BOOST BOTTLES Learn about them Here!!!

A small bottle ,often called "boostbottle", is installed between the carb and the intake port connected with a branch pipe to get the engine to respond quickly from bottom end without flat spots.
It saves 10-15% in gas consumption and makes the engine wake up at lower rpm.

Like many of Yamahas inventions. When it first came out there were many doubters. Just as they doubted the wisdom of a separate oil pump and the 7th port. Or Torque Induction. But if done properly this does work.

The following diagram shows a typical Y.E.I.S setup. The most common mistake people make is not placing the boost bottle above the cylinder, not getting the size right and using a common bottle for two cylinders and failing to make sure that the bottle drains back without collecting fuel.




Since Carburators can carburate both in and out, when the charge is out of
phase with the engine it creates a double dipping intake charge (passing the
jets twice). This kills the engines ability to make Torq due to this RICH
condition, thus creating the Torq\HP DIP just before the engine starts to
take in the charge and use it all. This Power dip can be seen in both 2 and
4 stroke engines. The ~BOOST~ Bottle will help cure the problem by providing
a storage tank, of the required volume and distance to resonate at this RPM.
It stores the charge that once reversed back through the carb and returned as a DOUBLE RICH condition.

Hope this helps :wink:[img][/img]

i got no idea what the f*#k you just said lolol

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Queensland Motorcycle Riders Forum

LOL BUNG :roll:
In Caveman speak it makes it go hard UGH UGH!!!! :P

in simplest terms it will improve throttle response and mid range with a little help on the top end :wink:

so what are the parts required to setup this?

ive got a 49cc Chinese Pocketbike....the tiny ones

in my particular situation, ive just newly acquired a walbro carb (WYK), the ada mount for it, & ada filter.

Oh and most importantly...the price


cheers

alex

ive got a yz 80 97 model, im my garage getting a new clutch at the moment. it has the boost bottle on it.
i think what the guys at oz scoot were trying to tell you is that when your reeds close a back pressure wave travels back up your intake. the boost bottle collects some of this pressure. at higher revs the pressure stays more positive because the slide is open further air velocity is greater and the reed valve is opening and closeing at a a much faster rate so since presure waves travel at the speed of sound, depending somwhat on your complete induction system design, the back pressure dosnt have time to travel back up the carbie before the reeds open again.
but when you shut off the throttle there is a sudden drop in pressure. revs drop due to lack of mixture. and the engine feeds off only what is going through the slow running system of your carb and what is getting under your slide. at these rpms the intake charge in your crank case that is suposed to be going up your transfer ports wants to flow back into the space between your carb and reeds more than ever before your reeds snap shut. the pressure in your boost bottle is now higher than in your intake manafold so the pressure feeds back into the manafold from the boost bottle instead of from the crank case. so when you crack open the throttle the pressure in the manafold is allready high, and the engine is a little quicker to respond, but you dont want the pressure to oppose your intake charge at this point. that is why bottle volume, and the size of the opening at the manafold are so important, the whole intake system needs to be tuned with it.
how well it works or weather or not its practical to use with any one particular engine design depends on alot of things. i dont think it has its place on every engine.

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still didnt get a price though did we ?????lol

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Queensland Motorcycle Riders Forum

I have em starting at $65 even got a double billet PBU set with predrilled manifold but you better sit down and call for the price on that one :wink:

IN MY EXPERIENCE

They work well on Piston Port motors but have to set up perfect to have a still minor effect on a reed.

The reeds close and stop the carby "exhausting" much so the effect is no where near as pronounced as on a piston port.

The piston ports even benifit from a "tuned" size air box where the reeds tend to want to breath.

So if you have one of those mid size bikes with the piston port engine it's probably worth trying.

They cost you top end on all 2 strokes. Just depends what sort of power you want.

Some tunners claim they simply "bandaid" a poor inlet system but the theory is sound (pun intended)

PBU do kits with 1 or 2 bottles

Search the net guys , there is tonnes of info on them.

8)