Muffler for 4 stroke engine.

[ibdennyak]

Whisper quiet

In my misspent youth I liked my vehicles loud, but when I became an olefrat, I decided quiet was better. My technique on a bicycle was to keep my mouth shut until I found this place. Some things I've tried that worked were the old Willy's jeep muffler. Kind of bulky and heavy, but they would quiet down a Wisconsin driven welder to where you could hear the arc. Also, I ran across a lot of military mufflers (manufactured by Donaldson) designed for military gensets. Bought like 50 for $2.50 a piece. Used them on everything from a 5.5k coleman genset (tecumseh 10 hp) to a 164 cid continental. Very quiet. Still see them at surplus centers sometimes. Used on the flat 2 and flat four genset engines. About 14 inches by maybe 6 inches. RV has a 3.5k Onan with that type of muffler. Engine makes more noise than the exhaust. Something like that might work where size isn't a huge concern. Another thought would be some of the Honda and Honda knockoff gensets. The newer ones are super quiet and might be adapted fairly easily. Another possibiliry would be the Honda scooter mufflers from the 70's and 80's. I am waiting on one of them, and can leave results of anyone is interested.

Denny

 

[JemmaUK]

Hey,

There is one thing that worries me about all this silent running stuff and thats safety...

The Tanaka I have just gotten running isnt the quietest, although it doesnt sound like a wasp in a bottle as the zenoah does but at least people (with half a brain/ear) can hear me coming and due to the sound of the motor which is unusual... will look to see whats heading their way...

I *could* wander down the local scrappy and get hold of an old Granada muffler or something and end up with something that wouldnt even come up on the SOSUS sonar net... however I would be then riding what is in effect a 200+lb stealth weapon...

There has already been one instance where I almost hit a girl who decided she'd get out of the car right in front of me in the middle of a cycle-lane ... you know full well who would get the blame in that situation - not to mention the guilt of hurting someone else (whether or not there was something I could do). There has been one case recently of a mentally retarded man being charged with 'death by furious and reckless cycling' - the charges were later dropped.. a cyclemotorist would be torn to shreds by the CPS.

I would rather people know that I am there and stay out of my way than walk out in front of me and get hit.

Its partly a self preservation thing as well - if I dont hit someone I dont get hurt myself..

Just a thought

Jemma xx

 

[Hive]

Couple of Thoughts

Harley riders often use the notion that they want you to hear them coming and that is why they use the loud pipes. Truth, it seems, if you don't see the bike, you likely will not hear it, straight pipe or no.

(If you have ever had to lay a bike down, you will know what I mean.) Looking and hearing is not the same as seeing and listening. Apparently the sound is non directional, until they pass, and becomes part of the discussion when communities move to ban the loud pipes, as it has been hereabouts.

I walked some 30 or forty feet from my idling T-3300 and was surprised how quiet it was compared to sitting on it. I daresay others, particularly those in automobiles and trucks, hear nothing or if they do, pay little heed.

Having said that, I still am leaning toward some sort of silicone tube (thank-you Jemma or Mary for silicone tip) and maybe a muffler of sorts, if the tubing does not lower the sound enough for me - it is for my comfort, you see.

As some know, I tried the copper pipe (plumbing) trick and it did not lower the noise and fell off in traffic and bounced about a bit, with no serious results, like bouncing into a car etc.

The silicone does have me thinking. Might try a copper elbow, some 1 inch copper pipe cut to short length and then:

a.) Sliding a holed-out 3/8" copper pipe into the large pipe and

b.) Soldering in place using end caps or something similar, the pipe extending beyond the ends a bit;

c.) Filling the space created with stainless steel-wool.

The "muffler" would be fastened to the GEBE rack leg neatly somehow and connected to the engine exhaust muffler port via the silicone tube and elbow.

Way cheaper than one of the little short pocket bike mufflers at $30 scoots and fun.

If it works, fine; if not, fine! Will learn to live with the 2-cycle buzzing!

Funny! I can dream up all this weird stuff and still cannot figure out how to replace the heater motor/cage fan in my '93 Eurovan. Please, someone shoot me!

 

[Herrmanator8]

this might be kinda off topic...but, do 4-stroke engines need backpressure? because i wondered if because it has a valve to release the gas, unlike the 2 stroke with just needs it to keep fuel in the engine. anyway...if someone could give me a correct answer that woule be great!

thanks, jon

 

[nwguy]

I've read, and also believe, that much of the noise that comes from small engines isn't exhaust noise. A lot of noise comes out of the air intake port to the carburetor, and from the air cooling engine fins resonate loudly. Equally important to quieting the exhaust would be to quiet these two sources. For the fin resonating sound I've heard one strategy is to cut small wedges of rubber from car tires and cram them in between the fins to stop them from resonating. How you'd muffle the air intake to the carburetor is beyond me, but worth attempting.

