just cleaned the carb on my 03 yz450f and changed out the plug. kicked it over and the pipe stated glowing coming out the head. there was coolant in the radiator so what would cause it to heat up that fast and that hot?

Bike is running lean. Check the setting on your air screw.

Bike is running rich, check your fuel screw.

On a YZF450 it is normal for the head pipe to glow after a few minutes of sitting without air flow through the radiators. If the pipe starts to glow after only a few seconds, you may have leaky exhaust valves.

i will mess with the fuel see what happens

The bike is air cooled. dont let it idle for more than a minute on the stand.

it was within seconds it started doing it. hopefully it is something simple.

Bet you the choke makes it worse/brighter?

Good one Bob! How many bikes you ever melted down running too rich?

Assuming, as Ol89r correctly pointed out that the exhaust valves are sealing properly a higher than normal exhaust gas temperature is the result of delayed combustion which dumps additional heat into the exhaust system. The most common causes of delayed combustion?

- retarded ignition timing
- too lean a mixture
- too rich a mixture

plynn - If you are going to mock somebody you might want to do some homework so the correct person looks like an ass.