Quieting Down A China Girl Motorized Bicycle???

Catfisher · Apr 5, 2013

Hi Guys,

Lack of funds is going to force me to build a China Girl, as opposed to the geared 4 stroke or electric I want to build. In order to get to work I will have to drive through Peoria Heights; a village connected to Peoria. The police in the village are known to be aggressive toward anything they don't want in the village, including motorized bicycles.

I absolutely cannot risk a ticket as I am unlicensed due to a past DUI. Some of you may remember that I asked the Municipal Court Judge and the State's Attorney to tell me if I could truly ride as the Illinois law is written. Illinois removed the license requirement a year or two ago. The Judge and State's Attorney refused to tell me I could safely ride. The response was "If you get the ticket, then we will tell you." Total BS.

What I need to know is this:

Is there any aftermarket muffler that will drastically reduce the volume of a China Girl engine?

I don't mind if I lose some efficiency, but I need the bike to run well on a daily basis. The trip is about 5 miles each way. I want to be as un-noticeable as possible.

Thank you for all replies.

.flg.

donphantasmo · Apr 5, 2013

Re: Quieting Down A China Girl ???

Hmmm. I am interested in the answer, as well. I too would like to quiet my motor a bit.

I hope it works out for you.

JustAnotherBozoOnABike · Apr 5, 2013

Re: Quieting Down A China Girl ???

yeah man, i'd strongly suggest you print out a copy of the pertinent laws, and highlight the parts pertaining to the lack of license requirements, and then carry that with you wherever you go.

...chances are when a cop sees the law in print (he can also look it up if he wants to put his donut down) he won't bother writing a ticket and if he's a real dick and writes it anyway, you'll beat the ticket in court.

peace

, bozo

2door · Apr 5, 2013

Re: Quieting Down A China Girl ???

I don't know about your fabrication/welding skills but a long pipe with the stock, kit muffler out at the end makes for a pretty quiet exhaust with little to no performance loss. 3/4" EMT (thin wall electrical conduit) can be bent and welded to make a pipe that clears pedals and frame.

Cut the muffler off of the pipe leaving about an inch to weld to and use the kit exhaust flange and header pipe as a starting point for the EMT pipe.
You'll need a conduit bender and access to a welder, preferably MIG (wire feed) or better yet a TIG machine.

Also keep your speed down when passing through that area where you're concerned about the police. A China Girl running at half throttle is not a loud little engine with the stock muffler.
Good luck.

Tom

ProDigit · Apr 5, 2013

Re: Quieting Down A China Girl ???

I was thinking about 2 stroke scooter exhausts.
I also am interested in reducing the noise.
The problem is 2 strokes are generally louder than 4 strokes;

I wonder what would happen if you'd put a 4 stroke exhaust muffler on it?
Generally, the larger the muffler, the better the sound damping is.

Dan · Apr 6, 2013

Re: Quieting Down A China Girl ???

2door said:
I don't know about your fabrication/welding skills but a long pipe with the stock, kit muffler out at the end makes for a pretty quiet exhaust with little to no performance loss. 3/4" EMT (thin wall electrical conduit) can be bent and welded to make a pipe that clears pedals and frame.

Cut the muffler off of the pipe leaving about an inch to weld to and use the kit exhaust flange and header pipe as a starting point for the EMT pipe.
You'll need a conduit bender and access to a welder, preferably MIG (wire feed) or better yet a TIG machine.

Also keep your speed down when passing through that area where you're concerned about the police. A China Girl running at half throttle is not a loud little engine with the stock muffler.
Good luck.

Tom

Tom, been meaning to ask you and wanting to try just that, except just use heat resistant flex hose. (can't remember the right word) Then just hose clamp both ends. My thinking is the rubber (like my muffler) will greatly deaden the "echoing" factor. My concern is the nipple left on the muffler side that the hose will fit over, will cause a slight bottle neck even though the exhaust has cooled and now has less volume.

http://www.teleflexmarine.com/products/hose/engine-hose/

LOL, just remembered a few yrs back when I tried it with radiator hose and your reaction........

577-Jersey · Apr 6, 2013

Re: Quieting Down A China Girl ???

I could not believe how quiet my first china girl engine was,,very surprised,,will have to take a look into the stock muffler one day,,bet there is a spark arrester in there thats gonna get clogged up sooner or later also.I found most of the noise comes from the motor itself,,the exhaust is very quiet.

Mr. Minecraft · Apr 6, 2013

Re: Quieting Down A China Girl ???

I know you probably don't want this response, but why not just get a decent bicycle and bike to your destination? If its only 10 miles round trip, that's not bad at all.

If you must use a motorbike, then I suggest the same thing as Bozo; print out the laws and ride courteously. If they still stop you and somehow manage to ticket you, then it will never stand in court.

Trey · Apr 6, 2013

Re: Quieting Down A China Girl ???

My 4 stroke isn't very loud, and the videos I'v seen on the 2 strokes don't seem terrible. I've looked into this a bit, and I'm convinced that 2doors suggestion is you solution. Let us know what you work out.

