Have you been performing any "adjustments" to the carburetor? YES / NO
It has coolant and the fan kicks in? YES / NO
A '98 with 4800 miles on it has sat far more than ran. My suspicions lean towards a carburetor with a gradual varnish build up, creating a lean running engine. This can be confirmed or dismissed by pulling the spark plug and reporting the prominent color of the spark plug electrode. A lean carburetor will create more heat faster than running the bike without coolant. Is the bike entirely stock, or has it been modified?
EDIT: If you can, run the engine until the fan kicks on again, and confirm that the fan blade is spinning. They do have a tendency to quit doing that. 'Specially after they go "tim-ber".
Last edited by vatrader; 05-06-2010 at 06:47 PM.
Reason: Added content