How does a Boost Bottle work?

Discussion in 'Performance Mods' started by greenevegiebeast, Jul 4, 2008.

  1. Dave C

    Dave C Member

    They do:grin5:. I put one ment for a 125cc dirtbike motor on a KT100 Yamaha gokart motor. It made enough difference they started to show up on the rest of guys I raced against:ack2: Then I moved to SuperKarts with a 250cc Suzuki RM250 watercooled motor. It had Boysen Power Reeds, Mukuni flatslide carb and a Roost Boost bottle. Kart weighed 210, I weighed 230, it would pull the front end up going from 2nd to 3rd...on dirt:devilish:

    I do think that the shorter the intake is the more you can use one and if you run mid-to-top RPM's. A expansion chamber is a must. It's part of a balanced system.
    Last edited: Jan 9, 2011

  2. HeadSmess

    HeadSmess Well-Known Member

    blah blah blah blah.

    a lil bottle from ebay will do nothing.

    so no, boost bottles dont work.

    but, then again. a tuned pipe is a resonant system. inlet manifold length is a resonant system.

    the BS is the bit about "double rich mixture" etc. what a load!!!!

    its about tuning. resonance. the bottle replaces the length of inlet pipe you cant have in a confined space.... this reduces the "effort" required to draw in the next charge of air/fuel.... here we go into port orifice area and distance and bottle capacity and rpm of motor and valve/port timing-overlaps, volumetric efficiency i could fill two pages with a list if needed...

    i wouldnt buy one.

    engine design is much like making a jug that can pour water. some designs work, some dont. but you still paid for the thing....
  3. happycheapskate

    happycheapskate Active Member

    I paypalled a member for one, and promised to make a video.

    I agree, the idea holds water, but possibly many of these kits are ineffective. I figure I will try it, and if not, sell it at cost I paid for someone else who wishes to try it.

    I thought the idea was to prevent fuel blowback out the carb & filter into the air at more "extreme" tunings and full throttle running.
  4. DuctTapedGoat

    DuctTapedGoat Active Member

    But seriously, how much of that blown back vapor is going in that tiny tube? There's also no opening on the other side of the bottle, so it's not really going in there... it's snake oil.

    But! The concept holds water, yes. You'd need a directional valve on your intake port and on the inside of your air filter. Then get a hose that will take vapor from that "chamber" between the directional valves and have it feed back in past the air filter.

    That's the only way I see that concept holding any merit whatsoever.

    Or you can just go reed style at the intake mani and just NOT HAVE blowback in the first place...
  5. happycheapskate

    happycheapskate Active Member

    Why would the bottle need 2 openings? The first few seconds of running would create engine vaccuum. It seems the bottle should operate in a state of vaccuum with a fluctuating level of vaccuum, and if anything, it probably helps atomize the fuel.

    I have not seen any reed type intake parts available for happytimes. Do you have one, or did you make one?

    I think its quite possible that its effective, even on such a small engine.

    Have you ever seen Stirling Engines? They fluctuate a gas between a similar "bottle" or chamber, or a second piston and chamber, and can operate at very high RPM.


    I think one of the best ideas someone had on this board or motorbicycling board was to use a quality rubber hose about 1 foot long and move the carb back. If this doesn't show a noticeable improvement, I would probably try that next.
    Last edited: Jan 19, 2011
  6. DuctTapedGoat

    DuctTapedGoat Active Member

    A vacuum? Seriously?

    It's not a closed system so there's no pressure!

    There has to be pressure to have a vaccum... the SAME amount of unburnt fuel is going to be between the intake and filter, boost bottle or not.

    I haven't done a reed setup, but there's plenty of people who have and are doing them.

    Here, take this test.

    Get some small hose line, such as that which is in the boost kit.

    Get a clear bottle and airtight ducttape it to the opening, so the only way in is through the tube.

    Light a cigarette and blow the smoke right at the tube. Hard slow, soft, short fast, anything.

    Let me know how much smoke you see traveling through the tube and into the bottle. That's how much fuel vapor is going into the boost bottle. Now, if the boost bottle was on the inside of a reed and the pressurized intake mani had nowhere to push the unburnt fuel, yes, it would help because there would be some pressure and a vacuum would be created, but its not that kind of setup, and if it WAS, it wouldn't be 10 bucks.


    If you don't like that test then try this.

    You know the fish tank cleaner/drainer vaccum tube, right?

    It works cause there is an open end on one side. Try putting your thumb over the top end and pumping water out.

    Or this one.

