How does a Boost Bottle work?

[Dave C]

They do. 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 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

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.

 

[HeadSmess]

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....

 

[happycheapskate]

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.

 

[DuctTapedGoat]

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...

 

[happycheapskate]

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.

http://upload.wikimedia.org/wikipedia/commons/c/cc/Alpha_Stirling.gif

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.

 

[DuctTapedGoat]

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.

EDITADD:

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.

 

[happycheapskate]

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.

http://www.youtube.com/watch?v=xZdfcRiDs8I (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.

 

[happycheapskate]

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.

 

[sideshowbob]

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!!!

 

[DuctTapedGoat]

I think its probably there but miniscule.

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.