Boost bottles

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Easy Rider

Santa Cruz Scooter Works
Jan 15, 2008
2,145
7
38
Nor*Cal
Seems like the veteran's of this board are right on the money when it comes to these boost bottles. I bought one a while ago because of all the hype and found out...NO DIFFERENCE. I only keep it on because I have a big hole in my manifold and I'm too lazy to patch it up. Plus I don't want to spend any $ on these chinese motors anymore.
 

Skyliner70cc

Member
Mar 8, 2008
138
0
16
I installed my boost bottle this morning and took it for a ride.
Here are my findings to date:
1. Engine is harder to start-there are no airleaks in the intake system. Everything is sealed properly.
2. Low to midrange throttle operation is POOR. Idle is erratic and engine stumbles when increasing from idle to higher rpms.
3. At high rpms, full throttle, the engine runs good (same as before). Top speed from same starting point at bottom of hill with speed checked at a point 1 mile past starting point is improved by 0.2 mph. I suspect the 0.2 mph improvement is mainly due to fact that it is 47 deg F outside and the cooler crisp denser air is the reason behind that 0.2mph increase.

4. Next steps:
a. fiddle with needle clip height and see if mixture changes at high speed help.
b. Measure volume of entire setup.
Ok folks, I fiddled some more with it. I got some extra tubing and began trimming it down and checking response on engine. After about 15 1/4-1/2 inch cuts, I found a sweet spot that gave me the following results:

1. NO change in top speed.
2. My low and mid range acceleration is better than stock. It seemed to lean out the overly rich idle and mid-range. I was very surprised by how much acceleration improved over stock. Mind you I am at over 7,000 foot altitude with stock jets that are too rich at my altitude and thinner air.
3. I knew I was tuned to the appropriate total boost bottle volume with appropriate tube length when my idle speed increased significantly and my exhaust note got that buzzy sound of a tuned pipe-its weird I know but it did happen. I had to turn the idle screw a bunch to get the idle back down to normal.

4. NEW OVERALL IMPRESSION: While it did not improve top speed, it greatly improved my low to mid-range carburetor and engine performance. I highly recommend a boost bottle if you are at high altitude with stock jetting. I no longer have low-mid range stumbling and uneven acceleration. I cannot recommend this for someone at sea level as of yet. I am moving in 1 month to sea level and will let you know if it makes a difference at seal level with or without boost bottle. I would have liked more top speed which is the reason I bought it but I'm happy with the results I've gotten.
 

quarkdude

New Member
Apr 22, 2008
15
1
0
Better boost bottle response with re-jetting carb

This one is for you Skyliner70cc ( At least while you are at high altitude )

Quarkdude's instructions on Re-jetting the carb for better boost bottle response and a better running engine: Mainly for the 1800ft above sea level engines and above.

Step 1: Remove carb from engine or if there is room, loosen the clamp
that holds the carb to the intake and rotate the carb to get
access to the float bowl on the bottom of the carb. Rotating
the carb saves you from having to unscrew and disconnect the
throttle cable.

Step 2: This is a good time to close the fuel petcock so that when the
float bowl is removed, the fuel won't be gushing out. Also
it helps to put a rag underneath the carb so any spillage is
captured. Remove the 2 screws holding the float bowl on.
A little bit of fuel in the float bowl may be present. Remove
the float bowl, there is a gasket on top of the float bowl, be
sure to save it for reassembly. There will be a white plastic
round float inside that can be set aside. Now the brass jet
that we want to modify is exposed. It has a hex head on it
to put a small box end wrench or equivelant on to remove it.
Take the jet out. The one I have screws into anothe brass
piece, so I seperated the two pieces and took the jet itself
to the soldering iron.

Step 3: Here you can take a pair of needle nose vise grips and clamp
the jet in the jaws lightly to hold it while it is being soldered
( gets pretty hot ). Use at least a 60 watt soldering iron to
have enough heat to heat up the brass jet. Use 99% pure
silver solder to melt into the middle of the jet to close up the
hole. Use lots of flux to help transfer the heat of the soldering
iron to the brass so that the solder flows nicely into the middle
of the jet and seals it off completely. Check underneath the jet
to see if the solder has filled it all the way thru. If you get too
much solder, just lift the needle nose vise grips and lightly
bang it to the work surface while the solder it molten to
remove any excess solder. Now let the brass jet cool for at
least 10 to 15 minutes before touching it - Very very hot before
that. Now that the jet is cool, it is time to drill it to the size that
will work with your setup. I find that starting a little small on
the drill size helps to narrow down the mystery of what size
the jet really needs to be for your altitude and perfomance
needs. Start small, reassemble the float and remount or
tighten the carb and try a test ride to see how the bike feels.
Usually if the jet is too lean (which in this case will probably
be the case because we started small ) the bike will either not
go as fast as it did before the mod or it will bog a little. For
long term this would not be what you want, but for testing and
tuning around the block it should be fine. Keep taking the float
off the carb and removing the jet and drilling it up one size
then ride the bike around the block for a test and tune
evaluation. When the bike feels like it has a crisp acceleration
after releasing the cluch and doesn't bog on the top end, then
that is roughly the jetting that will work with your setup. The
idle screw on the side of the carb may need to be adjusted.
Sometimes an adjustment of the needle clip might need to be
done. . I did some research on the web as to what drill size to use for a
50cc pocket bike motor and it was roughly a 0.025 inch drill bit
pretty small. That is actually where I started and stepped the
drill bits up 0.025 then 0.026, 0.027 ( Test and tune between
each one) and then finally 0.028 and this is what worked the
best. The exhaust temperature out of the head at the top of
exhust pipe can be measured using an infrared thermometer.
The hotter the exhaust is getting, the leaner the jetting is
getting.
 
