Boost bottles?
- Thread starter 2wheel lizard
- Start date
there have been many threads on here with the same question, but generally you will get mixed results. Welcome to the forum and for future reference, the search tool at the top of the screen will help you find tons of threads answering the same question you might have, it save a lot of time on your side because you don't have to wait on people to respond. Here:
boost bottle - Google Search
boost bottle - Google Search
They're only supposed to 'smooth out' the throttle response on 2 cycle engines; (not boost power.) but they do very little on our chinese engines. 
i put one on mine and new air filter with a new msd plug wire and runs the same dam way. dont wast your money
A boost bottle's effects are subtle at best. They are intended for Hi Performance motors and work best in a package of mods. The more power a motor makes the more things like boost bottles and tuned intakes work.
What a boost bottle works on is the pressure of reversion where when the intake port closes the fuel/air mixture hits it at supersonic speed and with nowhere to go it turns around and tries to go back to the carb. The pressure spike resulting is what the boost bottle smooths out. The position of the mounting hole for the bottle is very important in the smaller motor. The Pirate Cycle's CNS carb intake is not drilled for a port. The hole needed to screw in the adapter is 3/8ths of an inch and the nipple is self-tapping. I drilled my hole at about a 25 degree angle towards the port where on the inside of the intake there's a taper. This tapered section is where the hole needs to be, The pressure from reversion is highest there . I just laugh at the stock intakes that have the boost bottle set-up. Those do not work at all.
Just like everything else proper use brings maximum benefit
What a boost bottle works on is the pressure of reversion where when the intake port closes the fuel/air mixture hits it at supersonic speed and with nowhere to go it turns around and tries to go back to the carb. The pressure spike resulting is what the boost bottle smooths out. The position of the mounting hole for the bottle is very important in the smaller motor. The Pirate Cycle's CNS carb intake is not drilled for a port. The hole needed to screw in the adapter is 3/8ths of an inch and the nipple is self-tapping. I drilled my hole at about a 25 degree angle towards the port where on the inside of the intake there's a taper. This tapered section is where the hole needs to be, The pressure from reversion is highest there . I just laugh at the stock intakes that have the boost bottle set-up. Those do not work at all.
Just like everything else proper use brings maximum benefit
Last edited:
Hey DaveC...got a pic of that Boost Bottle install?
Also, did you mean you did not drill your hole perpendicular to the intake surface, but actually at a 25 degree angle toward intake?
Didn't that screw up your 'seating'/sealing of the hole or not so much?
Thanks!
PS: Does it work well?
Also, did you mean you did not drill your hole perpendicular to the intake surface, but actually at a 25 degree angle toward intake?
Didn't that screw up your 'seating'/sealing of the hole or not so much?
Thanks!
PS: Does it work well?
A boost bottle is designed to increase the smoothness of the engine at lower speeds and idling NOT TO BOOST POWER though this can be a noticeable side effect (2-4 mph at best).
These are so controversial because the websites that people buy them from hardly ever ship the right volume bottle and cause people to think they dont work. I bought mine from a site boostinductionsystems.com and they sent me a bottle that was wayyyy to small and also the wrong manifold.
My second bottle was from boostbottleindustries.com. This site is the only reliable site to get an exact size to fit your motor. They shipped me the exact size for my 66cc motor and others have said that they are the only trustworthy site as well.
Once you have the correct size, the performance of low rpm range shows a significant improvement in stability, smoothness, idling, and instant start-ups. No more of this sputtering to life. I'm talking about instant cranking and you hardly have to pedal it to start it.
Well worth the $18 but MAKE SURE YOU GET THE RIGHT VOLUME BOTTLE.
These are so controversial because the websites that people buy them from hardly ever ship the right volume bottle and cause people to think they dont work. I bought mine from a site boostinductionsystems.com and they sent me a bottle that was wayyyy to small and also the wrong manifold.
My second bottle was from boostbottleindustries.com. This site is the only reliable site to get an exact size to fit your motor. They shipped me the exact size for my 66cc motor and others have said that they are the only trustworthy site as well.
Once you have the correct size, the performance of low rpm range shows a significant improvement in stability, smoothness, idling, and instant start-ups. No more of this sputtering to life. I'm talking about instant cranking and you hardly have to pedal it to start it.
Well worth the $18 but MAKE SURE YOU GET THE RIGHT VOLUME BOTTLE.
matching the cc's of the motor to the cc's of the bottle is a must. you can double check the accuracy by using a cc measuring cup and water. a 66 cc motor should have a bottle with the hose that holds 66cc (just make sure you fully dry it out afterwards)
And as DaveC said the intake fitting must be angled towards the cylinder head to have any real effect.
boostinductionsystems.com bottles are made of aluminum
boostbottleindustries.com. bottles are made from pvc
I have bottles from both, i think the first one looks better either way they are good bottles and like i said you can measure and adjust the cc's by adding or removing hose so its really just a matter of what you think looks better
And as DaveC said the intake fitting must be angled towards the cylinder head to have any real effect.
boostinductionsystems.com bottles are made of aluminum
boostbottleindustries.com. bottles are made from pvc
I have bottles from both, i think the first one looks better either way they are good bottles and like i said you can measure and adjust the cc's by adding or removing hose so its really just a matter of what you think looks better
Although this thread was started in January, Ill post for others asking about "Boost" bottles. After making my first one as a experiment, and testing, I make them for all my builds. As far as "Boost" for these engines I see NO boosting in power (although I wasn't concerned with with power), but what I did notice was a smother idle. After installing it we (on the original install) had to turn out the idle screw as the idle was much too high. Yes matching the cc of the bottle to the engine is a must, and insert the fitting on the intake at both a angle and with none in the intake itself (I ground it off on a grinder at a angle). After I fit the fitting to where I want it, I used the dreaded JB Weld (not many uses on these engines) around the threads. Here is a picture of my boost bottle I make out of PVC.