    Drain a gas tank with a garden hose - but don't suck to start the flow. Instead, make an airtight seal between the gas can and the hose. Now, without squeezing the gas can, magically make a vaccum to get any amount of fuel into the tank.

    Last one, I promise.

    Take an eyedropper, and stick it upside down in the dirt.

    Take a 5gallon bucket and dump it as best you can right through the opening. Let me know how much water got inside.
    Last edited: Jan 19, 2011
  7. happycheapskate

    happycheapskate Active Member

    I don't know what you mean about arguing about "closed systems" and using buckets and cigarettes and such.

    I am talking about engine vaccuum. There is a a pulsing engine vacuum present when the engine is running, the same vacuum that draws in fuel from the jet and air through the venturi. There is pressure; atmospheric pressure, outside the bottle and outside the engine.

    Cars and even diesel freight trucks up to the late 70's used to use engine vacuum to operate various systems such as windshield wipers and cruise control. Engine vacuum is still used to operate brake boosters on modern cars.

    While we are doing unrelated and entertaining science experiments, here's one for your next party. (boiled egg drawn into glass bottle.)

    Have a good ride, DTG. The great thing about this hobby is these are mostly home built or assembled, and largely unregulated, so you can enjoy the machine of your choice.
    Last edited: Jan 20, 2011
  8. happycheapskate

    happycheapskate Active Member

    Give Me Vtec has mailed the part as promised, in excellent condition. Thanks GMV. I will try this out later and post results, hopefully video.
  9. sideshowbob

    sideshowbob Member

    I dont know about more power but!!!

    There is a vacume, thats how the fuel gets sucked in from the piston going down. I've seen the vapor fuel/air in a clear boost bottle, try your pop bottle and you will see that unburned fuel/air does fill the bottle but only when you let off the throttle. Rethrottle and the gases get sucked into the combustion chamber. Try the clear bottle experiment you will see the gases. Or try pushing your bike in gear and then tell me there is no pressure/vacume as the motor cycles. They work in principal. Now whether that give you more ummmph, I think its probably there but miniscule. If you were forcing air air/fuel per stroke in you would get more power (bigger intake/carb diameter) Or build a supercharger or turbo to ram more atoms per cycle into the intake. Then you would get more "Power" ; same volume of atoms same power, more atoms, more power. Its volume and density. But hey guys its a tiny motor. I think 2 1/2 to 3 1/2HP from one of these made in your backyard motors is pretty good. If you want a really high quality one I think you would have to machine the whole thing your self from billets and uses good jap/german bearings/bushings. Otherwise its a $75 dollar motor from some backyard chinese factory, probably made of melted beer cans, enjoy it and ride the p*ss out of it until it throws a rod. You could probably make one explode real quick with a supercharger. I can't wait for one of these guys to post a pic of one he built and how it all explodes. yee haww!!!
    Last edited: Jan 25, 2011
  10. DuctTapedGoat

    DuctTapedGoat Active Member

    And that's exactly the point.

    Instead of arguing "They work!" "They don't work..." what we SHOULD be doing is saying "The concept is there, and what concept is there just doesn't show a significant amount of improvement. Is there a way that we can take this boost bottle concept and apply it in a way that will show some considerable improvement without putting a major dent in our wallets?"

    I've always been an advocate against them, but usually when people are asking about them, they're new to the motored bikes, and are looking at "New Air Filter", "Boost Bottle" or "Expansion Chamber", and ask which is better.

    One costs 70 bucks, one 20, the other costs 10. OBVIOUSLY the boost bottle is going to be the bottom of the aftermarket mod barrel.

    But, I know I haven't seen a single person who says they're junk say that the concept isn't there, so lets take the concept and make it worthwhile.
  11. happycheapskate

    happycheapskate Active Member

    EDIT: some of the commentators are calling this a "gas box", and some say it has a spring inside.

    Video shows boost "bottle" that is some kind of rubber, telescoping tube.

    Wierd, it looks to be blowing out/increasing in size as the engine revs.

    re: supercharger hahaaha. Some people are using Ford F150 smog pumps on 5hp Briggs 4stroke engines and apparently it works if done well, till you over-rev it and blow the gasket.

    I wouldn't even bother trying to do something like that to a 2hp china bike motor.

    The boost bottle thing is worth fooling around with once though. I figure I could recoup my 15 bucks easily by selling it to someone else who wants to play with it, or just miss out on one night out at Chilis to find out if it worked or not. hahhaaha.

