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Very little adjustment either way on this offset pin. I have gained a little bit in the upshift direction where the problem seemed to be. Going to get it round the block later today, see if it’s made any difference.
 
 

The TY250 is very similar to your bike. Very commonly the stop/adjusting pin boss, is broken out of the case, when the gear lever hits something solid like a rock.

Have you taken the pin out and checked if its straight? If its bent, might be causing your problems.

Not bent but I’m feeling like the sum of wear in the multiple pivots of this design could add up to insufficient final travel of the claws. Maybe a bit of pin shaving to allow that little extra bit of travel, or bad idea ?

Unlikely to be much wear, as all the parts are working in oil, and not under a great deal of strain. Has anyone replaced the neutral finder detent spring, with something much heavier than it should be?

That’s a possibility although I thought that pin does nothing more than retain the drum in the right position ?

If the spring is too strong, then shifting will be harder.

Don't shave the pin--as you said. Just shave the arm where it stops against the pin.
Few wipes in the direction you want more travel using a good sharp file.
But i'm "not recommending that" as don't think its your problem.
When i did that i got false neutrals between gears in a racing situation. Mine was just rounded off dogs & dog slots climbing out. Yours might be something else entirely.

I would like to add my experience on this topic. I have 5 250s and 4 360s that are regular riders. Some are original, some are restored, some are repaired. All the 250s run, clutch and shift smoother than the 360s.
I have 2 spare 250 motors and 1 spare 360 motor. If and when I get time I plan to take them apart and see if I can put a 250 transmission in a 360 and if so put the 250 transmission in one of my 360s to see if it makes a difference.
Has anyone tried this?
 

Some things to be aware of are--the early DT1 had the 4th/5th selector wrapped around the drum & i don't think the first 360 had that [360 went conventional from the start]. So "if you have an early 250 motor" it might all swap into the 360, but early 250 case won't have the case hole for the 4th/5th selector shaft when swapping the 360 in.
Looking at Partzilla "that'' system [wrap around selector] didn't change in 250's until "72 with DT2.
360 never ran that setup.
Partzilla might have it wrong so just be careful that's all.
I can't think of a logical reason for the 250 shifting easier.
Man you're keen with all those 250 & 360's--not enough days in the week haha.

RT325 said:
Man you're keen with all those 250 & 360's--not enough days in the week haha.

Yes, and they all scream at me when I walk in the garage "Ride me...Ride me".