I have a 1998 KX 250. I've owned and rode the bike regularly for over 6 months and it's ran great. Recently it's started surging on deceleration when it as operating temperature. It continues to runs great until it warms up. I have done nothing different with fuel or mixture. have a clean air filter and a new plug. It feels like an ignition problem to me, but could be carburation also. I've had the carb set to factory settings and it runs super until it gets warm and I'm coming down from a long to medium acceleration. It has a fuel solenoid in the carb, but I'm not sure if this could cause the problem. I can't afford to fix by guess, would appreciate any assistance in troubleshooting this problem.