boost bottles

[caps 999]

do they help will it make any difffernce  bike allready has a mugen barrell and vforce kit ive got a answer boost bottle kit here for my 480 i was wondering if anyone know if itll make a differnce

[holeshot buddy]

YES they do work
give the bike more bottom end to midrange
as long as it has the right volume

cheers rusty

[Lozza]

Test it back to back on a dyno and you will soon see. Then take the V-force out and put a stock cage in and see what happens then  Biggest difference will be your wallet will be much lighter.

[holeshot buddy]

so you have tested or ridden bikes with boost bottles lozza

[Lozza]

Yep many times. On tuned and stock engines. Made a slight difference to fuel economy nothing more.

[caps 999]

well there a bike dyno at work so mabye i can give it a shot

[mx250]

I did an experiment on an LC and a DT175 where I clamped off the boost bottle as I rode. I couldn't pick a difference in power. The only difference I noticed was the LC seemed smoother with the BB.

[holeshot buddy]

so the works kawasaki and yamahas were wrong  then
even suzuki tried it
i spoke to brad lackey and he said they were testing the rn500
and he secretly fitted a boost bottle on
his lap times increased by 2 seconds
but the jap technitions found out and made him take it off :'(
i have one fitted to my 540 suzuki and i noticed the difference
and i have ridden 2 yz465 jetted same, same pipe ,and gearing etc
one with boost bottle one without
the one without felt faster lifting front wheel out of corners etc
the one with the bottle was smoother and easier to ride
but was the same speed as the other one even when the riders swapped
remember its not a horsepower gain it slightly changes the spread of power

[All Things 414]

I think a lot of people associate horsepower to laptimes. Especially on motocross bikes. Why do these modern bikes go so much quicker for the average Joe? Because they can "use" the power. The same guys struggle on two-strokes with their all or nothing tendencies. I'm a big fan now of gearing my bikes fairly high for motocross tracks especially if they're slick or greasy. Since I've started doing it my riding has improved 100% and I'm a lot smoother. Especially on these "big bore" bikes that most of us seem to favour. (Got the idea from the manual for my CRF 250. About the only thing good about the whole bike... )
What Rusty's saying makes a lot of sense to me. Not more, just better.

[mx250]

so the works kawasaki and yamahas were wrong  then
even suzuki tried it
i spoke to brad lackey and he said they were testing the rn500
and he secretly fitted a boost bottle on
his lap times increased by 2 seconds
but the jap technitions found out and made him take it off :'(
i have one fitted to my 540 suzuki and i noticed the difference
and i have ridden 2 yz465 jetted same, same pipe ,and gearing etc
one with boost bottle one without
the one without felt faster lifting front wheel out of corners etc
the one with the bottle was smoother and easier to ride
but was the same speed as the other one even when the riders swapped
remember its not a horsepower gain it slightly changes the spread of power

Interesting comments Holey but I hope Brad's lap times decreased 2 seconds .

But its hard to believe that even the anal Japanese would make a rider take off an improvement that picked up 2 seconds a lap simply for a 'not invented here' reason. 2 seconds a lap improvement at any level is incredible.

You'll notice from my experiment I said I noticed it smoothed out the power delivery. I didn't give my conclusion that it is worthwhile for this reason. I didn't find it a marked improvement but it did make the motor easier to take to the max, especially with the LC and especially coming off corners. The BB allowed the throttle brought on earlier and harder but I still doubt that it would make 2 seconds a lap difference. In my experience it would have depended very much on the riders ability and style to maximise the advantage. A bit like Casey and the electronic throttle control gizmo - everyone got it but only Casey and Vale, maybe Jorge and Pedrosa, can get maximum advantage from it.

But to answer the original question; yes it does work. It functions by giving extra volume to the intake and effects  the resonance of the intake airflow to improve the airflow at certain rpm's. 
The volume of the BB to engine capacity has to be matched. There are engineering papers and formulas on the net if someone wants to do a search. I think there is an SAE paper on the subject.

[Lozza]

 From the descriptions given 'smoother' etc etc and dropping lap times on a big bore indicates just the engine is being de-tuned.Which is exactly what happens with MotoGP bikes/ F1 cars what have an ample power are de-tuned. All these type of gimmicks disappeared when ignitions  got much better, power valves appeared.........................
 

[mx250]

But Lozza the answer is still 'yes they do work' - there may now be better ways to address the issues of variable airflow through the vagueies of the torturous paths of two stroke porting but the BB can work especially on old 2t's.

[Mick22]

I have disconnected them on my LC's and YZ490 race bikes that I had... could not tell any difference either way, maybe it makes a difference when viewed on a Dyno but never tried that. But never made enough difference that you could feel

[holeshot buddy]

yep 2 seconds faster doh

still the question remains why did the works bikes run them
those bikes were hand made and very expensive
i couldnt see them putting on a bottle just for looks

spoke to dave (radar )cullen the other day he is an ex gp500 mechanic
from early eighties told him i put a boost bottle on my rn500 replica
he said it was a good idea they used them back then and got good results on
the big bores
biggest difference i notice is it will pull 3rd gear around a corner
easier than it did before the bottle its a 4 speed as well
mainly bottom end to the start of midrange is where you
notice it
and yes power valves was the death of the boost bottle
but yamaha still ran them on the works 250 with trick ignitions and power valves

[BJJ]

My Yz 490L 4 Speed also pulled like a clydesdale down low.  I never stalled it on the track.  (Billjackjane is a Boost Bottle Believer)