ES 250/2 gearbox sprocket

[liquidgold]

I will shortly require a new gearbox sprocket but seek advice as to the right one. Twenty five years ago I ran one of these bikes and always thought it was slightly over geared with the standard 21 tooth sprocket. I know there is a big gap between 3rd and 4th gear which will remain but is there any advantage in running a 20 tooth sprocket to bring the revs up a bit? Anyone with any experience of playing with sprockets? John

[Puffs]

Removed