TractorData.com Yanmar YM2210 tractor engine information
YM2210
Yanmar 2T90
2-cylinder
69.9 ci
1.1 L
Bore/Stroke: 3.54x3.54 inches
90 x 90 mm
21.7 hp
Rated RPM: 2600
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TractorData.com Yanmar YM2000 tractor engine information
YM2000
Yanmar 2TR20
2-cylinder
69.9 ci
1.1 L
Bore/Stroke: 3.54x3.54 inches
90 x 90 mm
20 hp
Rated RPM: 2400
Some math:
20 hp x 2600 rpm / 2400 rpm = 21.66666 (YM2210 hp. Same torque but at higher rpm. Torque x rpm = hp)
My opinion - YM2210 is a near identical engine to YM2000 (many parts interchangeable) but rated at higher rpm.
Maybe Yanmar felt that design could be pushed more and still be as reliable.