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broncomoto

Galactic Foul-up - YZ450f Head decarbonize

12 posts in this topic

While decarbonizing my head I decided it was time to speed up the process with my dremmel tool. once I sprayed the loosened carbon off, I realized that even though I used the wire wheell, I removed the top 25% of the coating from the intake barrels. Am I toast? What is the best way to remove 200 hours worth of carbon from the head and the valvues? Bronco, Austin, TX.

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I removed the top 25% of the coating from the intake barrels.
Explain this. Are you speaking of ports or valves? Were the valves assembled in the head or loose?

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i removed the valves and proceeded to decarbomize the exhast port barreles. i inadvertantly ran the dremmel whell into the intake port barrels. before I knew it, i removed the top portion (about a 1/4 inch from the top of the head) of the coating. if you account for the distance between the carberator intake and the valve seat, about 1/8 of the coating is gone and thats all at the top near the valve seat. im hopeful that the fuel would well be atomized by the time it reaches that point, but dont want and fuel puddling to become a performance issue. cant email pictures wiythout too much difficulty. Gray, youe usual advice would be greatly appreciated.

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i removed the valves and proceeded to decarbomize the exhast port barreles. i inadvertantly ran the dremmel whell into the intake port barrels. before I knew it, i removed the top portion (about a 1/4 inch from the top of the head) of the coating. if you account for the distance between the carberator intake and the valve seat, about 1/8 of the coating is gone and thats all at the top near the valve seat.

"Barrels" is not the correct term for the ports in the head where the valve seats are located and through which the intake air and exhaust gases flow. Those are "ports".

There is no coating of any kind in the ports or on the valve seats, so I don't know what you thought you did, but you did not remove any coating from there.

The valves are coated with a titanium nitride compound but only on the face that contacts the valve seat. Avoid contacting that face with a wire brush and you should be OK. As a practical matter, you might possibly damage the valve face with a wire brush, but you'd be more likely to add a coating of steel than to remove the Ti Nitride. Nevertheless, stay off the valve faces and seats where you can, and be sure you get the valve back in their original locations if you aren't replacing them.

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the intake ports are rough not polished. I understand this is necessary for the gas to turn into vapor before detonation. what I did was near top of the port up near the valve seat, I smoothed this out about 15% of the way down. I understand that its OK for the exhaust ports to be polished, but one does not want the intake posts to be polished, they should be rough. just wanted to know if this is going to diminish performance.

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I assume you were using a wire wheel on your dremel? I don't see how you could "polish" the ports enough with a wire wheel to be an issue. Also, you may have your terminology confused. The valve seat is at the bottom of the port. The valve guide is at the top.

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the intake ports are rough not polished. I understand this is necessary for the gas to turn into vapor before detonation. what I did was near top of the port up near the valve seat, I smoothed this out about 15% of the way down. I understand that its OK for the exhaust ports to be polished, but one does not want the intake posts to be polished, they should be rough. just wanted to know if this is going to diminish performance.
The intakes in a high performance application should be a smooth, sanded finish, but not mirror polished so as to encourage the presence of a boundary layer of air. That layer "sticks" to the port wall and becomes a sort of bearing for the fuel droplets so that they remain in the air flowing through the port, rather than flowing along the port wall as liquid. The fuel atomization itself is done by the carburetor/injector, not the port.

As was said, you could not have done any seriously significant polishing with a wire brush, anyway, so who have nothing to worry about.

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