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Author Topic: 67.5 mm =cc??  (Read 5094 times)

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Offline lash

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Re: 67.5 mm =cc??
« Reply #25 on: November 27, 2019, 10:06:47 PM »
It will be a while before I can measure the case... :-\
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Offline BPellerine

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Re: 67.5 mm =cc??
« Reply #26 on: November 28, 2019, 08:29:18 AM »
Quote from: Terry in Australia on November 27, 2019, 06:54:06 PM
Quote from: lash on November 27, 2019, 05:56:43 PM
Not sure what you mean about bigger base gasket and grind away?

The "Blue Ridge Mountain engineer" method of boring each cylinder hole in your top case is to put the oversize base gasket in place, mark the cases tracing the bigger holes, remove the gasket and get stuck into it with a die grinder or dremel tool, File, Bowie Knife,  or whatever cutting instrument you have available, usually conducted while drinking moonshine and wearing Dickies overalls and a straw hat. ;D
haha,just one way of doing it if you dont have access to a good machine shop,could be tapered sleeves,cyclex?made pistons to clean up a 67mm bore,with 67.5,I think they also made tapered sleeves,as did henry abe which I have.bill
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Offline 754

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Re: 67.5 mm =cc??
« Reply #27 on: November 28, 2019, 10:13:38 AM »
You mean stepped sleeves.
 I got to ask the OP, when you measure the pistons, has to be at the skirts, 90 degrees to write pin... not sure where you measured.
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Online PeWe

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Re: 67.5 mm =cc??
« Reply #28 on: November 28, 2019, 12:07:24 PM »
CyckeX still sell that kit with 67.5mm Wiseco pistons and sleeves. CR 10.25:1They call it "915cc" which is not correct, diam is.

They sell 890cc too. CR 12.5:1
« Last Edit: November 28, 2019, 08:43:54 PM by PeWe »
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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 lash

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Re: 67.5 mm =cc??
« Reply #29 on: November 28, 2019, 01:42:25 PM »
more pics. The case is from an old 71 stock engine and the cylinders fit with no grinding.
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Offline lash

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Re: 67.5 mm =cc??
« Reply #30 on: November 28, 2019, 01:45:14 PM »
more...
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Offline BPellerine

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Re: 67.5 mm =cc??
« Reply #31 on: November 28, 2019, 02:01:40 PM »
then they are stepped sleeves as Frank said,I think 67.5 is the limit for those sleeves so they are a one shot deal,no more overbore.bill
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Offline 754

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Re: 67.5 mm =cc??
« Reply #32 on: November 28, 2019, 03:24:21 PM »
 Looks a lot like a 77 or 78 F head. Look on the top back of head for number between 2 and 3 cylinder, it should say 410 or another number.
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Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Online PeWe

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Re: 67.5 mm =cc??
« Reply #33 on: November 28, 2019, 08:46:00 PM »
Head ported too?
« Last Edit: November 28, 2019, 08:52:06 PM by PeWe »
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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 lash

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Re: 67.5 mm =cc??
« Reply #34 on: November 29, 2019, 06:39:12 AM »
Says 410. Dont know what a ported head looks like but this is no.2 intake..
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Offline Old Scrambler

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Re: 67.5 mm =cc??
« Reply #35 on: November 29, 2019, 07:12:36 AM »
Looks like it was 'cleaned-up' but not really ported..........Is there any machining to the chamber?
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 67.5 mm =cc??
« Reply #36 on: November 29, 2019, 07:57:08 AM »
Good start on a HP engine. Big pistons and big valves. Big cam?
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Offline lash

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Re: 67.5 mm =cc??
« Reply #37 on: November 29, 2019, 08:22:18 AM »
I never got the valves or a cam with it. I’m not really interested in building a big power engine, these just came with the package.
My stock bikes are fast enough!
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Offline Terry in Australia

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Re: 67.5 mm =cc??
« Reply #38 on: November 29, 2019, 02:31:40 PM »
Yeah, the F2 head is no real performance improvement really as the negatives outweigh the positives. ;D
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