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sk8bd117

08 yz450 rust coloring on intake.

6 posts in this topic

I noticed today a rust or copper colored mark in my intake today. When I rub it with my finger it doesn't come off. Could this be from something like overheating?ImageUploadedByThumper Talk1393693264.489546.jpgImageUploadedByThumper Talk1393693276.324956.jpg

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That has got to be fuel deposits or deposits from combustion. It's definitely not rust on a aluminum head. Is there any signs of this in the carb, intake boot or air filter?

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That has got to be fuel deposits or deposits from combustion. It's definitely not rust on a aluminum head. Is there any signs of this in the carb, intake boot or air filter?

No,

There is no other sign if It on the intake side at all. But the divots for the exhaust valve on the piston had slightly the same coloring. The motor was slightly out if timing. About one tooth advanced on the exhaust side. Bought the bike used and don't know the past ImageUploadedByThumper Talk1393901790.409938.jpg. Notice there exhaust can(left) is advance about one tooth when at top dead center

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As pictured, both cams are about a tooth advanced, and they are both the correct distance from one another (13 pins), which means nothing, timing-wise, but it makes it very unlikely that the engine jumped time by itself.  It either wasn't at TDC when it was timed, or it wasn't when that picture was taken, one of the two.

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