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Glowing header pipe

4 posts in this topic

Took my new 06 YZ450 up and down the street today for a little break-in ride and noticed that the header was glowing red. My 400 only did that when the timing was off due to a worn out cam chain. Is this normal, a result of the lean stock jetting, or ?

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If you haven't fooled with the jetting yet, I'd say you're still pretty lean.

Some glowing is normal if you let the bike idle too long. But if you're glowing red while you're riding it you are either too lean or have an air leak somewhere.

And yes, this is the most commonly asked question on the forum. However, I think it's dismissed much too routinely as completely normal where in fact there are several situations that exacerbate the condition. I installed my hot start wrong once and got the glowing red condition because I was way too lean. If I had asked here and gotten the instant 20 replies that it was completely normal I would still be rebuilding the engine.

There is a difference between the normal "idling too long glowing orange" condition and the "too lean glowing red" condition.

Stock jetting is way too lean and gave me a glowing red header too. Start with the fuel screw and go from there.

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