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Author Topic: measureing bore and pistons  (Read 3401 times)

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Offline cadler

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measureing bore and pistons
« on: April 05, 2005, 03:30:34 AM »
I bought a set of pistons with rings with a cylinder head for a K1 cb750 that were used but from thec same engine
I need to know if the rings will be ok or will I have to buy A new set.
i need to measure the bore and then the rings. Does anybody know how the tolerances to determin if I need to get a set of rings?
Thanks
Craig
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Offline MRieck

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Re: measureing bore and pistons
« Reply #1 on: April 05, 2005, 04:51:51 AM »
 Replace the rings. You need a bore gauge to measure the hole and  2" to 3" micrometer to measure the skirts- subtract the skirt diameter from the hole diameter and that's clearence. You'd be better off taking the cylinder and pistons to a machine shop and having them do it. If there are in spec have them deglaze the cylinders and use the new rings.
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Offline Terry in Australia

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Re: measureing bore and pistons
« Reply #2 on: April 05, 2005, 05:00:22 AM »
If you can't get your hands on a good micrometer buy a cheap new digital vernier caliper, mine cost $17.00 on ebay, and is more accurate than my quality japanese NSK and Mitutoyo devices. You can also buy expanding bore gauges on ebay for a few bucks. Cheers, Terry. 8)
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Offline cadler

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Re: measureing bore and pistons
« Reply #3 on: April 05, 2005, 05:49:29 AM »
Thanks
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MotoDave

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Re: measureing bore and pistons
« Reply #4 on: April 07, 2005, 08:51:24 AM »
Agreed.  Even if the piston to cylinder clearance is good you still need to rehone.  However, rehoning with those auto part store/ craftsman hones is not really good enough.  It's well worth the money to have them straight honed by a machine shop.  They will only take a few tenths off at most and will ensure the cylinder is straight and round.  Should cost about $15-$20 a cylinder.  Plus, a shop can bead blast the old pistons to clean them and actually "grow" the diameter a half a thou to make up for any lost clearance in honing.  This was the route I was going to take....before I threw down for an 836 kit  ;D
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