Resistance to rotating the engine

This is probably a dumb question, and yes, I am undoubtedly being overly cautious. Now that I have mounted the prop, I have to rotate the engine to set up the spinner on Page 47-04. At first when I turned it in either direction there was a lot of resistance, and a whirring noise. After rotating the engine in the "right" direction a few revolutions the going got easier and the noise disappeared, in that direction. However, if I try to rotate the engine in the reverse direction I still get the resistance and the noise. I theorize that this has something to do with the starter, but I need someone to pat me on the head and tell me this is normal!

Yes, the lower plugs are out.

Comments?

I think you are right

Sounds a lot like the starter was engaged. If you had turned it over with the starter that could easily have been what your were feeling and hearing. Next time look and see if the starter gear was engaged.

Rotax rotation

only turn the prop forwards so it will screw into the air in front of your plane. Turning it backwards is bad for the gearbox and verboten.

I'm going to try refreshing this thread to see if I can get someone with some Rotax experience to tell me why the engine turns over so hard. Coming from the background of Lycoming engines that turn over easily with the plugs out, I find it hard to figure out why it is so hard to turn this engine over with the prop, and if the gear noises I am hearing are normal.

It would also be great if someone could explain the starter mechanism to me. It obviously doesn't have a bendix drive. Does the sprag clutch engage if you try to turn the prop backwards, and is that what causes the extra resistance and whirring noise?

Mechanical disadvantage

The gear box gives the engine a mechanical advantage turning the prop. For each revolution of the engine, the prop only turns one half of a revolution. That makes it easier for the engine to turn the prop. When the prop is turned one revolution by hand, the engine must go around 2 times. That makes it twice as hard to turn the prop compared to a direct drive engine. Additional force is also required to overcome the friction of the gears. I do not know why the prop is not supposed to be turned backwards. Perhaps someone will explain that.
Another concern that I have is that the plans tell you to turn the prop before telling you to put oil in the engine. Although there is some residual oil from when the factory ran the engine, I would feel better if the engine was full of oil. But I could not find any opening on top of the engine to pour oil into. LOL I squirted some oil into the spark plug holes because I imagined pistons scraping cylinder walls.
Joe

The whiring noise you hear when you spin the engine "backwards" is the sprag spinning the starter motor ( it is a one way clutch). This is normal. The reason for not spinning the motor backwards is that you will literally suck the oil out of the hydralic lifters and collapse them in some cases and also put air in the oiling system. 1/4 or half turns back wards are no big deal but spinning the engine backwards has issues. This is no different than if you spin a small block chevy engine backwards, it will do the same thing. Finnaly the motor is stiff because it is a tight motor by design (slightly less than .001 cylinder wall clearance on the new ones) and it is high compression. After it runs for 10 hours or so like most engines it will free up.

Thank you guys for those great explanations. I now have a much better understanding of what I am dealing with. I too, wondered about rotating the engine without oil in it, as you are required to do for checking the timing coil clearances and adjusting the spinner. I guess it's too late now to worry about it, as I have already done it. Squirting in some oil does sound like a good idea though.