The ultimate Huasheng 49cc 4-stroke exhaust!

Discussion in '4-Stroke Engines' started by Max-M, Sep 6, 2012.

  1. Max-M

    Max-M Member

    My bike has the common Huasheng 142F 49cc 4-stroke. I recently replaced the "kit" exhaust that came with the engine. I'm now using a 7/8" ID stainless steel flex pipe purchased from Memory Lane Classics <>.

    I've read on this forum that dynamometer testing by EZ Motorbike showed that replacing the kit exhaust with the flex pipe has been shown to give an 18% increase in horsepower.

    I installed the flex pipe by hacksawing the old exhaust's primary pipe about two inches from the engine, sliding the flex pipe over the remaining nub, and securing the pipe with a hose clamp. I then secured the lower end of the pipe with a special clamp (also purchased from Memory Lane Classics) to the bottom of my EZM Q-Matic transmission, and attached the end tip that came with the flex pipe.

    I fired up the bike, and I was immediately VERY pleased with the deep, gutsy new sound of the Huasheng as it breathed much more freely. Others on this forum have said that it's a sound somewhat like a Harley, and I have to agree! Especially when the bike is first started and is warming up.

    On my first test run with the new exhaust, I was VERY pleased with the gain in horsepower that I experienced. I fully believe that EZM figure of an 18% horsepower gain! The HP gain is very noticeable when starting from a dead stop at a stop sign or stoplight, or when climbing any grade. And the top end for my bike on flats (as revealed by my wireless speedometer) has increased from 31 MPH to 35 MPH. The confidence in traffic that I get from faster-off-the-line starts is a real benefit -- and I look a lot cooler now that I can get up to speed quicker!

    But...this new exhaust is loud. Not terribly loud, but a bit louder than I'm comfortable with. I've seen little kids plugging their ears as I've approached! And, on longer rides (my commute to work, for example), I've used foam ear plugs.

    So I sought out a way to muffle the exhaust somewhat, and the solution was quite simple and inexpensive. I found that a very standard "cigar-type" muffler for small engines is a universal fit (Briggs & Stratton, Tecumseh, Kohler) muffler with a 3/4" male coarse thread. These can be bought from a variety of manufacturers, quite inexpensively. I bought my "Arnold" brand muffler at my local True Value store for about $6.00.

    To attach the muffler to the flex pipe, I found the ideal fitting in True Value's plumbing department. It's the "3/4-inch FPT street adapter" (pictured below). It's copper, and it costs about $8.00. I had to ream the opening in the end of the flex pipe a bit to slide this adapter into it; a pair of closed pliers, pushed into the pipe opening and rotated, works well. It's a tight fit to get the adapter attached, but once it's hose-clamped, it's not going anywhere...ever! The muffler then simply screws into the adapter. So, if for some reason I want to run the bike without the muffler (or if I need to attach a new muffler), it's a simple matter of unscrewing/rescrewing the muffler to the adapter.

    I was somewhat concerned about changing the flow characteristics of my flex pipe exhaust by attaching a muffler. But the muffler is VERY non-restrictive, and the final result has been: no noticeable decrease in horsepower, and an ideal decibel-reduction in the sound of the exhaust. My bike is a bit quieter, but it still has a deep, throaty sound to it.

    If you're running a Huasheng 49cc engine, I highly recommend this exhaust system.



    Attached Files:

  2. The_Aleman

    The_Aleman Active Member

    I did the same thing last year, used the "5-7HP" / "4-8HP" Briggs replacement muffler. Easy to find under $10. Near same tone as straightpipe without as much loud.

    Here's my brother's Q-matic with the flexpipe and muffler the day we both installed ours:

    Here's mine idling on a cold morning:

    I wouldn't say they sound like Harleys, but they don't sound much like lawn care equipment like the engines with box muffler do :D
  3. tom-fishing

    tom-fishing Member

    I'm looking at upgrading my exhaust also and am wondering if you had to open up your carb jet after installing the flex pipe?
  4. Max-M

    Max-M Member

    Nope, Tom: I made no modifications or even adjustments to the carb after installing the flex pipe.
  5. Max-M

    Max-M Member

    Aleman: Those are a couple of nice bikes that you and your bro have!

    I wish I had video capability to capture some stuff like that. I may get one of those little GoPro helmet cams.
  6. The_Aleman

    The_Aleman Active Member

    My carb jet showed a lean condition after I both upgraded the exhaust and installed the SBP air filter. The exhaust alone should be fine, but I recommend doing a plug chop anyway.

