I am looking at a 1980 Suzuki GS550L. The bike only has 5700 miles on it and the plugs, plug wires, carborator diaphiams and battery have all be replaced and the bike will not turn over. The bike has been sitting for some time. The only way it will turn over it you run the starter for a long time and have the throttle at full and once started, if the bike is turned off, it will not start up right away. Does anyone have an idea on what the problem could be?? I am new to motorcycles and looking for some help.