The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: jachenbach on 08.02. 2015 01:17
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Been going crazy trying to find a spec that makes sense for rod bearing journals. By the numbers in Haynes and the chart found in a service sheet on this forum, and the service sheet on regrinding crankshafts, it would seem they start at 1.45 inches. I've measured 5 of them that I've had here. 4 of them measured 1.66 with a caliper. The one for the Spitfire (that I intend to use) measured 1.68 with the calipers. I got the Starrett micrometers out and measured both journals and got 1.686 inches both journals nice and concentric. I'm guessing this crank may be original size and others were reground .020 undersize, but why can't I find this info anywhere???? After looking it over more closely, I'd like to at least get it polished and put fresh bearings in, but without the starting size I don't know what bearing to order.
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G'day jachenback.
A7 (short stroke) and small journal A10 are 1.460". Large journal A10 are 1.687".
http://www.srmclassicbikes.com/technical/bsa-a7-a10-big-end-journal-sizes
Not sure about the long stroke A7's.
Cheers
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Longstroke same as short stroke