The well know ''inlet Boost'' is a option witch can help a 3MA.
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)
A small description about how it works.
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
(That inlet to that room is placed just in frond of the reeds) when the reeds open again it sucks the mixture in frond of the carbs and boost construction. Witch will gain you extra power in the low rpm's. Also a important point is that the flow does not stop when the reeds are closed so its easier to get going again.
Like to point out four options for the 3MA
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.
The length is the key to this as this is the place where the mixture stays.
The ''boost bottle''
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
You can experiment with different sizes off bottles, how bigger how easier for the airstream to compress, the more rendement you will get
The ''connection in between''
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.
There is not really a boost its only helping to get the airstream going, and that is a big plus.
The ''plugged off reed rubber''
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.
Like a GP bike, they don't have the boost bottle either.
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