The four ways you've listed are rarely the case in mopeds. The restrictions are usually in
1. carb body bore(lke the 14/12 Dellorto)
2. Intake, (like the Bianchi Snarks 7mm manifold)
3. porting(sachs "A" cylinders) or
4. exhaust headers restiction(some sachs especially)
The only "washer" i've removed from a moped was the intake restrictor on my Derbi, and that was only there to match the 12mm DEllorto to the 15mm manifold.