Piston bore clearance

Top End (cylinders pushrods etc.)
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Weston1955
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Piston bore clearance

#1

Post by Weston1955 »

Going to bore my cylinders .010 over and had a question about piston clearance specs. I received my new superior pistons today in the mail and there is no spec sheet with them. Anyone have a recommendation on the clearance for these type of cast pistons? I've read both .0015 and .0025 so I thought I'd ask the forum to get a definitive answer. Thanks guys
Northman
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Re: Piston bore clearance

#2

Post by Northman »

So your going 10 over....you are boring first then honing to size if I'm understanding correct.
I would final size the cylinders .002 over. A little extra won't hurt. Make sure to check your ring end gap.
If you've broke in a motor before and everything is in order, timing, carb settings etc. You could go less ...but my opinion is don't. Even .0025 is fine, just depends how the honing ends up. give or take.
Is 10 over going to clean everything up and straighten the way? Just asking.

Northman
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Re: Piston bore clearance

#3

Post by Excalibur »

I re-bored my cylinders using cheap repop cast pistons with .0015" clearance at bottom of skirt. 2 years and 5000 miles later, all is well.
Hope this helps.
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Re: Piston bore clearance

#4

Post by socalrider »

[quote=Excalibur post_id=115011 time=1503749572 user_id=7734]
I re-bored my cylinders using cheap repop cast pistons with .0015" clearance at bottom of skirt. 2 years and 5000 miles later, all is well.
Hope this helps.
[/quote]

Did the same thing as Excalibur. Cast pistons, .0015" clearence. Did many bench test runs before actually putting motor in frame and riding.i NEVER let the motor get over 127* during bench running ,always had a large fan blowing on it. Have got 1200 trouble free miles to date on motor and runs VERY strong. Stock stoke torque monster wheeks ,40 over pstons, linkert carb, andrews j cam,and the BIGGEST improvement velva touch guilds,lifters,push rods.
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