Header pipes glowing red

SOURCE: 2006 yz250f header is glowing at idle, has not done this before.

combustion chamber is tooooo hot.  Mixture is way to lean

SOURCE: glowing exhaust header yamaha wr250f

It won't be valve timing or clearance. The fuel/air mix would be the culprit. Clean the carburetor with special attention to the idle circuit. Remount the carb with new manifold gaskets. A manifold air leak will mess up the mixture. Also, get a new spark plug one heat range colder than stock. Hope this helps out!

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SOURCE: i have a 2001 yamaha wr250f and after running only

Air leak causing a lean fuel/air mixture, bad radiator cap killing pressure in the cooling system, low water in the radiator, plugged radiator, broken water pump, not using premium gas and a spark plug with the wrong heat range.

Please rate this solution. Thanks rodsixfifty! < cool name

SOURCE: Exhaust header pipes getting glowing red hot

the pilot jet is too only make the bike idle so it wouldnt be this is the engine have lots of oil in the engine

Testimonial: "I haven't thought of that but I will put a little more oil in it and try it again. Will let you know the results later. Thanks"

SOURCE: my crf250 wouldnt start so put new shims in so

Possible causes are:
Insufficient valve tappet clearance. Re-check the tappet clearance on each valve. You can confirm this by checking the compression. Proper compression for your engine is 175~190 psi. Much lower than that indicates insufficient tappet clearance - or internal engine wear.
Fuel mixture too lean. This can easily be caused by clogged carburetor jets, from sitting. It only takes a few months on non-use for the carb to become plugged with fuel varnish. Also make certain there are no air leaks between the carburetof and engine. If you are running an aftermarket air filter, rejetting to correct a lean mixture is required.
Whatever you do - do not operate the engine in this condition or you risk damage to the cylinder head and valves.