I've got a 1980 Suzuki GS250 that is giving me problems when starting. When I try to start it, the starter will turn a bit, but slowly, then stop. The battery is fully charged, and when I press the starter switch the voltage drops to about 8 volts. I just replaced the battery, and gave it a full charge. I also pulled the starter and tested it outside the bike via a jump box. Wires tested good as well. Does this bike have any common problems or can anyone recommend a next step?