Hole in the side...
 

Think the hole is to there to allow adjustment of the "trim" on the ECU - i.e. the closed throttle mixture with a long screwdriver.

Charles

Ahh! And since the seat on the SP is easier to remove, it doesn't need the access hole. Makes sense I suppose!

Talking of 'trimming' the ECU...
When 'fast-riding' my Strada, I discovered it's better to ride with the cold-start device left on its first notch. This means the revs don't drop quite so low when gearing down on approach to roundabouts etc., and this in turn makes it less likely to become unsettled. (The cold-start device is not a 'choke' as such, so the mixture isn't enriched by doing this).

Who needs a slipper clutch?! (Anyone else tried this..?)