can you explain this? boost bottle truths

I dislike it because it is useless 95% of the time and marketed directly at the newcomers It breaks a new builders heart when it does nothing or causes a massive air leak and kills it due to poor installation.
I have stated that a larger volume intake can sometimes improve low end torque and throttle response. A boost bottle is a gimmick very few new builders understand. I also get annoyed at "race carbs" and ''Made in America" Chinese engine kits.
It is simple to get exactly the same or MUCH better results with two hose clamps and a chunk of hose. I hate seeing newcomers get frustrated and give up from predatory marketing like the boost bottle kits. Waste of money for most newcomers. Spend your cash on a good tuned pipe, gearing, and proper carb jetting.
I maintain most new builders need a boost bottle kit like they need 6 toes.

So? I've seen video of turbocharged two strokes as well.
My statement stands. Tuning the intake tract volume is a viable tuning method.
Boost bottles are a gimmick.

You seem to have a fairly high Idol in your video. If your Idle is set all the way down and you are still turning that many r's, thats nothing more than air leak on purpose. It appears from the looks of the outside of your carb that the boost bottle is not doing that much about blow by either. Please do not take this personally, these are just my observations and could possibly be why so many people do not care for them.

When you are pinching the tube waiting for it to die, about three seconds after you grab the tube is where my motor is idling smoothly. I tune for a Bang, ting,ting Bang,ting,ting idle.

Buy one and see for yourself. On a stock chinagirl, like most newcomers have, it makes very little difference despite inflated marketing claims.

I was talking about your intentional air leak. I did not realize you liked idling that high, it appeared that when you grasped the tube it was merely acting as a choke and was gasping for air not fuel. If your test is correct should you not be able to turn the fuel tank off and have the motor keep running? LOL!

I'm just having fun with you, don't get bent and to each his own.

Dozens. Some worked, some did not. Depends entirely on the engine in question. The difference is that I knew what I was buying and how to tune to get any benefits. Most newcomers do not. They fall for the hype.
One more time:
I think a boost bottle ON A STOCK CHINAGIRL is a waste of money for 95% of first time builders. It would be far more beneficial to spend that cash on a tuned pipe or gearing change.
In some applications, such devices can work quite well. Knowing how it works and how to tune to maximise the effect makes it a modification better left for more experienced tuners IN MY OPINION.
Your results may vary.

I just wanted to add that although I have never tried a boost bottle on any of my china girls I have noticed that when you look at pix of all the fastest china girl builds at the races and here people talking about the mods that they have done to improve power and speed, the boost bottle is one thing that is completely absent and none of them as far as I have seen use them or find any value in using one, now all this said.... I'm not saying that there isn't a benefit from a boost bottle in some applications and on some engines, but it seems that if it was a real power, speed or reliability improvement of the simple rough built china girls the top engine builders and racers would be using them and speaking of the benefits of having them.

I say if you have one on your bike and you like it, by all means keep it and enjoy the benefits you believe you're getting from it, I can say that after watching the video though that he engine does act as if it is running with an air leak when the line is not pinched off, having that line pinched off doesn't restrict air flow into the carb through the air filter, but it acts like it has an increase in air flow when the line is released, if it was a fuel flow increase when the line was released it should bog the engine down from a slight rich run condition I would think..... I'm still thinking on all this, and maybe there is something I'm missing here and just dont understand about what is actually happening, but for the engine to have such a high idle with the carb slide close to being close off is typically a sign of an air leak because adding fuel without adding right amount of air to go with it is like engaging the choke and causing a serious rich condition which will bog an engine down not idle it up.... hmmm....I'm so confused Mr Kotter.....! I wonder how many remembers where this statement came from...LOL

If nothing else the Boost Botle looks cool and makes it look like something extra is going on.... I have no problems with them since I have never tried one, maybe I need to make one and rig it up on a bike just to see for myself what it's all about and I think I will when I have the time, now I'm curious just for the heck of it.

, map

Thunderhead,
I do not intend to argue either but would like you to consider a hypothesis. When you say you need to run more initial idle adjustment when you cap off boost bottle your are opening the the throttle slide allowing more air into your charge.(leaning). With the boost bottle attached and the carb settings the same you turn your idle down.

This is why I was calling your boost bottle an intentional air leak that you are actually tuning for. If you are using the fuel from the tube after the carburetor why wouldn't you need even more air to run proper?

Can you see how you are simply tuning for a leak after the carb? If this does not seem to be clear maybe another member can make it more clear.

Once again I do not intend to ruin your parade or anyway be snotty but would like you to consider this.

A boost bottle is a DIY way to help out a piston ported engine to make a little more power if the volume of the bottle and tubing is matched correctly to the engine, it's a harmonic wave chamber on the intake side which allows a place for the intake charge to go when the piston is blocking the port. Most high performance two stroke engines use boost porting with a reed valve and don't have intake charge reversion, so they don't use a boost bottle. You'll never see a boost bottle on a two stroke racing dirtbike or track superbike, because the reed valve does a better job and allows for longer intake charging duration without reversion. By reducing the reversion of the intake charge, you can avoid four stroking from the overly rich condition caused by the intake charge rushing in and having nowhere to go for a millisecond, and you can jet a little richer, making a bit more power. Boost bottles are a technology that can work, but it needs to be done right, there are websites that can help you calculate the volume you would want to use and specify they type of materials the bottle and hose should be made from which are rigid and resist gasoline. The line and bottle need to be rigid in order to get the best results because the whole concept works on wave harmonics.

I have been meaning to do this but never got around to it. Do a careful and well documented study with and with out a boost bottle on the same engine. Keep track of top speeds, MPG, RPM and temperature/barometric pressure, etc. (weather does have an affect)

I personally think they offer no advantage and would love to be proven wrong. But do think prewarmed air with bits of fuel spit in can only help though.

Really would be interesting to try some day.

Have always thought that for so little investment, why wouldn't mass-produced MCs, scooters and such not use them? Hadn't considered that about reed valves. Thanks 16V.

What jet size are you running on the bike in video?

The higher idle deal is becuase more fuel with air is going in. The boost bottle does not create an air leak when done right. It puts a little more ''air and fuel'' into the equition. These folks that are consumed with the idea a air leak is why it idles higher... If you give a bike a little bit of throttle the idle will always go up a tad.

Yes they do offer a tiny bit of pick up on a china girl. I tried it once myself. A tuned pipe proper intake size, bigger carb etc.. can trump this effect on the china girl.

Manic 57 is right they got me to back in the beginning.
It does so little to improve performance its not worth the money.
For the same amount of money you can have a nice RT carb
and you'll have noticeable increase performance.