Boost Bottle for freestyle?

madscientist

madscientist

chilling with these guys.
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good old p'cola
the more i think about this topic, i can come up with only one option to truly use the bottle properly. drill and tap the bottom of the intake tract on the crank side of the reeds. this will allow the back pressure that is stopped by the reeds to fill and pressurize the bottle then on demand from changes in throttle this will draw on the charged bottle and the extra crankcase volume that it also provides..
 
CARBONX2

CARBONX2

Location
South Africa
madscientist said:
the more i think about this topic, i can come up with only one option to truly use the bottle properly. drill and tap the bottom of the intake tract on the crank side of the reeds. this will allow the back pressure that is stopped by the reeds to fill and pressurize the bottle then on demand from changes in throttle this will draw on the charged bottle and the extra crankcase volume that it also provides..
Click to expand...

You need to read the Y.E.I.S. technical paper to understand why it works. It prevents the double fueling of the air at the specific rpm range
 
madscientist

madscientist

chilling with these guys.
Location
good old p'cola
i know how they work,but i am seeing that by attaching them to the intake manifold you are creating an increase in plenum volume and a cross over chamber. it may still be trapping some of the atomized fuel, but near the volume that would be held / available if it was on the other side of the reeds. theses bottle systems work the best on piston port engines that do not have the reeds stopping the majority of the back flow of the atomized fuel..
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
Boost bottles first appeared on Yamaha dirt bikes back in the 80's, all of those bikes had reed valve engines, not sure why you would ever need one of these on a piston port engine or if it would even work, Honda went so far as to put one on a four stroke XR600 at one point during the Boost bottle craze.
 
madscientist

madscientist

chilling with these guys.
Location
good old p'cola
on the piston port motor the only thing that stops the back wave through the carb is the butterfly, when off throttle the bottle charges and once the throttle is applied it draws the charged mixture in before the new fuel, just an observation of mine that they may just be more effective on the other side of the reeds.on the reed motor how is the bottle getting charged if the back pressure is drastically reduced by the reed assemblies?
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
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What actually prevents backflow on a piston port engine is the piston itself. Two stroke engines are classified by induction types, PISTON PORT is exactly that the piston opens and closes the intake ports, rotary valve same deal, the rotary valve opens and closes the intake ports, reed valve or case reed induction is actually a variant or addition to a piston port engine, same deal except that the reed does not positively open and close the ports completely. The reeds allow easier starting and a much bigger port to be used and allow for easier tuning than a piston port engine, of all the two stroke engine types the rotary valve engine offers the most precise fuel metering and highest horsepower. There are however limits to everything which is why Seadoo stopped the rotary valve engines at 787cc's, anything bigger and crankshaft torsioning would be a problem because of the crankshaft length involved. This is why the 951 is a reed valve engine instead of a rotary valve engine.
 
madscientist

madscientist

chilling with these guys.
Location
good old p'cola
Boost Bottle Theory





Boost Bottle theory is that the boost/equalizer /tube/bottle is a passageway between intake manifolds with a fixed volume, usually the CC of one cylinder or larger, a (momentary) storage container for pre-atomized fuel/air mixture. Since the fuel/air mixture is at a high velocity while traveling through the intake manifold, guess what happens when the reeds suddenly close? The mixture has inertia and physics would suggest the fuel/air mixture has to dissipate this inertia, through a tube maybe? This inertia (pulse) forces the pre-atomized mixture that’s already in the tube from the previous cycle into the next intake manifold that’s reeds are just opening and ready to receive the fuel/air mixture, this is like a little supercharger to each cycle. This all happens so fast at higher rpm’s that it is most effective at lower and mid-range where you are on/off throttle. It takes venturi velocity to atomize the raw fuel from the main jets. The tube/bottle has a charge of pre-atomized fuel that is instantly ready when you go from off to on throttle. It assists in filling the cylinder for a fraction of a second until the carburetor venturi gets enough velocity to fully atomize the available fuel. The advantage is that it brings up the torque and horsepower sooner in the bottom of the rpm range. These have been Dyno tested and proven to work, they show 10hp low end, 4hp at mid rpm, and a 2 hp increase on top end.

