Head removal - What size are those nuts?

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Jan 8, 2006
Hi All,

Can someone please inform me what size spanners and socket(s) I need to remove the head and barrell?

I have AF and Metric, none of which fit, I notice there are a few different sized nuts to be undone, any help would be much appreciated.

Thanks, Vince
Vince you need some 'Whitworth' spanners and sockets 1/4", 3/16' and 5/16" are useful for the job you mention. Be aware that there are a total of 7 fasteners that hold the head on from the top and 3 from the bottom. At the front of the head there are two nuts recessed into holes on either side of the rocker box castings, however less obvious is a single bolt further towards the back of these rocker housings deep down where the exhaust rocker box castings converge in a 'V'. This bolt has probably been responsible for more broken fins on Nortons than any other factor, as lots of people assume thay have loosened everything and the head is merely stuck to the gasket when in fact it is still firmly bolted together. Additionally you may find that you have to remove one or two rocker shaft plates in order to fully remove all the 4 side top bolts from the head. If you are taking the head and barrel off in the frame you should slacken the tappets and hold all 4 pushrods into the head as you remove this assembly. Good luck
It takes a thin ring spanner for the rear nut below the carburetors (don't use an open-end here!) and a thinwall socket for the nuts between the exhaust rocker covers and central top bolt. I have an angled ring spanner (box-end wrench) I bought years ago that makes the rear nut and nuts under the exhaust ports much easier to access. I also find that my inexpensive Kokon (Japanese) whitworth sockets fit the headbolts better than my Snap-Ons, because they are thinner.
Yes, they are available from many of the British bike parts suppliers for about $40 US. I highly recommend you buy a set of whitworth sockets and combination wrenches before tackling major engine or gearbox work. Most other nuts and bolts on a Commando are standard SAE sizes.
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