Fuji the deisel engine as you more than likely know uses compression to ignite the mixture so no spark plugs.
The additional speed required is nothing to do with the internal friction of the beast which will be the same as a petrol.
It just requires more oomf to get it chuging away again. Its the same with bump starting cars drop the clutch on a deisel and its like hitting a wall as you fight against the compression. On a petrol you will get it going through a couple of compression cycles then it will fire up. Good thing about a deisel is that it usually goes when your through the first compression so you can start them in under a meter with the applance of brute force and sweat.
I have never flown one of these deisel suck squeeze bang blows but years driving lorrys etc I suspect thats the reason