Pictures of Lambretta Super Monza Kit.....

[sean brady scooters]

the mixture of fuel and air is then as you say stuffed back into the boost bottle which is there to provide extra volumne then yes ?

[sean brady scooters]

lol,so lets back track a bit then ...what is it then that fills the boost bottle ?

[sean brady scooters]

well its crankcase pressure ...thats stuffs the gas back into the extra volumne of the boost bottle ..
now obsolete due to the modern use of bigger reed blocks which enable lower pcr ...cos they trap so much gasses behind them

[Chris CSPE]

It's the same amount with a boost bottle or without one, it just prevents it from being made richer from preventing it reaching the needle area, with the bottle that small amount stays at the same ratio, without it becomes richer, either way it's not a extra amount of fuel that's in the bottle and adds no more volume to the crank case.

[sean brady scooters]

lol ,ok so lets maybe agree to dis agree on this and not fall out about it ...so ask yourself why modern two strokes/crossers etc dont use the boost bottle any longer ?
and why are boost bottles only marketed on say E bay now as a solution to old bikes

and further more why arnt AF/cam lam etc etc promoting these lol

[Muppet]

the air that went in the carb and caused all the problems needing boost bottles was imperial air back in the old days; but now all the air since 1971 is metric so the boost bottle isn't needed with metric air?

muppet,

[sean brady scooters]

[Darrell Taylor]

lol,so lets back track a bit then ...what is it then that fills the boost bottle ?

when a motor is out of phase and the reed valve is closed the intake charge continues and hits the back of the reed valve and bounces back ,this charge is then drawn in the next time the reed opens and presents the engine with a double rich mixture which is especially noticeable before the motor comes onto pipe displaying itself as a cough and splutter,the introduction of the boost bottle was to capture this double rich phase which cleaned up part throttle carburation and pre pipe hicups.the boost bottle only worked when designed with a calculated volume and connection tube to time up with the out of phase rpm,around 12 yrs ago i used this system on my race bike when using an on bike dyno system which the hiccup played havoc with and it cured it and cleaned up throttle response as well so i found it worked in reallity and not just in text book
the only boost bottle i have ever seen is between carb and reed ,anywhere else is for other purposes
the boost bottle was still seen in various forms on lots of models most famously the yeis that yamaha developed,later models saw the boost boottle droppedbut had improved carb/reed designs but most importantly better ignition advance curves that cleaned up that out of phase area and produced better power to boot (eg the effect you feel when fitting an augusto/ m tech/varitronic etc)
crankcase volume,now thats aother story
please feel free to move this post as its way off topic

[Muppet]

Yup usually mounted on the carb rubber that sits just before the reeds; but how does it know what it has to do and when; Answers on a postcard in no more than twelve words, winner receives ten brownie points,

muppet,

[Muttley McLadd]

now all the air since 1971 is metric so the boost bottle isn't needed with metric air?

muppet,

The list of things we can thank the Romans for is never ending!!