Popping out of first on rare occasion

Well whenever I start my 73 850 Commando, on occasion it jumps out of first gear when setting off, after the inital setoff things are fine. I did research on this, and measured how much endfloat I had on my kickstarter with my dial gauge, which worked out to be around .0017. Researching the forum I found that using rear isolastic shims would take up this slack, but what would the optimum endfloat be? I am guessing between .005 and .0010 from other posts, I just want to confirm. Also, From that I can tell the shim will mate up just between where the kicker quadrant meeting the layshaft bearing, is this correct? Thanks for all the help, I know Triumph 650's pretty well, now I am learning Norton's.

My Commando used to do that occasionally until I changed the layshaft 1st gear bush that was beginning to break up and move out of position so that could be something else to check.

The hair spring in the inner case might just need a slight adjustment, Nortons seem to like a bit of endplay in everything.

This gearbox needs the layshaft to be shimmed ALA Old Britts . Use isolastic shims , trimmed or ground a bit where the correct thickness shim could hang up on reassembly .. The goal is just enough to prevent any slop , but not too tightly shimmed , to possibly prevent the kicker return to work freely .
That said after 4 Nortons , I've removed my kicker . E- start from here on in , at age 68 .
Mind you the layshaft is shimmed .
The most important thing is the roller layshaft bearing ( replacement ) . That requires the shimming , timing side .
Another factor is the first gear bush . Very small and delicate . Replace it without thinking , as all is apart . Use heat and the
frozen new bush to fit . Tap in carefully , or a light press if you have one .
Good luck , enjoy .

ashman said:

The hair spring in the inner case might just need a slight adjustment, Nortons seem to like a bit of endplay in everything.

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It was the hairpin spring on my commando when it jumped out of first gear