    This video shows an experiment with a boost bottle on a motobecane moped. The film maker says he inflated balloon inside the bottle before closing the lid, then attached it to the running line.
    Last edited: Jan 26, 2011
  12. DuctTapedGoat

    DuctTapedGoat Active Member

    Bam, that's how to do it. I was thinking about springs and large syringes and also balloons. That actually looks like it would serve the purpose the boost bottle claims to! Good find!
  13. technomancer

    technomancer New Member

    So... uh, did you ever install the bottle on your bike?
    if so, what did you think of it..?
    lol i read 3 pages of your posts hoping for personal experience.

    i lean toward a placebo effect on performance.
    but i feel like it could help with idle.

    the engine's not creating enough pressure in the bottle to really force any more air into the cylinder. you can see that from the balloon.
    the longer intake tube seems like its the way to go.
  14. happycheapskate

    happycheapskate Active Member

    I haven't because the bike has been in storage while I have had other obligations.

    Something of interest, the large 32oz bottles of Slime sold at OReilly's have a barb-fitting that works great with the same kind of hose used with the boost bottle intake manifolds. I plan to try the washed-out Slime bottle also, when I get to ride the bike.

    The engine does not create any pressure in the bottles. The engine creates vaccuum, which fluctuates with the engine cycles. The boost bottle is supposed to dampen these and absorb any "blow-back" into the short intake manifold tube, and perhaps help atomize fuel that enters the bottle.
    Last edited: Apr 19, 2011
  15. goodtime65

    goodtime65 Member

    they do work and I will post a vid
  16. Scottybotty

    Scottybotty New Member

    They'll work if you take the time to dial in the carb and ensure no intake/exhaust leaks. New gaskets and soldering the boost bottle fitting in place. Ensure the fitting doesnt protrude inside the intake by filing it smooth to the inside wall. This really isnt a "Bolt On" Mod and I think a lot of people get frustrated and throw it away...... Too bad because the engines run great once set up properly.
  17. adrian101

    adrian101 Member

    how do they work? Well first of all it didn't work for me. I tried everything to tune the carby to it but failed every time. I think it's my engine which is the fail to except such an awesome mod.

    I have mine in my spare parts box collecting dust. I had a stock exhaust when trying to use mine, Now i have a SBP Expansion Chamber so i might pull the Boost bottle out and test it again.
  18. olow

    olow Member

    ok im no real mechanic but a machinist i am i think the part about a longer tube has something about as when i was 16 a guy i knew would always raise his carb up off the intake to gain more speed and rev something about gas /fumes /distance travel
  19. DuctTapedGoat

    DuctTapedGoat Active Member

    The boost bottle is nothing like a carb intake extension - it's a resonating vacuum.

    The important part is that the bottle itself matches the displacement of the piston.
  20. happycheapskate

    happycheapskate Active Member

    Here is my experience with the boost bottle

    I bought the boost bottle kit from another user on this board (thanks, Give Me Vtec!). It is a 50cc bottle, I think. I have not tried filling it with water or something to test it. It came with 1/4" plastic hose, and a smooth aluminum intake tube with a brass fitting already attached. The fit was perfect, and easily replaced the stock intake tube (new gasket of course).
    The brass fitting does not protrude into the air path. The inside was smooth, and the bend near the carb. was much smoother inside than the original piece.

    On the first run, it started easily (still warm engine) and ran weak. I put it back on about 1/4 choke and it ran great. So I parked the bike and moved the c-clip on the carb. fuel metering pin 1 notch, to give it more fuel.

    Technomancer, I have just installed this today, so I have not tried any other bottles, but since I have some leftover 1/4" hose, I suppose I could try other bottles easily. The Slime (16oz) bottle has a barb on the cap that fits the same hose. The NOS Energy Drink bottle could possibly fit the same bottle cap, or I could drill the cap or bottle and fish a lawnmower tire valve (remove the valve core) through it. I think it would look cheesy but little kids would probably love it. If the stickers peeled off it would just be a blue plastic bottle.

    After warming the bike up properly, it ran fine, idled nicely (where before the bottle addition it was choppy), and pulled ok, and ran well at top speed with a lot less "four stroking" when decellerating or reaching and holding a speed. I turned the idle screw out so the bike would die, but it idled smoothly for a little bit, then died smoothly instead of quickly as without the boost tube. (I have been running mine so it will die when throttle is let off, as I use the engine brake effect on hills and when stopping hard. I guess I don't have this now without using the choke lever, but I'm convinced the bottle works, and the bike runs better.) All said and done, I don't think the bike speeds up or tops out much faster if any, but it did idle much more nicely, and can pull at lower RPM without jerking and lurching (great for parade rides). I am happy, for $15. I don't think I'd want to pay more.

    Last edited: Jun 15, 2011