I think the R528F is just telling you that it doesn't want to be propped for those low rpm. With peak power at 32.8k rpm, the engine is obviously timed for high teens and up and I would think loading it down would produce mediocre performance results and some temperamental habits. It might run smooth but you're kinda chugging the sports car down the boulevard.
R528F
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Displacement: 4,66 cc
R.P.M. (max power): 32.800 RPM
Practical range: 2.000-38.400 R.P.M.
Bore x stroke: 18,35x17,60 mm
Sleeve: 3 ports
Rear ball bearings: steel
Front ball bearings: steel
Crankshaft: 14 mm
Carburetor: aluminium - 6,5mm - rotary
Glowplug: Standard Special (C6S)
Exhaust position: rear
Starting: -
Weight: 313 g
Fuel type: 10% nitro[/TD]
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