    Amazon sells an inexpensive drill kit with free shipping that works very well for drilling jets:

    Thanks Max-M! They're both Nirve Knuckles which have proven to be really solid frames for MaB use.
    My brother's video was taken with an Android phone, mine was taken with a Canon PowerShot A2200. A GoPro would be a phenomenal upgrade over either of those!
  7. brujahboy2004

    brujahboy2004 New Member

    I'm wanting to do this same mod on my rear mounted setup. The only real question I have is: How long should I make the flexpipe once I have it? I've searched around and no one seems to want to disclose that info on any post I've seen (at least a dozen, probably more). I've heard horror stories about people putting certain pipes on, trying to experiment with it, and severely damaging their engine :(
    I really don't even want to THINK about risking something like that. Something that bad is way too much of a headache than what I'm willing to deal with at the current time.
    Did you just attach the pipe as you detailed here (without any length adjustment)? Or did you change the length of said pipe before hand? I need to reroute the exhaust anyway and figured I'd go ahead and do a cheap upgrade while I'm at it, seeing as the flex pipe would be the most convenient. I just want it to run better overall; nothing super specific. I'm pretty new at this and just want everything to go well.

    Many thanks.
  8. Barry

    Barry Member

    Hey Max,
    I too tried out your system but, had one problem. The neigbors who always waived at me going by started waiving with only one finger! So, off came the 5 HP muffler, on went a 3/4 to 1/2 adapter and a 1-2 HP muffler. They are waiving with all five fingers now! Exhast.jpg
  9. JackShaft

    JackShaft New Member

    Copper is easy to work with.
    Solder it or if you have the equipment use # 12 or 14 copper wire and braze-weld it. My exhaust is quiet.

    IMG_0164 [640x480].JPG
    IMG_0170 [640x480].JPG
    IMG_0179 [640x480].JPG
    IMG_0183 [640x480].JPG
  10. dimsdale

    dimsdale New Member

    [video=vimeo;58791251][/video]The Real Ultimate 49 cc Exhaust :bowdown:

    Y'all have the right idea, the length should be about 72" from port to baffle. Pic and vid of my machine gun style exhaust. More pics in Gallery IMG_2525.JPG IMG_2526.JPG
    Last edited: Feb 2, 2013
  11. JackShaft

    JackShaft New Member

    Looks Good. Some day I would like to build a similar type exhaust using 3/4" bendable copper tubing.
  12. astro83ve

    astro83ve New Member

    Hello Max, I write to request some information from you, do you know the width size of the bendable tubing, as I am no in the US and I believe I may have found a seller for this type of tubing but it comes in different widths. I would greatly appreciate your reply. Thanks!
  13. Max-M

    Max-M Member

    Astro: It's 7/8" (inner diameter) stainless steel flex pipe.
  14. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi everyone,

    Looks like some are guessing, and some are trying different solutions.

    First, the length, end, and pipe I.D. are VERY important.
    The Whizzer flex pipe from Memory Lane is too long for the HS 142 motor. The pipe from Memory lane also varies greatly in length and has a major end result if wrong length.

    The Whizzer motor uses a 32.5" long pipe, and the HS 142 requires a different length.

    We DYNO tested pipes for the new generation Whizzer, HS142, Honda GXH50, HF 79 CC and HF 99 CC motors.

    If the pipe is tested with an open end [not tuned tip] it will be loud, and the back pressure will be way off.

    The special 7/8" I.D. pipe is very hard to find and so far only one company in the US makes it. It is used in the medical industry, and can be purchased in regular or S.S.

    When installed with the correct end and correct length the sound is acceptable and isn't very loud. If installed without the special tip and incorrect length it can get very loud. How important is the correct pipe? During testing we found some pipes reduce the power and RPMs, and some greatly improve the motors output. We found as much difference as 10 MPH over-all. The current test motor [99 CC HF] maxed at 41 MPH with stock ratios, and increased to 49 MPH by simply tuning the exhaust system.

    The stock main jet is just right for the correctly tuned flex pipe system on the HS 142 motor, however the Honda motor will need the jet up-sized to avoid a lean condition on top end.

    EZM stocks and supplies hundreds of owners with the correct tuned exhaust systems for the various motors when needed.

    The correct length with the correct tip is 28.5" on the HS and Honda motors. If you install a muffler or remove the correct tip, the length will not be correct, as it has to due with exhaust pulses.

    Have fun,
    breaksalltherules likes this.