A good detail to know:
Talking about ''inlet boost'' its a construction in frond off the reedblock's and between the carbs
Talking about ''spacers'' its a construction in frond of the crank and between the reedblock ( enlarging crankcase volume)
When the piston goes down, the reeds of the reedblock are forced to close (du to pressure an own construction) when the reeds are closed no airflow (mixture) can com from the carbs. When the piston goes up again reeds are opening and the airflow/mixture goes through again.
With the use of a boost construction, if the reeds are closed the airflow does not need to stop because it can flow into a certain space/room
- Boost bottle
- Connection in between
First thoughts ''this will never work'' but as always those Japanese has thought about it.
Try to blow air in a bottle its hard to do as the bottle is already filled with air and will not be easy compressed.
The hose has a certain length and is connected to the other carb. rubber.
When one side the reeds are closed the airstreams can co easily through the boost inlet as it is helped by the suction from the other carb.
The mixture stream goes into the hose for about half way, and sucked back when reeds are opening again.
-to short and it will be sucked into the other carb (it will miss his full potential)
I have my doubts if the hard plastic boost bottles will work (end 80's begin 90's)
As described above, try to blow in a hard plastic bottle it will be difficult.
The incoming airstream needs to go somewhere easily and fast (it needs to expand)
You will see that more modern bottles are made from a flexible/spring like material in order to take and release it quick
Not the most ideally one but on the 3MA easily to do and works.
When one side the reeds are closed, the airstream can go easily into the boost inlet because the other side sucks it right up.
The idea behind this, that the boost inlet starts to work agents you when you go into the higher rpm's
You have quit a big hole/construction inside the carb rubber, at high airstream speeds it can create turbulence in the airflow.
A Small note from me,
We talked about airstream, speed, flow, etc. But these constructions only works in the low RPM range.
In the RPM range where the reeds are opening and closing, ones the bike gets in his powerband and the pipes start working.
No boost construction will work
And if you want to visualize it, its not a big bucket of air that is smashed around , more a small puff off air