Hi Mops,
What the Marking “K.MAR” Could Mean ,I don't have a definite answer.
It might be a manufacturer’s logo or batch code.
It could refer to a machining house, foundry, or part subcontractor, especially if the engine or crank was made under contract.
Sometimes crankshafts are remachined or replaced, and the new maker (or rebuilder) stamps their mark.
I didn’t find any documents having “K.MAR” associated with Victa or Hurricane engines
Why the Top End (Rotor Interface) Isn’t Fully Machined
Possible reasons:
It’s a generic crank not yet finished for that particular engine
The crank may be a “blank” or partially machined version. The final step of machining the taper, shoulder, or journal to exactly fit the rotor/flywheel may not have been done.
It’s intended for a different engine design
The crank might have been used for another engine with a different rotor diameter, taper, or mounting method. That would mean the rotor (from your suspected engine) doesn’t match exactly.
If this crank came from a “copy” engine or third‑party manufacturer, tolerances or specs might differ slightly.
machining error
Or perhaps someone attempted a rebuild and didn’t complete the machining step correctly.
Interchange part / retrofit adaptation
Sometimes people adapt a crank from a different model/engine and leave material so they can machine it to fit as needed. The extra material gives flexibility to fit different flywheels or rotors.
Back in Rotomo days there were copied Victa engines (that probably are slightly different) ,I've seen a lot of strange adaptions using what was once a Victa 2 stroke motor ,like old air compressors using an electric motor to spin the 2 stroke so the compression
cycle fills up the air tank.
Even old go-kart motors could have a lot of different parts that were made stronger for more Hp.
Cheers
Max.
