question about bosst bottle

cityevader

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May 11, 2008
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Santa Cruiz, CA
Can't Skyliner70cc hurry up and move to sea level (where I live) to continue his unbiased research?!?!?

It must be very poor form to try to open another thread about boost bottles, and I apologize....yet I'm still typing!

It seems that they tend to NOT increase top-end performance (which I don't care about) but DO help with low-end performance (which I AM interested in). Starting and idle quality are certainly not a priority. I simply want to "broaden the power band". Any improvement under load or RPMs below it's high-rev sweet spot are longed for. I'm considering a 48t vs the current 44t, but don't want to lose top end either.

I was aghast at the plumbing seen with these kits...thread-in nipples?!?! How can they possibly not inhibit air in-flow with that length of pipe thread sticking down into the airstream?!?!? Has anybody done any welding onto these aluminum (I assume) manifolds? Something along the lines of a plumbing sanitary Y fitting welded on, so there is nothing sticking down into the airflow, nor a sharp 90* bend for "boost gas" to try to flow through, but rather a gradual angle for the "pressurized backwave" to go more readily flow into boost bottle than out the air filter?

Aside from quarkdude and Autocycler (no offense please, I already know your stance) does anybody else have positive comments or real world actual measurements of performance? My mental prowess of logical analysis is siding with Bikeguy Joe, but I want more opinions than the 6 or 7 guys that have previously voiced opinions. Specifically regarding sub-sweet-spot-rpm performance.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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Re: Very, very sorry to ask a question about...

Hmmm, no response.

I know people either love 'em or hate 'em. Maybe the low end boost is not what some are looking for and never even realize it's there?

Have you matched the exhaust port/gasket, and cut out some of your baffle? Both help the low end.
 

cityevader

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May 11, 2008
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Re: Very, very sorry to ask a question about...

I did grind out the manifolds to more smoothly flow, as well as the exhaust gasket. But nothing to the exhaust. Where/how much?
 

misteright1_99

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Mar 21, 2008
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Treasure Coast, Florida
Re: Very, very sorry to ask a question about...

I still have mine on cause it looks cool, and dont want to go thru the trouble of soldering the manifold closed. The vendor sent me the wrong manifold, and rather than wait an additional week I soldered in my own nipple in using 5/16 copper. Mine is not aluminium it is chromed steel. I silver soldered the nipple using propane making sure it did not protrude into intake airflow. I have gone out riding with the bottle and have pinched it off to try to see any benefit and cannot see any. I have matched my intake and exhaust ports and that made such a differnece I had to move needle to full rich inside carby. Next will be exhaust mod and hopefully thats it.
My 2 cents worth.....
 

misteright1_99

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Mar 21, 2008
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Treasure Coast, Florida
Re: Very, very sorry to ask a question about...

I did grind out the manifolds to more smoothly flow, as well as the exhaust gasket. But nothing to the exhaust. Where/how much?

Take your muffler/intake off, take a exhaust gasket and put it on engine, then carefully cut out the gasket to match exhaust/ intake port on engine (careful not to get shreds inside engine). When done take the gasket off being careful not to turn it around or turn upside down, then put it against manifold/ muffler and see how much metal needs to be removed. Trace with a marker then just match gasket wit a dremel, which in return matches intake/exhaust. My muffler blocked the exhaust port on the engine by at least 25%, prob 15% blocked on intake...
 

spad4me

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Jan 20, 2008
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Arizona Bullhead
Re: Very, very sorry to ask a question about...

This is heresay only------------------ A boost bottle helps at high altitude with midrange, and acceleration.
NO improvement at sea level.
I dont use one.
I have enough intake leaks as ir is.
Fifty two feet ftom you know where.
Sealevel.
 

cityevader

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May 11, 2008
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Re: Very, very sorry to ask a question about...

Take your muffler/intake off, take a exhaust gasket and put it on engine, then carefully cut out the gasket to match exhaust/ intake port on engine (careful not to get shreds inside engine). When done take the gasket off being careful not to turn it around or turn upside down, then put it against manifold/ muffler and see how much metal needs to be removed. Trace with a marker then just match gasket wit a dremel, which in return matches intake/exhaust. My muffler blocked the exhaust port on the engine by at least 25%, prob 15% blocked on intake...
OOps, I wasn't clear...i already ground out intake/exhaust. Not much change in performance. The where/how much was referring to the muffler baffle.
 

misteright1_99

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Mar 21, 2008
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Treasure Coast, Florida
Re: Very, very sorry to ask a question about...

