what dirk describes is correct. It does have a centrifugal clutch. I used to own one - and found that if it needed some significant throttle to get it started (e.g. if it had been on the wrong side and oiled up the plugs etc, or if it was very cold) that it would tend to spin the prop with the resulting forward thrust. If it was running/starting well then with the throttle minimised it would not spin the prop.
I have a manual but it contains nothing you can't sus in 5 minutes use. Two things to watch. If the fuel lever is left in the on position with the engine tilted up for a lengthy period of time, it's possible for the fuel tank contents to end up in the engine sump. Don't ask me how i know. The second thing is the ability of the engine to just about break your fingers if you're not firm with your starting pull. You wouldn't imagine a wee 2hp engine could do this but it can and does. The ignition timing is fixed and it's more than 20 degrees advanced. If you don't pull smartly on the starter cord, it's possible for the engine to fire and attempt to run backwards. This of course pulls the starter cord back into the engine with the consequent tug on one's fingers. It fekkin hurts.
JK - thanks for explaining the engineering cause behind my pain!
My only observation on maintainence would be that when refilling/topping up the oil you need to be very sure its level. If it is not absolutely level and you overfil it people with think its a two-stroke based on the smoke... although this did prove an effective way of dealing with midges at tignhabruich a few years ago!
