Whitworth Fasteners?

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Yes there is it screws into two 5/16 holes on the engine sprocket
Easy to make if you have facilities you can also use a 3 legged puller if you remove the primary chain I seem to remember?
5/16" UNF on the triplex sprocket.

Not appropriate to the OP, but I have a Bob Newby belt pulley, which replaced a Norman White belt pulley....Bob uses M8, Norman uses 5/16" UNF....always check the thread on non-standard parts.
 
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5/16" UNF on the triplex sprocket.

Not appropriate to the OP, but I have a Bob Newby belt pulley, which replaced a Norman White belt pulley....Bob uses M8, Norman uses 5/16" UNF....always check the thread on non-standard parts.
Yep always best to check
I have a norvil belt drive and the holes are 5/16 unf
 
If you haven't pulled a commando primary before there's a couple of things to watch on re assembly
Make sure the inner chain case is shimmed on the centre stud
Make sure you replace the tab washers on the inner chaincase or loctite or both
Always replace the mainshaft clutch circlip and check sprocket alignment
Throw away the clutch tab washer and use loctite instead
Also the workshop manual torque setting for the clutch is far too high
But I can't remember the setting now recommended
Also the the alternator stator absolutely must have the 8 thou air gap
Don't over fill with oil (ATF) when refill it
As has been mentioned before it's really not hard to change the layshaft bearing in the bike
Unless you want to strip the whole lot out to check the whole lot out (not a bad idea IMO) then maybe just change the bearing and inspect for other damage
Also, use some RTV on the threads of the three crankcase mounting bolts to keep engine oil from weeping into primary.
 
Something I was told years ago was when heating something round to release it you should only one spot because it expands and breaks it grip better than heating the whole thing with the resultant heatsoak into the shaft you are trying to remove it from?
Never tested it, I wouldn't refute it. Yes, heat transfer happens, BUT, often overlooked is the thermal conductivity to the heat SINK. Small sprocket in air, a great insulator = almost dead end heat sink, vs, entire crankshaft connected via steel to the taper of the shaft. Rate of rise. Get the puller beaming tight, heat that sprocket fast & furious.
 
5/16" UNF on the triplex sprocket.

Not appropriate to the OP, but I have a Bob Newby belt pulley, which replaced a Norman White belt pulley....Bob uses M8, Norman uses 5/16" UNF....always check the thread on non-standard parts.
How does the pully ratio compare to stock triplex sprockets?
 
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