my brothers 2007 honda 400ex wouldnt start and we put the battery on the charger and when we did get it started the exhaust turned as red as an apple and we shut it off. Whats wrong, is a valve stuck or something

 

sounds like somethings wrong

 

Wouldn't start because of a dead battery, or some other reason????

Cold air is more dense, so it might be slightly lean which can make it hot. Don't let it just sit around idling...ride it or shut it off.

 

How long was it idleing? Usually a red hot head pipe is a sure sign of lean, or idleing way too long.
Is the motor totally stock....lid is installed on the air box?

 

The 400 has a single wall pipe. If you hold the throttle open with no load for a spell, it will turn red. If it is doing it idling, I would look into the pilot jet being restricted making it lean and start hard

----- Gregg -----

 

you could check your valves make sure you mave proper valve adj. it should be .006 on the exaust side and .005 on the intake the book calls for .005 and .004 but the .006 and .005 seem to work a little better