58 IRS LC – liquid-cooled single-cylinder engine

Design and Features

The engine cylinder is a casted from aluminum alloy with a galvanically applied hard working surface using nikasil technology. The piston is casted from an alloy with a high silicon content and has a groove for one piston ring made of special hardened cast iron. A special molybdenum sulfite coating is applied to the piston surface to reduce friction and extend engine life-time. The crankshaft made of alloyed steel is supported by two ball bearings, the connecting rod made of high-strength duralumin has both eyes mounted on needle roller bearings.

The engine is characterized above all by a very high power in the entire speed range and we can compare its performance with engines with a capacity of 70 - 80 cc. Of course, it is very easy to start in both cold and warm condition, excellent reliability and very low vibrations. Its weight stands at today's minimum of this range. The overall positive impression is enhanced by the modern design with blue anodized parts and perfect workmanship exclusively on CNC machines.

The preparation of the mixture is controlled by a Walbro carburettor with a choke and a diaphragm pump. The ignition is battery powered with  electronics and a microprocessor controlled ignition timing and with safety functions.

Technical Specification

Model 58 IRS, rear intake, carburettor, 2-stroke, 1-cylinder
Displacement 58 cm3
Air/Water-cooled ✔/✔ (both options available)
Bore/Stroke 42/42 mm
Max. output (without generator) 7,2 HP (5,4 kW) @ 6700 RPM
Practical RPM range 1500 - 7000 min-1
RPM range 900 - 9500 min-1
Weight (without starter and pump) 1750 g
Spark plug NGK M10 (CM-6)
Fuel Unleaded 95-octane fuel
Lubrication Oil (Mobil Racing 2T) with petrol in mixture 1:40
Recommended propeller Mejzlik 24"x10" and 26"x10"
Recommended headers 1x 3413P
Recommended exhausts 1x 3511
Fuel supply 1x carburettor (Walbro HDA 189C) EFI system
Weight of fuel supply 1x 115 g 400 g
Ignition 1x ICU-S 1x ICU-PI
Weight of ignition 1x 185 g 1x 190 g
Fuel consumption @ 4200 RPM 1,8 l/hour 1,2 l/hour
Fuel consumption @ 5600 RPM 2,2 l/hour 1,5 l/hour
Fuel consumption @ 6200 RPM 2,4 l/hour 2,3 l/hour
Operating enviromental limits 3000 m 5000 m
Endurance time Approx. 300 hours (every 100 hours check) Approx. 360 hours (every 80 hours check)
Startability  X
System programming  X
Engine control  X
Installation ease  X
Electric starter with controller
Ignition 1x ICU-PS 1x ICU-PSI
Weight of starter (and controller) 600 g 600 g
Static thrust @ RPM 14 kg @ 6700 min-1 14 kg @ 6700 min-1