B / M70B and M60C / M70C?
Auto mixing: 50:1 at full throttle to 120:1 at trolling, set by the oil pump. EF models: 50:1, and 25:1 during breaking-in. A new auto mixing engine also gets a 50:1 mix in the fuel tank on top of the oil in the oil tank.
What gear oil does a Tohatsu M60B / M70B and M60C / M70C use, and how much?
Tohatsu gear oil. Quantity: M60B / M70B: approx. 700 cc. M60C / M70C: approx. 900 mL (30 US fl oz).
What spark plug does a Tohatsu M60B / M70B and M60C / M70C use?
NGK B8HS-10 or Champion L78C, qty 3. Gap: 1 mm; correct to 0.9 to 1.0 mm (0.0354 to 0.0397 in); repair limit 1.2 mm (0.0472 in) or greater.
How often should a Tohatsu M60B / M70B and M60C / M70C be serviced?
The factory schedule lists: Initial 10 hours or 2 weeks; Every 30 hours or 1 month; Every 50 hours or 3 months; Every 100 hours or 6 months; Every 200 hours or once a year. 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 M60B / M70B and M60C / M70C?
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 M60B / M70B and M60C / M70C?
Pilot screw 1 1/2 ± 1/4 turns out (60C / 70C 1 3/8 ± 1/4).
What is the propeller nut torque on a Tohatsu M60B / M70B and M60C / M70C?
29.4 to 39.2 N·m (3.0 to 4.0 kg-m, 21.69 to 28.92 lb-ft).

Maintenance specs

Injection (two-stroke) oilTohatsu 2-cycle engine oil Super Gold; if not available another marine maker's outboard oil with NMMA (BIA) certified TC-W or TC-WII. Do not mix brands or kinds of oil: it can gel and block the oil filter between the tank and the pump
Fuel to oil ratioAuto mixing: 50:1 at full throttle to 120:1 at trolling, set by the oil pump. EF models: 50:1, and 25:1 during breaking-in. A new auto mixing engine also gets a 50:1 mix in the fuel tank on top of the oil in the oil tank
Oil tankIntegral tank, 2.6 liters. The oil level sensor (float switch) turns on with about 0.5 liter left: buzzer in the remote control box and lamp in the tachometer
Gear oilTohatsu gear oil
Gear oil quantityM60B / M70B: approx. 700 cc. M60C / M70C: approx. 900 mL (30 US fl oz)
Spark plugNGK B8HS-10 or Champion L78C, qty 3
Spark plug gap1 mm; correct to 0.9 to 1.0 mm (0.0354 to 0.0397 in); repair limit 1.2 mm (0.0472 in) or greater
Spark plug torque24.5 to 29.4 N·m (2.5 to 3.0 kg-m, 18.08 to 21.69 lb-ft)
Trolling / idle speedPilot screw 1 1/2 ± 1/4 turns out (60C / 70C 1 3/8 ± 1/4)
ThermostatStarts to open at 60 °C, opens fully at 70 °C; with pressure relief valve.
AnodesTrim tab, cylinder head and power trim and tilt anodes: replace when worn by 1/3 or more
Propeller nut29.4 to 39.2 N·m (3.0 to 4.0 kg-m, 21.69 to 28.92 lb-ft)
Power trim and tilt fluidAutomatic transmission fluid. Level at the oil plug hole with the engine tilted up and the piston rods fully extended; oil plug 2.94 to 4.9 N·m

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.

  1. Initial 10 hours or 2 weeks

    Replace: gear case oil, gear case plug gaskets, propeller cotter pin

    Check: spark plugs, fuel filter

  2. Every 30 hours or 1 month

    Replace: gear case plug gaskets

    Check: spark plugs, fuel filter, gear case oil

  3. Every 50 hours or 3 months

    Replace: gear case plug gaskets, propeller cotter pin

  4. Every 100 hours or 6 months

    Replace: gear case plug gaskets, propeller cotter pin

    Check: water pump impeller, thermostat, anodes

  5. Every 200 hours or once a year

    Replace: gear case oil, gear case plug gaskets, propeller cotter pin, water pump impeller

    Check: thermostat, anodes

Source: Tohatsu M60B/M70B service manual. Specs can change by model year and serial number, so always confirm your exact model from the serial tag on the clamp bracket.

Other Tohatsu guides