Topic: Advance retard unit removal

[seabird]

I'm in the throes of replacing my clapped-out Pirhana/Newtronics Electronic Ignition system with a Boyer-Bransden Microignition system.
I've sorted out the wiring, and am attempting to remove the advance/retard unit with bob-weights etc., as the new system doesn't use tem.
I'm at the stage of attempting to slacken the small 10mm bolt (and after, the larger nut) on the end of the crankshaft, but try as I might I can't undo the small bolt as the crank keeps turning.  I put the bike ('75 CB400F) in 1st gear and wedged the rear wheel, but the damn crank continues to turn.

Any handy tips on removal of the offending bolt/nut?

Thanks in advance,

Seabird

[Tim2005]

Er, have you tried putting a ring spanner on the bigger nut behind it & holding it still with that?

[supersport_CB400F]

Get your missus to sit on the bike with it in gear and  get her to hit the rear brake, if you don’t have a ring spanner.