Trying to make my 4 cycle 50cc 2.5 hp Honda engine more quiet.

Discussion in '4-Stroke Engines' started by wheresthepassion, Jul 1, 2009.

  1. wheresthepassion

    wheresthepassion New Member

    Hey guys, just putting up a post in order to seek out some knowledge from you crazy bikers! I have this new engine, a honda 50cc 2.5 hp and I love it. However I bought this motor mainly do to the advertising of how quiet it is. But for me it is not quiet enough. I have googled for awhile now, looking at silencers, mufflers, end caps and etc. But I cannot seem to find anything that is made to fit the pre installed muffler that came with the engine. I really do not want to take away from any of my power, specially speed. But the high pitch buzzing drives me nuts. I could even deal with having something that would change the sound a bit, lower it to a rumble, rather then an annoying buzzing sound. Anyhow, I am mainly seeking to creat a stealth ride. So if anyone has any information or owns one of these engines and has tweeked it out to make it more quiet. I would love to hear any suggestions you might have. Oh yeah, I am a school teacher, I would like to keep the cost under $100.00 if possible.

  2. Honda exhaust

    Hi "Teach" I ran my Honda with the can on it for test purposes, tho that can is unacceptable as a Motor bicycle exhaust system! IF you put a flex-pipe (or curved head pipe) out of the can, or replaced the can with a system, you will find that the best thing for the rider is to put the sound (and contaminants) well behind you not in front.

    Have you done any experimentation? What drive system are you using?

  3. bamabikeguy

    bamabikeguy Active Member

    Can you (or anybody having a similar Honda unit) shoot us a picture or two of the exhaust and the plastic opening in the housing that is around it?

    There was some experimentation with metal conduit (some Canadian even had a conduit inside of another piping, for "double walled" muffling, iirc). Was it Beast up in Vancouver maybe?

    The other items involved were a hole the size of a straight edge screwdriver to fit into, to tighten a really small hose clamp on the outside of the conduit. The inside of the conduit attached to the exhaust with that glue that radio controlled airplane's use.
  4. eastwoodo4

    eastwoodo4 Member

  5. fetor56

    fetor56 Guest

    Post pics of your setup as it is now.
  6. duivendyk

    duivendyk Guest

    I recall that Loquin played around with mufflers based on a Swiss design originally for small planes,so did Kerf I think.Check out their threads&posts,it's worth doing .
  7. Danny3xd

    Danny3xd Member

    What are you using for a tranny? Is the noise maker on my Honda MB and have been looking around.
  8. duivendyk

    duivendyk Guest

    Are you sure it is the exhaust ?,have someone listen with a piece of tubing connected to one ear, plug other ear & try to locate sound source(s).You could be surprised.
  9. Bob the boatbuilder

    Bob the boatbuilder New Member

    You can check out what I did using just copper pipe, I had to fabricate or suffer a burnt rear end(the exhaust points forward and is close, real close. The tip was cut at an angle just to look cool. a pic can be seen either in the gallery or my demographic page. I love this engine, but had to defeat the oil sensor for it to work correctly. Next I am wondering how/whether to mess with the governor or not.
  10. JackShaft

    JackShaft New Member

    My 4 stroke exhaust is 3/4" soldered copper pipe connected to the stock muffler with a 1/2" to 3/4" copper adapter. I had to file down the muffler outlet a little to get the 1/2" copper fitting slide over it.The first 3/4" joint is not soldered. A bracket holds it in place. The pipe has 2 90 degree turns to make it down under the engine mount where it makes a 45 degree turn on the left side then straight back past the rear axle. The pipe does not get hot enough to melt the soldered joints.

    I have thought about connecting a Briggs&Stratton type muffler to the end of the copper tail pipe.

    I attached 3 pictures.

    Attached Files:

  11. Bob the boatbuilder

    Bob the boatbuilder New Member

    You could scuff the copper and use flat black wood stove paint to make it prettier. Is it still to loud with all that length? I would guess that you would loose some power by placing more restriction on the backpressure using another muffler. HP is influenced by restriction both on intake and exhaust.
    Let me know what you think of your engine after a few hundred miles. I'm looking to build a mid engine bike. There are so many choices out there and I'm soured on chineese junk, but am aware that the chineese may have sOme worthy items. A bit of research is going to be necessary
  12. Happy Valley

    Happy Valley Active Member

    In my experience, neither electrical nor silver soldering copper tubing will hold up over time to the heat and vibration.
  13. Danny3xd

    Danny3xd Member

    I have yet to try it on a 50cc, but used electrical conduit and (no kidding) a rubber blow bag. Sounds really cool on the HF 79cc. Cost 10 or 15 bucks with pipe, muffler and fittings. I had put a garden hose splitter on it so I had the the option of a lawn mower muffler and/or the rubber muffler. The threaded pc at the end of the conduit has a set screw.

    The blow bag is $7 at Harbor freight and $20 at home depot.

    I put it on as a joke thinking it would blow up, but turned out to work great and good sound dampener.

    But do like the sound and really funny part, kids and animals seem to as well.
  14. spad4me

    spad4me Member

    Are those the toilet water things..
    Hook a hose to it. Then stuff it down the clogged toilet. Turn water on, run away fast. Toilet will either unclog or spray everywhere.
  15. Danny3xd

    Danny3xd Member

    LOL Spad, ayup. Sure are. Well clogged pipes. Never tried one in a toilet. Bet that could make a mess.

    As the bag fills with water from the garden hose, it expands sealing off the sides of the pipe and the hole at the opposite end shoots a jet of water and creates pressure on the clog.
    For our thing it sort of happily pulses. They come in 2 sizes too! (for your plumbing and MBing pleasure)
  16. JackShaft

    JackShaft New Member

    I ended up polishing the copper pipe with some 2000 grit wet sandpaper after filing the excess solder off. It's still some what loud. This setup sure beats the exhaust that came with the engine kit. The price is right with only 4 fittings and a length of pipe from Home Depot. It can also be duplicated by anyone with tubing cutter and small propane torch. It's also easy to repair, replace or modify. Enough vibration can brake anything. I don't have that problem after putting heater hose between the mounts and the frame tubes.
  17. HeadSmess

    HeadSmess Well-Known Member

    mufflers are fun :) you can spend days making one that is actually louder!

    but then again...when you arent workin within the space restrictions required on a small engine... you can do better than the engineeers at honda :ack2:

    the key is... lots of chambers, tuned to attenuate specific frequencies...

    silver solder, a blowtorch, tin cans (aerosols and fruit...) and tin snips. you can do it! its about volume. more volume in the can means less out...
    ha ha. taking liberty with the meaning of volume :) bet yall confused now. do we seperate or separate?
  18. Happy Valley

    Happy Valley Active Member

    Then after you get the exhaust note toned down where you can hear you realize how much noise comes from the intake side.
  19. nwohater

    nwohater New Member

    Last edited: Jun 13, 2011
  20. greguk

    greguk Member

    Taaa Steve - I guess Steve have plenty of free time if he develop bike which have tons of complicated custom made bike parts which wear and tear and can fault any minute.

    But idea of exhaust is right - weld extra pipe to exhaust and do a extra muffler made from can.