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Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
That's a lotta test and tune for a small performance gain.

I think I'll stick with a bigger/more modern engine if I want a power boost.

BTW quarkdude, what kind of boost bottles do you sell?
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
Skyliner- Thanks for the input, and be sure to give us an update when you repeat the whole proceedure after you move.
 

Skyliner70cc

Member
Mar 8, 2008
138
0
16
Boost, thanks but the info on rejetting was not necessary. I can easily rejet by soldering and redrilling but I don't want to with the hassle of having a move back down to sea level in a month or so.

I'll let everyone know how it works for me at sea level later next month. I suspect I'll need to drill out the main jet.

At altitude, I burn a blend of methanol mixed with gasoline to obtain a mixture that compensates for the higher altitude. For the boost bottle test, I'm using straight gasoline which means that my mixture is fairly rich. When using an alcohol/gasoline blended fuel mixed to the correct mixture, I don't have any idle, low-mid range transition problems. Its only when I use pure gasoline with stock jetting that I do.

The bottle is allowing me to save hassle of blending fuel and use straight gasoline with stock jetting to run well at this altitude. However, there is no change in top speed with boost versus regular gasoline but it does run better.
 
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quarkdude

New Member
Apr 22, 2008
15
1
0
That's a lotta test and tune for a small performance gain.

I think I'll stick with a bigger/more modern engine if I want a power boost.

BTW quarkdude, what kind of boost bottles do you sell?
Hello Bikeguy Joe,
I am using a boost bottle from boost bottle industries. I unfortunately dont sell any parts, just buy em, and tweak em, it's the gearhead in me and my need for speed. ha ha..
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
Alrighty then, I was just curious. Have you tweaked anything else on these bicycle motors for a performance gain?

I'm just from the school of "If you want to go fast, start with something fast."

These bicycle motor kits are fun to tinker with, but I get my jollies at 100++mph.

I like that these things are kinda slow and simple.... ;)
 

stingray13

New Member
May 31, 2009
7
0
0
arkadelphia, AR
quote,"Hello Norman,
New guy here on the forum, but long time motorized bike rider. I just joined the forum a few days ago and have been searching thru pages looking for boost bottle references and here it is.
I have been running a boost bottle on my setup and it works great. I had a couple of other people ride it, that have stock motorized bikes, and they could really tell an increase in power. I got mine from Boost Bottle Industries and they are matched to the 69.x cc that my "80cc" chinese engine volume is at and all I can say it WoW, what a difference. Just sharing my experience of what I have on my bike. I have a youtube video of it here: YouTube - Quarkdude's Boost Bottle Motorized Bike 2008

You can see and hear it run. "

so i need to buy the 66-70cc boost bottle for my "80cc" chinese engine kit which is actually a 66cc engine
 

stingray13

New Member
May 31, 2009
7
0
0
arkadelphia, AR
hey quarkdude, will a 36t sprocket, a boost bottle, and a modified pipe bring my speed up any, and if so how much? by the way i have a "80"cc chinese engine kit that is actually 66cc?.i have already made a longer pipe w/ stock muffler welded at the end, and a different clutch cable? so if so what is the expected speed jump because right now it will hit about 32mph.
 

BarelyAWake

New Member
Jul 21, 2009
7,194
21
0
Maine
I just wanted to mention that few of these mods improve top speed to any significant extent - but you may find they improve acceleration and contribute to a smoother running engine.

32mph for one of these "80s" really isn't bad at all - you've done well! Unfortunately evil math saz that with a doubling of speed the drag quadruples, so wind resistance is your enemy here - anything past 30mph is hard fought for :(

I know right? Maths... I hates them o_O


Having said all that and even knowing the vast majority say the boost bottles have little/no effect - I may still get one as I've run out of lil tinkering mods to do lol
 
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Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
quarkdude was only here long enough to try to sell us all boost bottles....he hasn't posted since this thread, which was last year.
 

Street Asasn

New Member
Oct 8, 2009
20
0
0
Austin, TX
I have installed a dual boost bottle system on my bike from boost induction systems it came with a dual tapped intake. Ill try to find my cam and take pics later.. Anyway their logic with 2 bottles is one takes off the top pressure and one takes off the back pressure (something like that). If you have one boost bottle it splits the bottle 50/50 and so a 66 cc bottle is only working at 33cc/33cc (from what I gathered) Maybe they just wanted to sell more but in all reality I didnt care because the more I can make this thing look like a mad scientists contraption the better. SO my results were pretty significant, it started up about 75% faster and easier, and I did have to turn down my idle speed, so they did do something. Taking off seems be alot quicker.. However I really dont think that I gained that much full throttle speed if any.. I am happy with them though for improved startup, acceleration and looks! Just my two cents