on the it175 the suspension is it's biggest weak point. swap in a set of yz forks/triples and check spring rate - all it175's are spring too soft unless you weigh 145lbs - and original springs are pretty beat up after 30 years..... change rear spring for a stiffer one. rebuild rear shock while you're at it (i can't remember if it175 81 is rebuildable, the earliest ones were not. but i assume it is). also check specs on the fork tube height in the triple trees - many set them back to even with the top, when they really should be at 50mm sticking out top (might be different for 1981 - i only know the j/k models)) the motor is what it is, runs good mid/top, not bad low grunt, but nothing like the it200, so maybe figure a flywheel weight, or work on squish/porting. the it175 motor shifts better than the it200, i'll give it that for sure.
07 gasgas xc300-94 duc 900ss-86 morini camel (2)-84 IT200-83 IT175-78 guzzi lm1-77 pursang 250-76 morini 3 1/2 strada-76 frankentaco pursang 200-74 frankentaco pursang 200-74 morini 3 1/2 sport-74 mz ts250/0-74 puch 175 (3)-73 can-am 175tnt-71 guzzi frankeneldo-71 ossa Stiletto-70 frankentaco sherpa s(2)-66 morini corsarino(2)-63 morini corsaro + many more