How many engines use this basic system of intake and exhaust...not many.. Most engines run with a reed valve system, which is much better.
boost bottles
- Thread starter rickie h
- Start date
Well dang it all, I am feeling just as dubious about the boost bottle as before. I read somewhere once, in reference to "cures" for ailments, something like: "If there's a hundred different cures for a disease, you can be sure none of them work"
I guess I'm saying that if there is still this much debate about whether these things actually work, they probably don't. I mean, nobody argues the merit of expansion chamber exhausts, by comparison.
The boost bottle will likely just stay in the drawer for now, though I look forward to reading more from others on their results from trying them.
Thanks again for the feedback, Brosephs
I guess I'm saying that if there is still this much debate about whether these things actually work, they probably don't. I mean, nobody argues the merit of expansion chamber exhausts, by comparison.
The boost bottle will likely just stay in the drawer for now, though I look forward to reading more from others on their results from trying them.
Thanks again for the feedback, Brosephs
Hey - don't let us discourage you from experimenting if you've got one already anyway lol, if nothing else they look cool and will be sure to impress anyone other than a die-hard 2smoker motorhead 
Heck, I've seen ppl spend a LOT more time, money and effort on "upgrades" that may be nothing more than cosmetic - shucks, everyone knows even jus' a few stickers makes ya go faster
Heck, I've seen ppl spend a LOT more time, money and effort on "upgrades" that may be nothing more than cosmetic - shucks, everyone knows even jus' a few stickers makes ya go faster
Yeah, we'll see.. I don't want to screw up an otherwise strong and reliable bike either.
I thought I saw some boost bottles on bigger two stroke motorcross type bikes a while back.. Anyone seen any on bigger displacement bikes?
I thought I saw some boost bottles on bigger two stroke motorcross type bikes a while back.. Anyone seen any on bigger displacement bikes?
Just read this on a fellow's two stroke tuning business website:
2-stroke-porting.com - Computer Designed Tuning
Boost Bottle
How does a Boost Bottle improve performance? Air rushes thru the carb on the intake cycle. Ignition accelerates the piston down, forcing the reeds to snap shut. The momentum (inertia) of the air has to go someplace. It goes back thru the carb causing a double rich mixture. The result can be rough idle or hesitation.
Due to the high velocity of the fuel air mixture through the carb boot, we need to take advantage of this momentum/inertia energy. The Boost Bottle and tube provide storage for the fuel air mixture between carb boots. The energy (pulse) forces the pre-atomized mixture in the tube from the previous cycle into the adjoining carb boot where the reeds are just opening and ready to receive the fuel air mixture. The boost bottle and tube provide a "boost" supercharge effect to each cycle.
The boost bottle is most effective at lower and mid-range rpm, and, when you are on & off the throttle. It assists in filling the cylinder (shorter distance) for a fraction of a second until the carburetor venturi gets enough velocity to fully atomize the fuel. The advantage is that it brings up the torque and horsepower in the bottom of the rpm range, up to where the pipe(s) starts to work. There is a small benefit at high rpm's.
What Size? Singles = usually the CC of one cylinder or larger. 700cc Twins = 300cc boost bottle. 700cc Triples = 225cc.
Variables: Engine CC's, Carb Size, RPM below pipe, Number of cylinders. Large carbs like larger bottles/tubes. Triples like smaller due to less time between pulses.
I use the TSR computer software to calculate the Boost Bottle for a specific set up.
Yes they work, when the size is right, the inertia of the air is stored like a spring in the boost bottle to help charge the next cycle. Try tuning a Yamaha Phazer without it's boost bottle!
Power valve engines may not have similar performance gains because the valves will keep the bottom end crisp. Testing w/ powervalves will probably show gains off idle and low bottom end. Is it worth it?? That depends on what you are willing to pay for some torque and a couple of horses!
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2-stroke-porting.com - Computer Designed Tuning
Boost Bottle
How does a Boost Bottle improve performance? Air rushes thru the carb on the intake cycle. Ignition accelerates the piston down, forcing the reeds to snap shut. The momentum (inertia) of the air has to go someplace. It goes back thru the carb causing a double rich mixture. The result can be rough idle or hesitation.
