I mistakenly removed this screw to clean it up and disturbed the locknut setting. The g’box is fully assembled. How can the setting of the screw be re-established without dismantling the box?

Think this needs to go into the Tech section either by a moderator or a quick cut and paste on your part.
Which bike is it in? May be relevant.
Sadly I don’t know the answer to your question
All the best
Steveguzzibrat2014-10-05 18:00:54

From the post title, its a V50. I think it might be a gearbox out job if it’s like the big blocks. I have never been inside a small block gearbox so couldn’t say for definite.

Does the gear change return spring still work? If not then it was this screw that anchored the spring and, like the big blocks, g/box end cover has to come off to put spring back on correctly. Think that’s right?

The screw adjusts the selector mechanism as it does on the big blocks. However, you cannot simply remove the end case as you can with the big blocks you have to remove the gearbox and disassemble from the clutch end. This requires special tools. There is a useful off guide to the process at the “thisoldtractor” web site in the guzzitech section. Given this, I would carefully attempt to relocate the screw testing things at every stage, you might get away with it.

Where are you located?