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Ok, I idolize, worship the new 2018 YZ450F (new for me because I bought it late in the year). Haven't had any starting issues or had to use the new starter plunger until the winter temperatures crept in. I keep it in an off and on heated garage, but in the morning it's cold, and would not start so easily anymore as it did in the summer, where I never before had to use the starter circuit. The F.S.M says to push the plunger all the way in, then hit the starter, and let the engine run/rev at 3000-5000rpm!!! for 1-2 minutes. Then, your supposed to operate the throttle, as the chop throttle direction is supposed to kick the plunger back out to its N.O.T. position. I did exactly this, but, when I operate the throttle, the throttle close direction DOESN'T kick the plunger back out. The engine was revving at about 3100rpm for only about 40 seconds, when, to my dismay, I looked down at the engine & exhaust pipe; the exhaust pipe exiting the cylinder port was glowing so hot I swear it was almost molten! Screaming inside my head, I quickly grabbed a pair of long slip joint pliers to pull the plunger back out (or else I'd no doubt brand myself on the glowing exhaust), and the motor rpm dropped to a more conventional warm/idle up speed. I then had to accelerate the water pump briefly, then cut the engine. I waited a few seconds, and started it up again, and varied the throttle slightly. I repeated this a few times in order to cycle the motor, and safely remove the heat conduction thru the cylinder head. My YZ450F runs great, post incident, and has more power than ever now. My only issue is now I have to always have a pair of pliers when cold starting the powerhouse, because the throttle and starter plunger still don't communicate. I DON'T let it run for more than like 15 seconds on fast idle anymore. My question is, WHY did the pipe heat up so much if that is how long it's recommended to fast idle, AND does anyone else have this issue with their starter plunger sticking, or had their pipe heat up orange hot? I went to the dealership to correspond with the mechanics there and no one was able to give me any information. Please, ONLY 2018+ YZ450F owners need reply on this thread, as it is a BRAND NEW starting device on a fuel injected engine for Yamaha, so other instances or experiences will not apply.