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Author Topic: my henry abe pistons and cyls compression Q  (Read 5085 times)

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Offline PeWe

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Re: my henry abe pistons and cyls compression Q
« Reply #25 on: October 21, 2015, 02:57:40 am »
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CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: my henry abe pistons and cyls compression Q
« Reply #26 on: October 21, 2015, 09:26:25 am »
Yes, that's it.

Don't have the dome height numbers. 
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As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline PeWe

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Re: my henry abe pistons and cyls compression Q
« Reply #27 on: October 21, 2015, 10:13:36 am »
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CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline BPellerine

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Re: my henry abe pistons and cyls compression Q
« Reply #28 on: October 21, 2015, 01:39:17 pm »
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Offline BPellerine

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Re: my henry abe pistons and cyls compression Q
« Reply #29 on: October 21, 2015, 01:49:08 pm »
so no one has any idea what compression ratio the ha stuff is,instructions say they increase comp so got to rejet?bill
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1978 CB 750K ard and webers
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Offline turboguzzi

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Re: my henry abe pistons and cyls compression Q
« Reply #30 on: October 21, 2015, 03:03:37 pm »
Quote from: BPellerine on October 21, 2015, 01:49:08 pm
so no one has any idea what compression ratio the ha stuff is,instructions say they increase comp so got to rejet?bill
just higher compression per se doesnt change flow characteristics, at least not much, shouldn't impact jetting (if it was good to begin with).
Did just a decking job on my xt600 supermoto, i.e. only compression was increased and at least in my case didnt need to touch jetting.
but if you are increasing displacement, not just compression, then flow speed through carbs will increase and jetting might have to change.

crazy price BTW, way out of my range....
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Offline BPellerine

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Re: my henry abe pistons and cyls compression Q
« Reply #31 on: October 21, 2015, 05:24:21 pm »
thanks turboguzzi,I am going from 61mm bore to 67mm bore with the stock combustion chambers,my pistons are flat top,so was just trying to get an idea of the compression increase,ie bigger bore into small combustion chamber,stock comp is 9.1 or thereabouts.bill
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Offline NalleyRacing

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Re: my henry abe pistons and cyls compression Q
« Reply #32 on: October 24, 2015, 06:33:53 pm »
 ;D

So I have a NOS HA kit I plan to install over the winter. I also am removing a old set of HA pistons from a motor currently. These are the old and new for you to compare side by side. Definately interesting. Im going back In to check weight and size differences.

The flat style are stock compression the newer styler are 10.25:1

New kit appears to be lighter. With deep fly cuts.
« Last Edit: October 24, 2015, 06:42:49 pm by TreyAllen »
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Offline scottly

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Re: my henry abe pistons and cyls compression Q
« Reply #33 on: October 24, 2015, 08:02:37 pm »
Trey, slide a piston pin halfway through each piston to compare the compression heights.
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Offline BPellerine

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Re: my henry abe pistons and cyls compression Q
« Reply #34 on: October 25, 2015, 04:35:00 pm »
yes trey that would be interesting to check height from pin,and yes your nos pistons are higher comp than mine,I was just trying to get an idea of what rise if any I would get/not get with the flat tops with std chambers ie bigger bore moving more air into them,it will not be much.bill
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another anfob

Offline PeWe

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Re: my henry abe pistons and cyls compression Q
« Reply #35 on: October 27, 2015, 02:55:50 pm »
Diameter of the older one?
Same as Bills or like mine that seems to be 0.5mm wider. 66.9mm at top, 67.45 around the skirt
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CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline BPellerine

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Re: my henry abe pistons and cyls compression Q
« Reply #36 on: December 06, 2015, 01:34:48 pm »
here are my pistons installed!lightly ported ko head going on top!bill
« Last Edit: December 06, 2015, 01:40:22 pm by BPellerine »
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1978 CB 750K ard and webers
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: my henry abe pistons and cyls compression Q
« Reply #37 on: December 06, 2015, 04:56:39 pm »
Looks great Bill. It's downhill from here.
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As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline BPellerine

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Re: my henry abe pistons and cyls compression Q
« Reply #38 on: December 07, 2015, 01:32:23 pm »
Quote from: Jerry Rxman Griffin aka MuthaF'er on December 06, 2015, 04:56:39 pm
Looks great Bill. It's downhill from here.
ya jerry that is what I am thinking too,always worked with twins,putting the barrels on a four is a whole ah hem,other experience !!done by spring!billp
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1978 CB 750K ard and webers
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