These bikes carry the engine oil in its own tank and pump it in. The brief’s cooling-and-oil guide is the water pump, the thermostat, the oil pump and the feed lines, plus the habit of warming the engine before you use it. Haynes 4298 does not name a two-stroke oil grade or a premix ratio. Beyond MCN’s “premium two-stroke oil”, the grade is Not published.

Warm it up

MCN’s figure, via the brief, is 60°C before hard riding. That is a riding rule. Haynes 4298 says the thermostat begins to open at 70–75°C, with a maximum valve lift of 3.3 mm at 90°C. Those are different facts. Use the dash if it works. On an Extrema the temperature gauge is analogue. On the round-light bike it is digital, and the brief says old clocks fail, so a dead gauge is not proof the engine is cold. A separate thermometer on the head, used carefully, is better than a guess. The sensor location is To verify.

A cold seizure is how fresh top ends die. The warm-up is the cheap part of guide 3.

Coolant

Drain into a tray, not onto the drive. The mix is half distilled water and half ethylene glycol antifreeze sold for aluminium engines, about 0.9 litres. Read the cap as well. Silicate and non-silicate coolants are not a detail to improvise. Look at what came out. A rusty brown system wants a flush. A creamy film wants a reason: a failed head O-ring or a leak between oil and water. Do not flush that and refill as if it were dirt.

The pump seal weeps down a tell-tale on many motorcycle pumps. Whether this engine has that hole is To verify. If you find a hole and it is wet, the seal is the part, not a tighter hose clip. Impeller condition and the weep specification are in the manual.

Bleed the system with the front higher than the head if the manual says so, and with the bleed screw the manual names. A pocket of air at the pump is a hot-running engine with a full tank. The procedure is To verify.

Oil pump and lines

Find the tank, the pump and every clear line between them. Cracked lines, at the banjo and where they rub the frame, are the usual leak. Clips that have cut into the pipe need a new pipe, not a tighter clip on the same cut.

Hartrusion’s oil-pump page says the 123 pump is stamped 08 and the 122 pump is stamped 33. They are not interchangeable. The same page calculates about one pump stroke every 50 crank revolutions, and at idle a small shot about every 3–5 seconds. The handbooks it quotes give 0.9% to 2% on the older 123 and 1% to 3% on the 122. That range moves with rpm and with the twistgrip. It is not a premix ratio you pour.

Confirm the pump delivers before you ride a rebuilt engine. If you cannot see oil move, do not “take it gently”. You will seize it gently.

If the pump has been dry, or the tank has been empty, fill it with a premium two-stroke oil — that much is the MCN advice — and bleed at the small screw until the oil runs without air, which is the method Hartrusion describes. A remembered 50:1 or 33:1 from another marque is not a setting. The cable adjustment that sets the stroke is still To verify if the pump has been apart.

Check the tank at the same time as the petrol. The bike will run with no oil in the tank until it does not run at all.

After the first heat cycle

When it has reached temperature, let it cool and recheck the level in the header tank, the hose clips, and the oil lines. A new base gasket that weeps coolant is a top-end problem, not a radiator problem. Oil-pump cover bolts are 3 Nm. The water-pump mounting bolt is 5 Nm. Coolant-hose banjo torque is Not published.