check compression(should be well over 100psi, the higher the better) check for broken engine case from chain breaking around front sprocket,check for side to side play in swing-arm. check for bent rear axel.(you can feel it on the test ride). look for coolant leaks around the head and cylinders. make sure carbs are cleaned and serviced before you ride if you buy the machine.if its in real good condition $2000 is a fair deal.