Piston sizes

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jimyboyle
Minor Friendly
Posts: 28
Joined: Wed Dec 14, 2011 11:07 pm
Location: Glasgow
MMOC Member: No

Piston sizes

Post by jimyboyle »

While in the middle of my 2 door restoration, I bought a 1275 midget engine to fit in place of my 1098.

The internals look quite good, big ends have been ground to -.010" and the bores show almost no wear however,
the pistons are clearly marked 0.75 suggesting 75 thou rebore.

When I measure the bores I get about 71.4mm (metric mike) which is 0.030"over standard

Would piston have been incorrectly marked? seems hard to believe.

Jim
katy
Minor Legend
Posts: 1092
Joined: Sat Mar 14, 2009 2:50 am
Location: Red Deer, Alberta, Canada
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Re: Piston sizes

Post by katy »

I don't know if it means anything, but .75mm = .0295275"
Talk slow, think fast!
jimyboyle
Minor Friendly
Posts: 28
Joined: Wed Dec 14, 2011 11:07 pm
Location: Glasgow
MMOC Member: No

Re: Piston sizes

Post by jimyboyle »

Well spotted Katy, it never crossed my mind that they could have marked the piston with a metric unit
Jim
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