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Rotax Engines
Hirth Engines
   Hirth 2702-40HP
   Hirth 2703-55HP
   Hirth 3202-55HP
   Hirth 3203-65HP
   Hirth 3503-70HP
   Hirth F30 (80HP-110HP)
   Hirth F33-28HP
   Hirth F23-50HP
   Hirth 3701 84HP - 100HP
Engine Mount Kit

Note: Initial deliveries of 3500 series engines are scheduled to begin in December 2003. High Performance version of 60Hp 3502 - fuel efficient Engine The 3503 produces 70hp at 6500 rpm while building an impressive torque of 57 ft lbs. at 6000 rpm. Operating in an Rpm range 1500 Rpm higher than the 60Hp 3502 results in much more thrust at full power for vehicles requiring more climb capability than cruise power as the 3502 is designed for. Fuel rate is 30-40% less than competing brands of 2 cycle engines in the same Hp range. 3503 incorporates Al-Nikasil coated cylinders for superior performance and reliability. Al-Nikasil in simple terms is a nickel based material, applied in a paste form, when super heated it becomes part of the cylinder itself. Al-Nikasil provides for a super low coefficient of friction, reducing engine heat and wear. The combination of Nikasil cylinders with water cooling render these engines immune from cold seizure, shock cooling or seizure from high EGT conditions. The pistons and cylinders expand at the same rate thus providing for a seizure resistant environment. 3503 crankshaft is 4130 chrome molly steel. Heads, cylinders, rings, block casting, connecting rods and associated components are all of the highest grade alloys available. With optional vertically mounted fuel injection 3502/03 can be used in compact engine compartments. Mounting bolt pattern is identical to the R-582. Factory recommended TBO is rated at 1000 Hrs. @ 75% power.
Hirth 3503-70HP





Dual 34mm slide or optional electronic fuel injection

Engine Type:

2 cycle, two cylinder

Fuel Pump:

Auxiliary external pneumatic - 12VDC with fuel injection




Fuel mixed with oil @ 50:1 /Blue Max @100:1 or optional oil injection




Counter clockwise, viewed from output end




12 volt electric, recoil or both
250 watt/20 amp alternator standard




Water cooled.

HP Output:

70hp @ 6500rpm


79 lbs-not including radiator & coolant. Optional gearbox adds 19 lbs.


57ft/bs @ 6000rpm

Reduction Units:

G-50 gearbox available in 2.16:l, 2.29:l, 2.59:l, 3.16:l and 3.65:l ratios.


Dual CDI
(Capacitive digital Ign.)

Drive Coupling:

Elastomeric dampener or optional centrifugal clutch.