I think a 3 cylinder two stroke about 600cc for the early ones.
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And very smokey...
Skidders weigh many tonnes but seemingly go almost anywhere.....
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Those tires[biggrin] are PADDLES from a paddle steamer
Attachment 146759
3 cyc
550 two stroke
go any where I reckon
Mine was a soft top, on some tracks the only thing that kept it upright was the top of the roof, if you ddid get bogged you could pick them up, one end at at time. Jack up one back wheel and pull start them with a rope
cheers
blaze