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Author Topic: Big Bore??  (Read 438 times)

Offline archie2133

  • Posts: 4
Big Bore??
« on: Nov 24, 2018, 10:18:36 »
Hi guys,

Im wondering if you can help me. Im doing a top engine rebuild on my 1975 Honda Cb750f and I'm changing my piston rings.

Upon pulling the pistons out I found that the bore measures 65mm and the pistons are stamped "STD" for what I assume is standard.

When consulting my work shop manual it states that the bore and rings should measure 61mm.

Im guessing these pistons aren't from the original engine abd that the head has been bored??

Should I just leave the pistons and buy 65mm rings to suit??

Thanks

Archie

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Offline irk miller

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Re: Big Bore??
« Reply #1 on: Nov 24, 2018, 10:36:43 »
65mm is an 836cc bore.  That's a great deal.  Keep it and get your 65mm rings, as long as your sleeves and such check out okay.

Offline cxman

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Re: Big Bore??
« Reply #2 on: Nov 24, 2018, 11:33:45 »
run a 180 0r 240 ball hone through the bores to deglaze if the bores are good and fit new rings
1978 CX650 Super Deluxe
1979 XS1100 Special
1974 xl350
1983 cx650 Custom
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1974 kawasaki 350 bighorn
1983 GL1100 aspy full dress
1983 GL1100 Nekid
and a bunch of others

Offline archie2133

  • Posts: 4
Re: Big Bore??
« Reply #3 on: Nov 25, 2018, 17:39:43 »
Thanks guys. I've got it honed and ready to go. Will I aso need a different type of head gasket if it has been bored??

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Offline irk miller

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Re: Big Bore??
« Reply #4 on: Nov 26, 2018, 00:24:39 »
Just a head gasket made for that bore.  It can be the same material as stock, MLS, or copper.