Is milling a head .005 inch allot?

casper
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casper
Edited Date/Time 2/20/2014 9:43am
I overheated my bike pretty bad and ended up warping the head. My friend that has a machine shop milled the head flat again and took off .005 of an inch. I'm not an engine builder so I was wondering if that's allot to take off or is somewhat normal when milling a head?
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slipdog
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slipdog 2/19/2014 6:09pm
2/19/2014 6:09pm Edited Date/Time 2/19/2014 6:15pm
Not much at all, a lot of bikes can safely go .015" or more. Depends on the bike though
casper
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casper 2/19/2014 7:50pm
2/19/2014 7:50pm
kx450. It's up for new valves and I was thinking of putting some money into the head, but was wondering if I should find one that hasn't been overheated.
bangmyhead
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bangmyhead 2/19/2014 8:02pm
2/19/2014 8:02pm
hey slip,
when you mill the head do you gotta run race gas?
slipdog
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slipdog 2/19/2014 8:30pm
2/19/2014 8:30pm
casper wrote:
kx450. It's up for new valves and I was thinking of putting some money into the head, but was wondering if I should find one that...
kx450. It's up for new valves and I was thinking of putting some money into the head, but was wondering if I should find one that hasn't been overheated.
First let me say I had 2 strokes on the brain, but I don't see .005" as a big deal at all. On a 4 stroke that will raise the compression a small amount but doesn't change the squish clearance. Your cam timing will be slightly different also, but again a small amount and wont really be noticeable. You "should" check your piston to valve clearances and degree in the cam, but at .005 I personally wouldn't worry about it.

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slipdog
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slipdog 2/19/2014 8:40pm
2/19/2014 8:40pm
bangmyhead wrote:
hey slip,
when you mill the head do you gotta run race gas?
Not necessarily, It depends on the motor, how much you mill off and what combustion pressure you have. I personally like to have good race gas in any motor once you start modifying it, but you don't always have to.
Paw Paw 271
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Paw Paw 271 2/20/2014 9:43am
2/20/2014 9:43am
.005" is almost nothing! I would not be concerned in any way about it. I suggest you will not see any ill effects nor need additional valve clearance issues nor the need for race gas.

Paw Paw

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