The high-tech GF four-valve mill scooped out to 165cee-cees.

The GF170 retains the basic architecture of the GF125 powerplant but with a number of refinements and revisions to boost power and iron out vibrations. Compared to the GF125, the mill is now bored out to 60mm (from 57mm) and stroked to 58.4mm (from 48.8mm), resulting in a volumetric displacement of 165.12cc while the head incorporates four valves, only the third bike (after the BMW F650 and GF125) in the country to do so. Breathing is via a UCAL Mikuni CV carburettor (29mm choke) with a coaster rich circuit for adequate idling Performance. The GF125 did without the CV carb in spite of the original Hyosung bikes having one that hampered the efficiency of the motor. Thankfully this has been rectified in the 170.

The mill now develops 14.6bhp at 8000rpm while max torque of 14.2Nm is developed at 6000rpm (though the torque curves we were supplied with indicated the max torque at 7000rpm). Considering the engine redline at 9000rpm, both the power and torque are developed quite high in the rev range, a characteristic of four-valve engines which becomes quite evident On the Road though more of that later. Compression ratio has been lowered to 9.3 from 9.92, possibly keeping Indian fuel quality in mind. Digital ignition takes care of timing the spark for better combustion efficiency.

The R&D department has also worked extensively on refining the powerplant. The twin-chambered air filter has an optimised air flow rate and increased volumetric efficiency, the piston crown has been modified for better squish and to minimise wear rate, the cylinder block has additional fins for better cooling, the combustion chamber has been optimisd for better efficiency and the oil pump (gear type) has been upgraded for increased oil delivery. A counterbalancer mounted on the crank attempts to iron out most of the engine vibrations, while the engine is rubber mounted to the frame to iron out rouge vibes.

The five-speed ’box has been carried over from the GF125 and sports identical ratios, with only the final drive ratio altered to take into account the increased horsepower. The repositioning of the footpegs has eliminated the cumbersome gearshift linkage and in so doing solved all the gearshift problems of the GF. To be honest, this ’box rates as one of the finest units in the country, power shifting up the ratios and blipping down being an absolute joy (never necessitated use of the clutch either way) and never once did she find a false neutral. Finding true neutral was never a problem though like I said earlier the gear indicator display gets washed out under the glare of the sun and the absence of a neutral indicator makes this problematic. The one-way clutch has been beefed up with additional plates to withstand the higher load. Honest, this is one of the most progressive and seamless clutches I have come across.