the yeis is not that special as people think. Its just an expansion tank to take up the inertia of the mixture as its flowing into the intake and the intake port closes.
This mix is then sucked in by the boost port as the engine comes onto pipe and the exhaust expansion chamber starts its sonic activity. This slightly widens the torque band
The YB100 has a disc valve - there is no way you can add a boost bottle to it. At best you can reshape the valve and the port on the engine so it opens suddenly rather than slowly. The suddenly opening valve amplifies the suction signal and provides more mixture to be pulled in. If you are really hardcore you can reshape the intake port upwards so the mixture rams underside the piston - this provides a smoother and faster flow into the crankcase. This way the engine will sort of supercharge itself better when the engine comes onto pipe.
If you want to understand the activity of the boost port on a rotary valve engine then look at a kawasaki KH125 (GTO125) engine, its rotary valve has a hole on the opposite side of the valve, this hole is for the boost port kick.
Do not try to add to a 2 stroke engine, its a very delicate balance on which it works, meaning if your exhaust is not correctly shaped and tuned to the transfer and boost port mapping and also your carburettor setting then you can very easily destroy your engine.
If you want the crazy supercharged pull from your 2 stroke then start with learning the engineering on how the engine actually works. Its addictive as it can produce phenomenal power.