| Diagram | Fig. 5 — 850 Engine: Crankcases, Filter, Breather, Tachometer Drive · ref 27 |
| Subsystem | engine bottom |
| Listed in parts books | 1973 |
Norton Case stud, rear (4 in.)
A 4 inch rear case stud for the bottom end of the engine, PN 064157.
This is a case stud, rear, 4 inch, part number 064157. It's a crankcase stud that lives in the bottom end of the engine, per the parts-book figure covering crankcases, filter, breather, and tachometer drive. Studs like this hold the crankcase halves together and give the covers something to bolt down to.
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The catalog record we have only shows this part appearing once, tied to the 1973 model year, so we can't speak to broader fitment beyond that single listing. If you're matching up a stud for a rebuild, check the length and thread engagement against what's coming out of your cases before you order.
Call the shop if you want us to confirm this is the right stud for your crankcase before it ships.
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