-Jim
http://www.outsideconnection.com/gallant

 

[Hive]

Heaven

Is where you live, Jim lad, and I wish I was there - forever.

As it is, I am looking at -2 F tomorrow morning. No bike in my future for next few months, just baking bread, cookies, swilling some beer and a few darkroom sessions.

But, dreaming about bike and hot breezes...

You are correct. Two-cycles are inherently noisy. Only way to quell carb noise is with muffled intake cover, which ends up way large to be practical, I am afraid.

The fan on the Tanaka's is another item that cannot be controlled.

The actual exhaust, is a contributor, so am going to play with it, just to do it, really. Have the silicone tubing, and will build the trap (muffler) later in the winter. Will probably be a flop like my last attempt, but need to fool with ideas ...

If there ever was an "Eden," which there was not, it would have been NZ, whenever and now. If I win a lottery, I'll be joinin' ya-all, after I buy off my family!

All the best, in that wonderland you live in!

Slainte!

 

[smitty]

I have built two mufflers now, both for my (so called) 80cc Chinese dream.

Both were attached (one at a time) to a one inch "electrical conduit" exhaust pipe that I made. The first was a "glass pack". That is, a 2-1/2 tube with end caps welded on, with one inch "stubs" (tubes) at each end. The "stubs" extended into the end caps about one inch each. Between these internal stubs was a heavy screen tube wrapped with ceramic wool. (The wool was between the inner screen tube and the outer 2-1/2 inch tube.) It was much quieter than the straight exhaust tube (no muffler), but not as quiet as I would have preferred. The long exhaust tube and glass pack had a nice throaty "pop" to it, and made the little two stroke sound pretty "meaty", but I feared it was too much noise for the general public, and maybe the police, though I was never stopped. The biggest problem with the glass pack, was the fact that oil collected inside of it, saturating the ceramic wool, making it very heavy, and it seemed to reduce the sound deadening capacity.

The second muffler that I made (just today) is based on the stock muffler, with a smaller, drilled, dead end tube, (baffles) at each end of a two inch housing. The exhaust gases must exit through the sides of the front baffle into the housing (chamber) then enter the sides of the rear baffle to escape the muffler, into the atmosphere, to do their global warming thing.

The exceptions to the stock muffler, were based on a modification that I originally made to the stock muffler. After I added extra holes to the baffle in the stock muffler to increase the power, (and the noise), I found that an added tube (3/4 inch) around the second half of the baffle tube reduced the noise and still had the superior breathing (power).

In my home made muffler, I added a middle sized tube, around the rear baffle. The gases now had to enter the end of the middle sized tube, before they could enter the sides of the smallest tube. The idea was to cause the gases to change directions.

This muffler worked very well, but it still had that two stroke zingy sound, so then I added one more baffle in the middle. This baffle is between the two smaller, drilled, dead end tubes. I consists of a large washer, just the size of the inside diameter of the housing, with a 3/4 inch hole in it. Welded to it is a bit of one inch conduit with a dead end, and it too is drilled through it's sides.

So now the gases must enter the front of the muffler going straight, exit the first baffle going sideways, go through the center washer, (straight) out again, sideways, then straight again to enter the tube surrounding the last baffle, sideways again to enter the last baffle, then straight once more to exit the muffler. Yikes! did you follow all that?

This last configuration is the quietest yet, though it still sounds two strokey. (What a surprise.) I may (probably) will continue to experiment.

Oh yeah, all the tubes that I used inside if the muffler (and the conduit exhaust pipe) were of a larger diameter than the stock parts, because I figured the longer length of the exhaust would increase the back pressure.

Sorry I've tried to post pictures several times today, to no avail.

 

[fetor56]

smitty...pics would help a great deal.Possibly your pics are too large and need to be resized but i don't know,i'm only speculating.
I'm sure if u exhaust all your possibilities and fail Mods will be happy to help.

BTW...like that bit "(so called)".......your dream or your worst nightmare.

 

[smitty]

Hey I got one in! Sorry this is the only pic I have in regard to mufflers. It is the stock baffle with my added tube. I drilled several extra holes in both ends of the baffle, later covered the bottom half of the baffle. I split and opened the 3/4 inch tube, then squeezed it closed again with a vice, then tack welded it in place.

 

[smitty]

smitty...pics would help a great deal.Possibly your pics are too large and need to be resized but i don't know,i'm only speculating.
I'm sure if u exhaust all your possibilities and fail Mods will be happy to help.

BTW...like that bit "(so called)".......your dream or your worst nightmare.

I'll open the muffler and take pictures as soon as it's practical, it's been raining a lot here lately.

I don't think it's the size of my pictures, because sometimes they upload o.k., usually they don't.

"Exhaust" my possibilities? Ha ha. Pun intended?