Due to the high velocity of the fuel air mixture through the carb boot, we need to take advantage of this momentum/inertia energy. The Boost Bottle and tube provide storage for the fuel air mixture between carb boots. The energy (pulse) forces the pre-atomized mixture in the tube from the previous cycle into the adjoining carb boot where the reeds are just opening and ready to receive the fuel air mixture. The boost bottle and tube provide a "boost" supercharge effect to each cycle.
The boost bottle is most effective at lower and mid-range rpm, and, when you are on & off the throttle. It assists in filling the cylinder (shorter distance) for a fraction of a second until the carburetor venturi gets enough velocity to fully atomize the fuel. The advantage is that it brings up the torque and horsepower in the bottom of the rpm range, up to where the pipe(s) starts to work. There is a small benefit at high rpm's.
What Size? Singles = usually the CC of one cylinder or larger. 700cc Twins = 300cc boost bottle. 700cc Triples = 225cc.
Variables: Engine CC's, Carb Size, RPM below pipe, Number of cylinders. Large carbs like larger bottles/tubes. Triples like smaller due to less time between pulses.
I use the TSR computer software to calculate the Boost Bottle for a specific set up.
Yes they work, when the size is right, the inertia of the air is stored like a spring in the boost bottle to help charge the next cycle. Try tuning a Yamaha Phazer without it's boost bottle!
Power valve engines may not have similar performance gains because the valves will keep the bottom end crisp. Testing w/ powervalves will probably show gains off idle and low bottom end. Is it worth it?? That depends on what you are willing to pay for some torque and a couple of horses!
--------------------------------------------------------------------------------
Quality Workmanship
Lowell Horning
Contact Me Here
--------------------------------------------------------------------------------
[HOME] [Computer Design] [Altitude & Air Density] [BMEP] [Boost Bottle] [Carb Flow]
[Porting Pics] [Squish Test] [Tuning Help] [Terminology] [Request Form] [Picture Gallery]
Another tuning resource which attempts to illustrate the theory behind the boost bottle:
Boost Bottle - Wikiscootia - A scooter wiki
Boost Bottle - Wikiscootia - A scooter wiki
I've seen quite a few off-road 2-stroke cycles with a "boost bottle" of sorts. They're usually cunningly hid or made part of the airbox. They do indeed work, but how much so depends on how well it's matched to the engine and intake/exhaust.
I made a couple of 2" PVC bottles and played around with them for awhile and noticed more midrange power and smoother acceleration once it was "charged".
I made a couple of 2" PVC bottles and played around with them for awhile and noticed more midrange power and smoother acceleration once it was "charged".
I'd hafta see a factory install... I usta work at a motorcycle shop that did a lot of motocross bikes - and I don't remember ever seein' one of 'em with a "boost bottle" as described here. Granted, it was quite a while ago and my memory... isn't lol - but I think I'd remember something like that if they were commonplace.
See where all the above theory starts to fall apart is pretty much simple flow dynamics - like just about anything, the air/fuel is gonna follow the path of least resistance and that's gonna be out the open end of the carb. These "boost bottles" all rely on "storing" some sort of pressure between pulses, which would require it to pressurize - which I just can't see happening. Picture trying to blow up a balloon with a T fitting on it that's open on one side, balloon & you on the others, ALL the "pressure" would just be vented out w/nothing to speak of in the balloon (unless there were disproportionally sized ports, a very small one open and a larger one to the balloon, but that's the opposite of what the boost bottle has). It is conceivable that it could pressurize were it between a reed valve & the piston... but that's not how it's promoted nor would it be needful.
I suppose there could be some small vacuum created in the bottle via the venturi effect, which could draw in some fuel/air charge in the moment when that intake vacuum was reduced... but not only would that be so insignificant an amount as to be irrelevant (as it would simply revert to normal atmospheric pressure, not provide a "boost"), this is not how it's illustrated as it's function or purpose as described by it's proponents and advertisers... If we start seeing a change as to how they're advertised to what I just described... well, we'll know they're readin' our forum anyway lol
Speaking of which - generally speaking advertiser's claims are to be taken with a grain of salt as they're promoting & 2-stroke-porting.com - Computer Designed Tuning is most definitely an advertiser. Boost Bottle - Wikiscootia - A scooter wiki is obviously not trying to sell their services and you'll notice their entry is sprinkled with conditioners, like "theoretically" & "vehemently debated".
