Yesterday, I was working my 394XP pretty hard. We were firewooding a 52" Willow Oak, cutting off 16" slabs, then ripping them small enough to handle getting to the splitter. I was running tank after tank of gas through it. After about 4 1/2 hours, the brake handle got so hot that the rubber / plastic slumped down and warped. Also, the plug wire, which runs adjacent to the cooling fins on the cylinder, melted through ands shorted out. We plan to check the piston, rings and cylinder for damaged since it got that hot. What would cause such a spike in temperature so quickly after running perfectly all morning? We want to avoid this happening again.