If it has floorboards and heel/toe shifter(and sometimes the stock shifter too) , be forwarned, the pre 97 transmissions are subject to loosing 4th gear if the PO left their foot on the shifter between shifts which bends the weak fork and wears the 4th gear. It will sound like a box of rocks in 1,2&3rd gears to start then 4th will start popping out of gear. You can ride it skipping 4th into 5th for some time without any more damage. The repair requires splitting the cases or getting a replacement 97-2000 motor.
Get the front wheel 4 to six inches lower than the rear and listen for any clicking sound. Then turn the bike around, so the rear wheel is higher and listen again. I don't remember for sure, but one way will make the clicking sound and the other way the sound goes away.
Doesn't seem to matter whether the bike is in gear or not, as long as it isn't in 4th or 5th.
If you get a clicking sound, the fourth gear shifter is bad!