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Header glowing cherry red??

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I just picked up a 05 YZ250F. Bike was running pretty lean so I decided to check the valves. As I got into it a little bit, I decided just to check the whole motor. Scraped the carbon from the piston and head, checked the valve seats, etc. etc...Cleaned the carb. Checked the valves. Outside 2 of the 3 valves are tight. Put everything back together. Started the bike. Took a cruise down the street to get the mail and noticed my pipe is glowing cherry red. I mean pretty bad imo. I could easily light a cigarette off of it. The first 3-4 inches are like this. I can't see this being normal. I'm open to any and all suggestion and theories. I am a rookie with a 4 stroke motor. My wrench history is all on 2 strokes and I don't even know where to start to diagnose.I'm new to this forum and would like to thank everyone in advance for any help and to all those who welcomed me already.

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is normal, the header being red. dont use it for a cig lighter though, ride it like ya stole it.

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It's normal if you're idling at a stand still not while riding. If you're riding and it's like that then you are probably too lean

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I'd be far more concerned with the tight valves than a glowing header. Tight valves mean the seats and valve heads are wearing, probably from poor air filter maintenance, or else the valve heads have distorted from constant banging off the rev limiter.

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I meant the clearance was a little on the tighter side. As far as up and down, they flow smooth. I checked the valve heads and seats. They must be newer. They were to close to factory specs for a 7 yr/old bike. Thx though, I'll know to keep and eye out for that chokey.

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