From the Original "Hammer"

Totallyamaha is not responsible for any damages that these modifications may cause to your vehicle; any modifications are your responsibility if you choose to do so. We are providing information ONLY. Some of these modifications may VOID your warranty and that is your responsibility to look into. The Totallyamaha users have passed along most of the information found on this site. If you have any questions or concerns about anything on this site talk to your dealer before using any of the information. Totallyamaha will not be liable for any damages or personal injury from any modification performed from this site.
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
The point is fairly mute as the last piston port engines for watercraft were made in 1990 and were 550cc's. What you are missing here is there is an amount of reversion or standoff that occurs even on reed valve engines, the boost bottle give this reversion a place to go or volume to occupy, high pressure rushes to low pressure which is why when the reed valves open again the boost bottle empties. This does two thing it cleans up some of the reversion which makes the intake signal cleaner and adds a slight boost effect to the intake charge.
 
CARBONX2

CARBONX2

Location
South Africa
If you add them to crankcase the volume will go up which will help bottom-end but hurt top-end as crankcase volume is being increased, slowing down the flow of charge through the transfers into cylinder. You will still have reversion at reeds as they do not close instantly. Boostbottles don't have to connect both cylinders, running them individual retains signal clarity at high rpm(jetting shouldn't change). Having them connect to both cylinders spreads the rpm range at which they work but affects high rpm WOT runs(generally need to increase main jet)

Correct carb sizing is also a major thing, too many people think bigger is better. Big carbs give over-rev while hurting low rpm mixtures. A 48mm carb(at butterfly) is equal to a 44mm flow area when you deduct for shaft and butterfly(you want the venturi area to be equal or less than area at butterfly for efficient signal delivery to fuel circuit). If you do the calcs for flow areas for carbs from Jennings, etc:
D= K√CxN
D= Diameter of carb
K= Arithmetic constant depending on use of engine. 0.6 - 0.9, 0.6 = enduro 0.9 = roadrace
C= Cylinder displacement
N= RPM at peak HP
Our motors, if you look at BMEP, put the constant in the middle range so +-0.75
SuperJet at 6500rpm:
=0.8√.350x6500
=38.15mm
If you had a 701 used for longhaul racing with peak hp at 7100rpm, you would use a constant of about 0.9 =44.86mm
SXR at 6500rpm with K=.8:
=40.27mm
1000cc freestyle at 6500rpm:
=0.8√.500x6500
=45.6mm (Thus 48-50mm carbs will work well, thus Ed makes the Full Spectrums 49mm's)
A 44mm annular discharge carb will have +-40mm venturi. You can see why Art specs 44mm(at butterfly) for freestyle on stock bore engines and larger carbs for larger motors
 
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Melmack

Melmack

(Timothy)
Location
New Braunfels, TX
My 300sx has a boost bottle. I'm going to try it with and without. It will take 30 seconds to change from boost bottle to capped off. I'll get a good comparison and report back.

CARBONX2: What carb size would you suggest for a 300 then? I think its actually aground 325cc.
 
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CARBONX2

CARBONX2

Location
South Africa
Melmack said:
My 300sx has a boost bottle. I'm going to try it with and without. It will take 30 seconds to change from boost bottle to capped off. I'll get a good comparison and report back.

CARBONX2: What carb size would you suggest for a 300 then? I think its actually aground 325cc.
Click to expand...
What rpm is peak hp at?
If I work it at 6500rpm it is 35 at venturi, so a 40-42mm
 
Melmack

Melmack

(Timothy)
Location
New Braunfels, TX
They came with a tiny little 30ish round body. I was told to use a 34 from a wr500. Seemed small. Was told by some the 38 would be to big. That didn't make any since to me. Your comments made me wonder. Now I feel the 38 is a good choice. Way bigger than stock but not too big. I got a 38 off an 1100. Should be jetted close.
 
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