....
Using SCH40 PVC makes for a longer tube as the SCH20 will be short. The picture (getting ready to paint) is that of a SCH40. Each cap holds 5cc (total 10cc) and the tube itself holds the remaining 55.5 cc or what ever the cc of the engine is minus 10cc. I use 1/8" X 1/4' NPT fitting on the intake and a 1/4" X 1/4" NPT on the bottle. Why the two... the 1/4" is easy to find whereas the 1/8" are harder to find, and you really need the 1/8" on the intake due to lack of space.
....
Using SCH40 PVC makes for a longer tube as the SCH20 will be short. The picture (getting ready to paint) is that of a SCH40. Each cap holds 5cc (total 10cc) and the tube itself holds the remaining 55.5 cc or what ever the cc of the engine is minus 10cc. I use 1/8" X 1/4' NPT fitting on the intake and a 1/4" X 1/4" NPT on the bottle. Why the two... the 1/4" is easy to find whereas the 1/8" are harder to find, and you really need the 1/8" on the intake due to lack of space.
Last edited:
I ran a home-made PVC boost bottle for awhile and saw a small increase in midrange torque. Definitely ran smoother, too.
No offense but TBH, given the results found by even those that advocate them, a "subtle" effect on idle and maybe a small increase in performance (& that's debated even here)... I gotta say I suspect the only reason to actually buy one would be for the "bling" factor...
I've still yet to see any professional race machines w/such - which has gotta make ya wonder. If I'm wrong and you've pics/links of an actual pro class race team that uses them, please do post about it
I've still yet to see any professional race machines w/such - which has gotta make ya wonder. If I'm wrong and you've pics/links of an actual pro class race team that uses them, please do post about it
Barely, there's plenty of 2-stroke motorcycles with airboxes that match their engine's displacement.
Take a closer look.
Take a closer look.
I personally think that boost bottles are bull****. Just take a look at the best 2-stroke engines (Highest cc/HP) on the market in the 70cc or so range and you'll notice that none comes with boost bottles. These engines are found on tuned scooters:
MWS 2F4R NX Zip 25pk run - YouTube
This engine is an 80cc 2-stroke producing 25HP and as you can see, it has no boost bottle, in fact it has a racing air-filter.
MWS 2F4R NX Zip 25pk run - YouTube
This engine is an 80cc 2-stroke producing 25HP and as you can see, it has no boost bottle, in fact it has a racing air-filter.
'Tuned" scooters are typically tuned for high-end output at the expense of mid-range torque, too.
You're right, though, scooters have CVT transmissions. My scooter engages it's clutch at 7000rpm, keeps the engine at 9000rpm until the transmission is completely deployed and then revs until 13000rpm. That makes it useless to have any low-end or mid-range power. This scooter with this "2Fast4Race" engine probably tops at 15000rpm. I highly DO NOT recommend anyone to use these engines on bicycles as even on the scooters they can be too powerful for the brakes, frames, suspensions, etc.
That's a large difference compared to a chinagirl with a boost bottle. I put my home-made PVC boost bottle on a 66cc Dax 2-stroke that had a 34T rear wheel sprocket. Most of the time I ran between 20 and 30MPH and I did notice some gain in acceleration in that range. That's 3500-5500RPM with that gear. I never liked to rev those engines over 6K.
My engine ran a little smoother, had noticeably more power when getting on the throttle, and was slightly harder to start. It climbed hills 2-3MPH faster than it used to. The a/f mixture didn't seem to change, was always slightly rich, but I did have to readjust my idle.
Buying a boost bottle aint worth it, IMHO. But they are easy to make, mine cost me under $5. You might not be missing anything without one, but don't write them off as a sham if you spend most your time in the engine's midrange.
My engine ran a little smoother, had noticeably more power when getting on the throttle, and was slightly harder to start. It climbed hills 2-3MPH faster than it used to. The a/f mixture didn't seem to change, was always slightly rich, but I did have to readjust my idle.
Buying a boost bottle aint worth it, IMHO. But they are easy to make, mine cost me under $5. You might not be missing anything without one, but don't write them off as a sham if you spend most your time in the engine's midrange.
I do believe you're better off buying an expansion chamber exhaust (which provides mechanical supercharging) which is suited to your engine displacement, RPM range you desire to boost, ports, etc. Expansion pipes are an art in 2-stroke tuning ^^.
That's the thing: boost bottles tend to have the most results when used in conjunction with an expansion chamber.
