head milling calculator
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Tourer
Joined: Jun 2016
Posts: 396
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From: Maple Ridge BC & Chiangmai
head milling calculator
103" Twin Cam heads with ACR
I am familiar with the Big Boyz head porting calculator and how to calculate combustion chamber size to achieve the desired static compression ratio
Is there a calculator for how much to mill the head for a Xcc reduction in chamber size?
These are spare heads and the ACR's are out.
Does installing the ACR change the combustion chamber volume and how to measure volume with this hole in the chamber?
I am familiar with the Big Boyz head porting calculator and how to calculate combustion chamber size to achieve the desired static compression ratio
Is there a calculator for how much to mill the head for a Xcc reduction in chamber size?
These are spare heads and the ACR's are out.
Does installing the ACR change the combustion chamber volume and how to measure volume with this hole in the chamber?
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Joined: Dec 2005
Posts: 19,922
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From: poway
The rule of thumb on a standard combustion chamber shape for twincams is 0.007" of milling removes 1 cc from the chamber.
You need to plug the hole.. Modeling clay work. 12 x 1.25 mm bolt and some grease.. Anything.. Only need to hold liquid long enough to make the measurement..
You need to plug the hole.. Modeling clay work. 12 x 1.25 mm bolt and some grease.. Anything.. Only need to hold liquid long enough to make the measurement..
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Tourer
Joined: Jun 2016
Posts: 396
Likes: 20
From: Maple Ridge BC & Chiangmai
My other bike has Husquavarna pop up type manual compression releases, and I have never seen a head with ACR's, so unaware if the ACR when installed changes the volume
Will simple plug the hole flush then
HDF Community Team
Joined: Jun 2006
Posts: 12,776
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From: san antonio
Which is why I asked as it is not a simple formula as the chamber and volume shape will change as one cuts.
My other bike has Husquavarna pop up type manual compression releases, and I have never seen a head with ACR's, so unaware if the ACR when installed changes the volume
Will simple plug the hole flush then
My other bike has Husquavarna pop up type manual compression releases, and I have never seen a head with ACR's, so unaware if the ACR when installed changes the volume
Will simple plug the hole flush then
BTW, I have only seen a couple off sets of the ACR heads and the ones I saw, the ACR finished very near flush with the chamber surface and so do the plugs HD sells to plug those holes.
Last edited by djl; Jun 5, 2017 at 12:48 PM.
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