Honda CB 250 RS project kick start clutch lock problem

[K2-K6]

Ordinarily, with the plates removed from clutch, then the gearbox is removed from equation as with the drive to gearbox now detached.

Date knows more about layout than me specifically for this engine though.

Generally, design  of bikes has kick onto clutch basket and then to crank, not via gearbox. That so you can kick them over in gear while pulling clutch lever to start, meaning you don't have to select neutral.

[Bryanj]

Yes you have "primary kick" where you can pull clutch in and start engine or "secondary kick" where if you pull the clutch in the kickstart does nothing.
The crank turns the basket on a bush on the shaft, there should be thrust between clutch basket and clutch inner, without this the gearbox locks, try looking at a parts diagram on cmsnl to see where all the parts go, it is possible in some Hondas to fit a bush in a gear the wrong way round which will also lock the box when thongs tightened.
This is one of those where if its in front of you it may be obvious but long distance over the net is very difficult

[CMXCol]

OK

Fixed it.
The issue was very difficult to pin down I had to rebuild the gearbox twice to find it.
On the balancing weight end of the clutch shaft opposite the clutch there is a needle roller bearing it has a thrust washer, (red arrow) the bearing outer shell also has a hole which locates on a dowel pin (blue arrow) in the bearing mount.
The thrust washer pushes into a thin housing, a thin recess, just before the bearing mount with the dowel.
If this thrust washer is not seated correctly even with the casings closed it can cause the bearing to not quite seat correctly now that doesn't expose itself until the engine is put in gear, any gear, the very slight misalignment causes the gear train to lock I noticed even when the gear selector was in the neutral position it was still locked in gear, the drive sprocket wouldn't even turn making it impossible to turn with the kick start in neutral once the gearbox locked.
Picture of offending items "arrowed" attached, just one little washer caused all of that grief.

[Johnwebley]

Well done

Sent from my SM-A546E using Tapatalk

[Bryanj]

One of those " gotcha you barsteward" moments

[McCabe-Thiele (Ted)]

Pretty impressive that you found the cause of the problem, well done.

[Laverda Dave]

Good news and a simple fix in the end with nothing broken or seized.