EVO All Evo Model Discussion

head volume

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Old Feb 16, 2015 | 06:29 AM
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Been all over the net, can't find the answer; what is the stock head volume? I measured mine and came up with 74.5 cc's
 
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Old Feb 16, 2015 | 06:39 AM
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Originally Posted by graultytc88
Been all over the net, can't find the answer; what is the stock head volume? I measured mine and came up with 74.5 cc's
Are you talking about EVO heads (this is the EVO section after all) or are you talking about the heads of your 96" motor that is in your signature?
 
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Old Feb 16, 2015 | 10:18 AM
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I have a 1995 80" evo. Came with a ev51 cam in it, no domed pistons, need to determine if the head is shaved.
 
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Old Feb 16, 2015 | 11:17 AM
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Originally Posted by graultytc88
Been all over the net, can't find the answer; what is the stock head volume? I measured mine and came up with 74.5 cc's
I was wondering how you measured it.
 
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Old Feb 16, 2015 | 12:48 PM
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Piece of plexiglass with hole in it, stuck down to leveled head with thin bead of grease. Fill chamber with syringe.
 
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Old Feb 16, 2015 | 06:35 PM
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I think around 82cc . Sounds like yours have been cut. You can also measure from the head gasket surface to the top of the rocker cover gasket surface & uncut height should be around 3.740, give or take a few thousands.

Ride Safe,
Harold
 
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Old Feb 16, 2015 | 07:25 PM
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Originally Posted by LowriderHarold
I think around 82cc . Sounds like yours have been cut. You can also measure from the head gasket surface to the top of the rocker cover gasket surface & uncut height should be around 3.740, give or take a few thousands.

Ride Safe,
Harold
Thanks, for the info and the suggestion to measure the head, hadn't even considered doing that.
 
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Old Feb 16, 2015 | 08:20 PM
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Originally Posted by LowriderHarold
I think around 82cc . Sounds like yours have been cut. You can also measure from the head gasket surface to the top of the rocker cover gasket surface & uncut height should be around 3.740, give or take a few thousands.

Ride Safe,
Harold
Just measured the head at 3.656" so if your number is near correct than the head is shaved down around .080" and according to this chart,
http://www.nightrider.com/biketech/h...ompression.htm
I have around 9.73:1 compression; good for the ev51
This also confirms my volume measurement when put in the Big Boyz compression calculator, which was producing less compression, 9.34:1
Not sure which one is more accurate, but the bottom line is that at least whoever did the work didn't just put the wrong cam in it.
Thanks again for the info.
 
Attached Thumbnails head volume-_57ab.jpg  
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Old Feb 16, 2015 | 08:27 PM
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stock is suppose to be 83cc but it can be anywhere from 81cc to 85cc. if yours are 74 they have been cut thats the volume that most hot rod builders shoot for. with 74cc heads .030 head gasket wiseco 10:1 pistons .003 in the hole and a wood w-9 cam will give you 11:1 static compression and 9.67:1 corrected that's as high as you can go on pump gas.


with flat top pistons and ev51 cam your static would be 9.3:1 and corrected is 8.4:1
 
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Old Feb 16, 2015 | 08:35 PM
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Originally Posted by graultytc88
Just measured the head at 3.656" so if your number is near correct than the head is shaved down around .080" and according to this chart,
http://www.nightrider.com/biketech/h...ompression.htm
I have around 9.73:1 compression; good for the ev51
This also confirms my volume measurement when put in the Big Boyz compression calculator, which was producing less compression, 9.34:1
Not sure which one is more accurate, but the bottom line is that at least whoever did the work didn't just put the wrong cam in it.
Thanks again for the info.

don't use that chart its wrong you never just mill so many thousandths off a head always cc them.
 
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