Kick start spring help splitting engine case

[BalideyUK]

Hi all,
I have a 1939 BSA B21 De Luxe 250cc that is new to me.
Kick start spring is broken and I have a replacement.
I followed the manual I have as best I could, getting to this point in the photo, but I can't get the inner case apart.
I have tried gently chapping it off from the left side but no movement.
I have kept the gearshift mechanism in place as the manual suggests and the screws holding this inner case are removed.
A friend who ran Bantams suggests applying some heat and continue chapping from the other side.
Is this correct, or is there a trick I am missing?

Thanks in advance for any help.

[militaryron]

You need to remove the gear change mechanism, especially that nut on the end of the selector shaft. That actually looks like a later M20 gearbox.  I have the work sheets for the M20 box, which ought to be studied before assembling. Ron

[BalideyUK]

Thanks, when I get to the workshop I'll try with that nut off.

[militaryron]

Let me know if you want a copy of the M20 service sheets

[BalideyUK]

Got the case apart. There was a third bolt hiding behind the linkage!

militaryron, yes please, if you could share the service sheets that would be a great help, thanks.
Can you attach them to a message or do you need me to send you my email address?

regards, Steve

[militaryron]

I sent a PM with my email address. Ron

[Group Leader]

Funny enough I've just had to replace my kick starter return spring.   

I found it quite tricky getting the 1/2 turn of pre-load on re-assembly.  It needed a suitable tool for the screw driver slot and another pair of hands.    We managed to use a bit of plate and some Molegrips.  If I have to do it again I'll make a proper tool from bar material with a suitable "blade" on the end with a centering spigot and a hole for a Tommy Bar at the other end.

It seems to me that the design of the spring/quadrant gear is very poor; the coils get displaced as it rotates as the tang/end of the spring is only partially retained in/against the quadrant gear and the part of the spring that actually takes the load bears on a sharp corner on the gear.    The broken spring shows extensive wear on numerous coils.   I wonder were all that metal went?  Oh, I know, in the gear box.    Still it's a bit late to query the manufacturer I suppose!

Alan