I think huckersteve expressed it best when he stated: "I guess I'm saying that if there is still this much debate about whether these things actually work, they probably don't. I mean, nobody argues the merit of expansion chamber exhausts, by comparison."
See where all the above theory starts to fall apart is pretty much simple flow dynamics - like just about anything, the air/fuel is gonna follow the path of least resistance and that's gonna be out the open end of the carb. These "boost bottles" all rely on "storing" some sort of pressure between pulses, which would require it to pressurize - which I just can't see happening. Picture trying to blow up a balloon with a T fitting on it that's open on one side, balloon & you on the others, ALL the "pressure" would just be vented out w/nothing to speak of in the balloon (unless there were disproportionally sized ports, a very small one open and a larger one to the balloon, but that's the opposite of what the boost bottle has). It is conceivable that it could pressurize were it between a reed valve & the piston... but that's not how it's promoted nor would it be needful.
I suppose there could be some small vacuum created in the bottle via the venturi effect, which could draw in some fuel/air charge in the moment when that intake vacuum was reduced... but not only would that be so insignificant an amount as to be irrelevant (as it would simply revert to normal atmospheric pressure, not provide a "boost"), this is not how it's illustrated as it's function or purpose as described by it's proponents and advertisers... If we start seeing a change as to how they're advertised to what I just described... well, we'll know they're readin' our forum anyway lol
Speaking of which - generally speaking advertiser's claims are to be taken with a grain of salt as they're promoting & 2-stroke-porting.com - Computer Designed Tuning is most definitely an advertiser. Boost Bottle - Wikiscootia - A scooter wiki is obviously not trying to sell their services and you'll notice their entry is sprinkled with conditioners, like "theoretically" & "vehemently debated".
I think huckersteve expressed it best when he stated: "I guess I'm saying that if there is still this much debate about whether these things actually work, they probably don't. I mean, nobody argues the merit of expansion chamber exhausts, by comparison."
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Speaking of the flow dynamics no body ever has any testimony with a reed valve combination bet that changes things. Don't know never tried but have always though about that.
Well now that I think about the dynamic part of things there would be only so much air fuel mix going into the engine. There would be no performance at higher RPMs. So a guy gets a slightly improved Idle or mid range? 
Just thinking through the key board here.
I used one for awhile on a china That's all I got from it nothing really dramatic. It was just a bit smoother off idle was all. No power increase.
Just thinking through the key board here.
I used one for awhile on a china That's all I got from it nothing really dramatic. It was just a bit smoother off idle was all. No power increase.
Well, That does it for me- I'm going in. I won't find out a darn thing without trying it myself at some point. Intake is already off the bike. Will report back soon.
We put a double boost bottle/nitrous kit on my buddies bike and he has a pull start. Used to start on 1or 2 pulls now with the bottles it is about 20. Once its running seems like it has to fill up the bottles before running smooth. Ran good and the nitrous worked but he doesnt like having to pull his guts out trying to start it. I told him to put a couple valves inline to close em off till it was running and open them up when he wanted nitrous.Thats what im gonna do..
has anyone installed a kit with a shutoff valve yet? i think that would would be the way to go for a direct comparison. i think its a sound theory. it is, after all, basically a pulsation dampener. we all know that smoother is better and the smoother airflow thru the manifold will help the fuel atomize better. my main concern here is the restriction caused by the threaded nipple. i cant seem to find any tapped manifolds that have a welded nipple so that the id can stay the same. whats the point of recycling backpressure if you have to restrict flow in the process
I put them in my intake and just used a dremel tool to smooth it up so it wouldnt interfere with airflow. tuned pipe is the best money but i already have these or i wouldnt bother putting them on..
The boost bottle is supposed to work best in conjunction with a tuned pipe. It's not an either/or thing.
Well, here's the thing, not that I hold either one of the guys who wrote the books in the links of my signature to be gods, but they did know what they were doing. I read both books front to back, guess what, not one mention of boost bottles. I don't think that is a coincidence. There are SO MANY other ways to get more power from the HT's. Read their books and then get out in the garage
