Best expansion chamber

[Member 28982]

I just got a... Pic below and wanna add power... Is an expansion chamber muffler best or is there something else I can do. Already has a performance carb setup... And which rear sprocket teeth is best for top end speed. I have a 7speed. Not afraid of pedaling. Pic on profile. Currently running 49cc with 40 or 44 teeth... Idk... LoL
After I put new engine on bike I will be putting 35 miles a day on it... South Florida weather... Wanna make the 17mile to and from trip only take 45minz not 90.

 

[extremeodd]

If you want something that will bolt on and roughly double your power (not even an exaggeration) get an MZ65
https://www.ebay.com/itm/MOTORIZED-BICYCLE-MZ-65-High-Performance-Pipe-BLACK/283579679386

The difference between that and the stock pipe is literally night and day.
If your unfamiliar with how a 2 stroke works, a proper expansion chamber that is tuned for the engine will have the almost same effect a turbocharger has on a 4 stroke engine. Between approx 6-8k rpm it's tuned to create a reverse pulse that forces normally wasted fuel-air mixture that escapes the combustion chamber back into it which increases the amount of air/fuel that is available to burn compared to a stock pipe.

Avoid the banana style and the zeda88/cdh66 pipes, they either add minimal to no power (banana) or add very little power for the money (zeda88/cdh66)
Zeda88/cdh66 (looks like an mz65 but its far skinnier and the header is all wrong)

Banana pipe (These aren't even a chamber despite how they look, when cut open each end has a tube that extends to the middle where they have a .5in gap. The "chamber" housing is essentially for show)

With sprockets the higher the tooth count the lower the top speed. You can figure out the rough max speed of any sprocket with this calculator:
http://www.diygokarts.com/speed-calculator.html
Simply enter your wheel size, divide engine rpm by 4.1 and enter it (8k rpm is about your max speed which is 1,951 or round up to 2000), enter the sprocket you want to know the speed of in the "teeth on axle" field and enter 10 on the "teeth on clutch" field.

 

[Member 28982]

Question. When I took off end cap off stock muffler. It got louder. Does this increase or decrease power? (I wanna take a reciporcator saw and cut in half)
Is this good for go, speed or opposite? I did notice loudness, and some speed increase or torque on my 49cc. But I need more power...does this decrease up?

 

[FNTPuck]

extremeodd pretty much nailed it. MZ65 is the best "bolt-on" pipe.

Cap off stock pipe helps power some, but a 2stroke needs a chamber for proper scavenging and control of the AF mixture - a properly sized pipe for your motor will not only help make power, but extend your RPM range.

"Best" pipe will depend on your engine. On a stockish city commuter you may be happy with an MZ65 or a smaller dirtbike pipe like a KTM65. A mild ported setup might want a medium pipe like an RM80. A big bore, stroker, or aftermarket topend build like the stihl Frankenstein or an AM6 will want a big top end pipe like the KX85 or the YZ85. It all depends on the motor and the goals...

In this case, the MZ65 will serve you well without the exorbitant cost of a converted dirtbike pipe($170-$200+!)...just make sure its a REAL one and not the zeda/cdh66 knockoff which is much smaller and much worse performance.

 

[extremeodd]

Question. When I took off end cap off stock muffler. It got louder. Does this increase or decrease power? (I wanna take a reciporcator saw and cut in half)
Is this good for go, speed or opposite? I did notice loudness, and some speed increase or torque on my 49cc. But I need more power...does this decrease up?

Some people report an increase in power, some people report losing power when doing that. Personally I drilled several 3/4in holes in the stinger of the cap on my stock pipe but it didn't seem to change anything. If you were to simply cut the stock muffler in half all you'd probably gain is a hell of a lot of exhaust sound and no power gains. As FNTPuck mentioned, 2 strokes need an expansion chamber for the best power.

Otherwise it's sounding like your trying to increase your motors output without spending much money, or trying to find the cheapest power adders and all I could really suggest other than an expansion chamber would be to ensure your intake/exhaust gaskets are port matched (cut out any of it that is blocking the port) and maybe replace your headgasket with a thinner copper one from bicycle motor works to increase your compression a touch.

 

[zean]

Excuse me extremeodd. How does the Sick Bike Parts pipe rate in your rankings of expansion chambers? Thank you.

 

[extremeodd]

It would work and most likely have a higher power output than stock however it doesn't appear to be a well tuned pipe and more of a "one size fits all" deal. For the price, you'd be better off with an MZ65

 

[Member 28982]

It would work and most likely have a higher power output than stock however it doesn't appear to be a well tuned pipe and more of a "one size fits all" deal. For the price, you'd be better off with an MZ65

I'm looking at that but dont want chrome and black model doesnt say expansion chamber.
Can I paint it? Surely with high temp paint? Anyways... Also second question . what are these bore kits for 66cc? Do they turn it into a larger cc?

 

[CrazyDan]

I'm looking at that but dont want chrome and black model doesnt say expansion chamber.
Can I paint it? Surely with high temp paint? Anyways... Also second question . what are these bore kits for 66cc? Do they turn it into a larger cc?

Yes, the big bore kits with iron sleeves made with the proper 66/69cc bolt spacing works great. Unless you do proper port matching, polishing and widening the transfers, you really won't see much increase in hp over a properly tuned 66cc. You will need a larger aftermarket carb (19mm+). A tuned expansion chamber is a must. If you try to run a stock carb and pipe on a big bore kit, with no tuning, have fun.
You seem to be a plug and play guy, with no mindset on tuning. Why not get a 4 stroke and stop trying? I got a 4 stroke for reliability, but have done mods. You need one because you can't seem to wrap your mind around the simplistic complexity of engines, even 2 strokes.

 

[Member 28982]

Yes, the big bore kits with iron sleeves made with the proper 66/69cc bolt spacing works great. Unless you do proper port matching, polishing and widening the transfers, you really won't see much increase in hp over a properly tuned 66cc. You will need a larger aftermarket carb (19mm+). A tuned expansion chamber is a must. If you try to run a stock carb and pipe on a big bore kit, with no tuning, have fun.
You seem to be a plug and play guy, with no mindset on tuning. Why not get a 4 stroke and stop trying? I got a 4 stroke for reliability, but have done mods. You need one because you can't seem to wrap your mind around the simplistic complexity of engines, even 2 strokes.

Yea well I've maintained my 49cc for over 6 thousand miles. I drove it for 120 miles without the small bevel gear screw and none of you can gi v e me an explanation why the bevel gear didn't come out or shift and I tried the gear puller. Wouldn't grab the thread enough to even try so I just put another small gear bolt in it and a new cover. Bevel gear still missing half of one the teeth but. I got this beautiful 66cc today. Waiting on expansion muffler and gonna try a split fire spark plug if they still make em. I am also looking a bore kits and racing cylinder head and. Here the pic... Of course I'll have to you tube the carb set up but should be okay. This Will be my 3rd build. Removing 49cc tomorrow. Pic in avatar photo.