Bringing the OS petrol engine technology into the smaller class of model, the OS GT-22 has all the sophistication that you would expect from OS in terms of quality of manufacturer and innovative design yet manages to combine it all in a compact, powerful package.
Like the GT-33, the GT-22 has a steel liner for durability, a lightweight, ringed piston and a one piece crankcase. OS are the masters of optimising internal designs in a way that allows superb performance combined with easy starting, long life. The design is from the ground up rather than adapting old technology for a different use. Deep fins are needed to carry away the extra heat generated by petrol engines and OS use their casting expertise to make them efficiently thin to be able to do that.
Inside, OS have craftily used a special design of aluminium conrod with pre-installed roller bearings. Using aluminium instead of steel like many of the strimmer based engines means reduced reciprocating mass. This in turn means reduced crankshaft counter-balance. Not only does it reduce weight overall, it also allows quicker throttle response, higher RPM and reduced vibration. Years of experience in actual engine design means that OS find innovative solutions to many problems.
Carburation come courtesy of a real 'Walbro' carburettor adapted by OS for the GT-22. Being a 'pumped' style of carburettor, tank height/location is a little less critical than a non-pumped carburettor. Once set for the fuel being used, it requires almost no adjustment.
Ignition is provided by a sophisticated unit that is also common to the GT-33. The main HT lead is shielded to prevent spurious emissions and the spark is delivered by a high quality CM-6 spark plug. Not quite a fit and forget system but pretty close!!
OS engines are never the cheapest, but like all things in life, you get what you pay for and every OS is guaranteed to have the very best quality, time after time.