This is heresay only------------------ A boost bottle helps at high altitude with midrange, and acceleration.
NO improvement at sea level.
I dont use one.
I have enough intake leaks as ir is.
Fifty two feet ftom you know where.
Sealevel.
I have to disagree with the hearsay as I grew up in the early 70s on 2 stroke street and off road MOTORCYCLES and have had excellent improvements with boost bottles, and have always lived at sea level. Now these have been considerably larger displacement from 125cc to 750cc and have been with boost bottles that were made by reputable people, in the racing industry, such as White Brothers. There may be an improvement, but when you are talking about 48cc and you get an improvement how much can it be? As for air leaks installed properly this should not add to any air leaks that you have, and to be honest you shouldnt have any, especially with all the posts available to correct them...
 

paul

Well-Known Member
Dec 23, 2007
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Re: Very, very sorry to ask a question about...

never be sorry for asking questions. it is the reason i started this forum was so we could learn from each other :D
 

MarkTur

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May 23, 2008
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Re: Very, very sorry to ask a question about...

I have a boost bottle on my off-road rc truck...it enhances the low end, not top end. I believe I can see a difference - only in acceleration, but I think it works. I would try one...who's selling them?
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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Re: Very, very sorry to ask a question about...

I've been wondering if maybe the reason boost bottles don't really work on our china engines, is because we don't have "tuned" expansion chamber pipes on them? (like motorcycles & RC cars do) :confused:
 
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misteright1_99

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Mar 21, 2008
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Treasure Coast, Florida
Re: Very, very sorry to ask a question about...

I've been wondering if maybe the reason boost bottles don't really work on our china engines, is because we don't have "tuned" expansion chamber pipes on them? (like motorcycles & RC cars do) :confused:

Thats quite a possibility. Now I think of it I never ran one of my Motorcycles without a expansion chamber(s)..
 

cityevader

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May 11, 2008
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Santa Cruiz, CA
Re: Very, very sorry to ask a question about...

Hmmm, no response.

I know people either love 'em or hate 'em. Maybe the low end boost is not what some are looking for and never even realize it's there?

Have you cut out some of your baffle? help the low end.
I've been trying to search for what I've read before about muffler drilling and other mods to increase performance, but cannot find it.

By the way, can anybody explain how this site's search function works? For example, I've tried to search for "gap" to find a particular post for spark plugs, where the word "gap" is clearly present, and yet NO results are present?

My only experience of these mufflers is from curiosity. Pulled out the tube from the muffler. It had an "upstream and downstream" baffle attached to the tube. I have no idea how it works, and a Wikipedia definition of how mufflers works leads me to believe there is absolutely no scientific background to the design of these Chinese parts, based on the designs of all the other components... I truly doubt they are resonantly tuned to self-cancel sound waves like a car muffler with 100 times the engine displacement which is whisper quiet.....
Where was I anyway? I feel like I was rambling or ranting or both for some reason.....oh yeah, so you drill out what part of the muffler? :)
 

cityevader

New Member
May 11, 2008
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Santa Cruiz, CA
Re: Very, very sorry to ask a question about...

I have gone out riding with the bottle and have pinched it off to try to see any benefit and cannot see any. My 2 cents worth.....
Now we're talking!!!
"Yeah, so I put this part on, and could turn it on and off, so to speak, and couldn't feel a difference".....
What about those of you who swear by these things that have "pinched it on and off" to see if any differece?

I'm wondering if these boost bottles act as sound resonators. On car air induction systems, there are frequently these similar tumors on the air inlets to reduce noise. Perhaps there is a psychological effect of performance based on sound?

I'm really not trying to rip on anybody, especially since I have no opinion or experience whatsoever about these things. But for those who swear by these, could a few people provide definitive numbers which say that, oh, acceleration over a certain distance ended up with higher mph at "x" distance, or mph up a grade before/after.... or whatever, had this measureable result...well, I'd like to hear about that....without a link to the manufacturers website with their own "dyno test results", or without the old "it feels better" response, because if my engine is, say, vibrating less, or spewing fewer obscene noises while doing the same work...chances are I'm gonna say it's "working less to give the same output" or even "giving out more work for the same noise output".
Sorry to rany over this thing i've no connection with...simply trying to cull the minds of all these great motorbikers!
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
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63
up north now
Re: Very, very sorry to ask a question about...

I agree on the psychology of the boost bottle. Most of what the directions tell you to do would enhance the performance of these small engines.

What I'm saying is they may work, but on bigger engines and how much do you wanna spend to get a performance boost you can do for free?

Now, about that baffle.... cut it in half, or remove it and adjust your carb afterwards, you will see a small improvement across the rpm range.