Author Topic: pistons cb 750A from 61mm to 65mm.  (Read 1047 times)

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Offline ORAZIO

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pistons cb 750A from 61mm to 65mm.
« on: January 23, 2020, 08:15:27 am »
I have read your discussion where some have transformed the sohc from 736cc to 836cc.
I want to do it, but I measured the cylinder shirt which is only 68mm.
only 1.5mm of metallic thickness remain. Are 1.5mm sufficient to withstand the increase in performance of this engine?
help me find this discussion post.
Thank you
Orazio

Offline raymond10078

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Re: pistons cb 750A from 61mm to 65mm.
« Reply #1 on: January 24, 2020, 11:35:42 am »
First, this is the perfect example of a question best suited for a different Tech Forum - as the question is not limited to the "A" model.

Regardless, as this is a common practice, if it had resulted in horrible consequences, we'd all know, or we'd have heard about it.  The 836 kits just required boring.  Sleeves do not require replacement.  Call the various vendors if you like to validate.

In the interim, here are some search results that seemed applicable:

http://forums.sohc4.net/index.php/topic,22721.msg234051/topicseen.html#msg234051

http://forums.sohc4.net/index.php/topic,171550.msg2014461.html#msg2014461

These one says that 850cc is ok without replacing sleeves:

http://forums.sohc4.net/index.php/topic,58101.msg667135.html#msg667135

http://forums.sohc4.net/index.php/topic,99832.msg1114885.html#msg1114885
1978 CB750A (upgrading very, very slowly)

Past bikes - Honda: SL350, CX650C, CB900C, CB1000C, CM450A; Kawasaki: several 1972 750 H2's; Suzuki: TC90J.

Bikes I want: CX650ED, a mid-sized japanese V-twin with ABS.

Offline ORAZIO

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Re: pistons cb 750A from 61mm to 65mm.
« Reply #2 on: January 24, 2020, 01:14:52 pm »

Hello raymond10078
thanks for pointing out the links that deal with the topic.
I will have to read a lot but already the first answer is a reassuring confirmation for a successful 836 cc conversion of the engine
Thanks Horace