Dan, I'm pretty sure you already have the most awesome muffler set up ever!
rotfl

I've also been considering a (metal) hose type exhaust. Most likely I'll end up with something made out of 3/4" EMT though...

Nashville Kat · Apr 6, 2013

Re: Quieting Down A China Girl ???

Cousins Cousins-
the dick will soon be gone off fighting hordes of little yellow men swarming all over him on motorized bicycles.

Mike B · Apr 6, 2013

Re: Quieting Down A China Girl ???

Try this;

http://motorbicycling.com/showthread.php?t=34834

Catfisher · Apr 6, 2013

Re: Quieting Down A China Girl ???

Thanks for the responses.

I'm almost 61 and my arthritis plus steep hills are too much for me to do daily. I'm fine on flat terrain and low grades, but we have some steep hills I end up walking up parts.

I have no welding skills, but the reference from Mike B looks really good.

Mike B said:
Try this;

http://motorbicycling.com/showthread.php?t=34834

Thanks guys.

.flg.

Dan · Apr 6, 2013

Re: Quieting Down A China Girl ???

Catfisher, the thing about our little 2 strokes really is not that they are all that loud, especially at their cruising speed of around 22 MPH. (out of the box and unenhanced) But the sound of a weed-whacker, 2 stroke does kind of draw attention more the the sound of 4 stroke lawn mower sound that is for some reason more soothing.

Have a kid in town who is way under driving age and he does about 15 MPH riding around on his China Girl and I might be hyper sensitive to the sound but dang sure know when he rides by the house.

Just thinking the printing out the law thing is a really great idea if even for your own peace

of mind Buddy.

maniac57 · Apr 6, 2013

Re: Quieting Down A China Girl ???

The hose will help noise quite a lot. I'd be sure to secure it to the muffler very well and I bet you can accomplish your goal.

577-Jersey · Apr 6, 2013

Re: Quieting Down A China Girl ???

Hey Catfisher,,my welding skills where bare bones,,
I got one of those cheap $100 flux core,wire feed welders(90 amp 110v.)from HF and I love it,,just replace the junk wire with Hobart,or Lincoln 0.30 from home depot/lowes and you will love it,,perfect for working on these little bike kits.Get the extra warranty so you can bring it back if need be.Its good for 90 days otherwise,,mine works flawless,,lays down a really nice bead,,ive welded up to 1/4" and it is sweet!

Check it out in action.
http://www.youtube.com/watch?v=IkDF9dIxHl0

Take care!

Tom

ProDigit · Apr 7, 2013

Re: Quieting Down A China Girl ???

I'd pick up on the idea of trying to mount a rubber hose on the exhaust pipe.
If you're lucky, after the muffler, the exhaust gasses have cooled down enough for the rubber to remain alive.

Master-shake · Apr 7, 2013

Re: Quieting Down A China Girl ???

I was thinking about getting a wide heat resistant tube, cutting the muffler in two and strething the muffler to the rear of the bike, something like an expansion tube but filled with something to baffle the sound and add backpressure.

Also, I read about that guy greasing up the gears to get them quiter so I might try that.

Another guy said something about "beefing up" the head case to make it less noisy, but I have no idea what route to go that would be able to handle that. Maybe thick heat resistant aluminum tape? Maybe a bunch of HR epoxy/putty?

An important question I don't think that has been adressed yet is just how hot the "china girl" gets. It may have a lot to do with a lot of things, but out of the box, how hot it "should" get as a good base line then work from there when thinking about sound supressing.

I'm going to attampt to add more rubber to my engine mounts (the downtube mount in particular and see if that helps noise at all.

2door · Apr 7, 2013

Re: Quieting Down A China Girl ???

Master-shake said:
I'm going to attampt to add more rubber to my engine mounts (the downtube mount in particular and see if that helps noise at all.

Our advice? Get rid of any rubber in your engine mounts. You are not eliminating vibrations but only transfering them to the mounts and the fasteners. Eventually something is going to fail. The engine should be mounted solid to the rame. No rubber or resilient material.

Tom

Master-shake · Apr 7, 2013

Re: Quieting Down A China Girl ???

I'm chasing another idea now. That rubber thing was going to take too long. I noticed people talking about boost bottles helping low end power, I'm going to look into making one, because If i can be cruising at low speeds and not have the "Jerkiness" then there won't be a need to go faster, because as it sits the only real reason i go fast is so the engine runs smoothly i can't get it to run smoothly at low speeds. Lower speed less noise =)

Master-shake · Apr 8, 2013

Re: Quieting Down A China Girl ???

I got a pretty good link for a rubber exhaust hose to extend the muffler all the way tro9 the back of the bike. all you need past this is heavy duty rubber clamps.

-Rubber Hose Specs-
Construction: Black synthetic rubber with wire helix and HD synthetic cord
Burst Strength: 870psi
Temperature Range: –20° to 200°

I wonder if that china girl gets hotter than this?

http://www.westmarine.com/webapp/wc...&subdeptNum=50650&classNum=50651#.UWJD4qLvt8E

I wonder if I can fill it with some sort of baffle the entire length of the tube. would fiberglass insulation work? I'm wondering.

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