how to make an engine quieter/stealth

I have messed around with a remote air intake, and it does make quite a difference in sound, and I have not seen any loss in power, plus it can be experimented with without a welder or fancy equipment, what ever is lying around the garage, an old vacumm hose, a paintcan top, heck I even used an empty soda bottle, work great.
 
On the subject of modifying the intake, has anyone added any type of scoop or funnel that would catch air instead of the little holes that have to suck air that's already going the other way??
 
This pipe works well, and the muffler's half again as long as kit muffler- doesn't seem to cut power.

but I had to cut it to run under the bottom bracket-- then joined with worm clamps and can aluminum- turn the aluminum around to blend in better- chrome tape gets dark

the pipe runs about $35 before shippping.
 

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a question reguarding the mouse pad on the clutch cover to reduce noise, is this on the outside or the inside of the cover, and if its on the inside will it fit???and what are some examples of good things people have used to stuff a bit of in between the fins?
 
Outside. Silicone rubber was used to glue the pad on.

The new dampener material at Sick Bike Parts and others works amazingly good. Pads for clutch, magneto and clutch cam cover. It's a highly viscous material that sticks and dampens vibrations. It has a heavy mylar backing. All you do is peel the paper backing off and stick it on the cleaned interior surfaces. This works good. Tap a cover and it just sounds dead, no metallic sound.

I used small chunks of the silicone hose that comes with a SBP expansion chamber to stuff between the fins. The silicone rubber is very heat resistant which is why SBP uses it for their expansion chambers. I have their expansion chamber and got the add-on muffler, makes the bike reeeal quiet..shft.
 
If you ain't that bothered, perhaps others in England won't be pleased terribly.

I'm also going to try the sound dampers at Sick bikes- but my bike makes less noise than a leaf blower or most lawn mowers- and it's here and gone- not roaring in one place for very long-

I usually shut down at lights- just to cool thye motor and save a little motre gas.
 
Wow you guys think the SBP expansion chamber makes the bike quieter, heh my experience would be it is 20% louder .....15 with the "silencer" on.
I should test it out but i found a 1/8 scale rc car silicon, exhaust outlet made more of a difference than the "silencer".
Maybe if i am feeling better tomorrow I will dig out the DB meter and see what is what.
 
Well after looking at my exhaust, it would seem that its time for more of the silicon tubing from SBP, the old stuff is cracked and what not. Now I would just order it, but due to the cost of shipping I think im going to try some different options. The connector pieces are all copper , has anyone tried to solder them together, I know the exhaust mani gets hot , but hot enough to melt the solder?
 
muddybike said:
Well after looking at my exhaust, it would seem that its time for more of the silicon tubing from SBP, the old stuff is cracked and what not. Now I would just order it, but due to the cost of shipping I think im going to try some different options. The connector pieces are all copper , has anyone tried to solder them together, I know the exhaust mani gets hot , but hot enough to melt the solder?
Click to expand...

To answer your question. Yes I have done that and it was an epic failure. I soldered a crack I had in my old exhaust pipe ( smacked the muffler somehow) where the weld broke. The thing was fine for all of three minutes. Solder melted right off. However, I have used "quick steel" on old car exhausts before and it worked fine. You can get some from any local auto parts shop.

MSR Racing Quick Steel Epoxy Putty - Dirt Bike Motocross - Motorcycle Superstore
 
I copied from a friend Kip Harley in Maine and cut my black muffler about 2" from the curve out of the engine and attached the two ends together with a 7/8" ID plumbing 3/4" flexible water connection. It works well to keep the output law and back out of the way pointing down to the ground. It is a lot quieter. Kip also sells kits to put sound reducing layers under the 3 removable covers on the China engines to help dampen the sound. He also with Pirate Cycles sells a quieter spring chain tightener that reduces noise. I also wear ear muffs and I am like hear no evil no more. Kip can be reached at [email protected]
 
Any suggestions for quieting a 4-stroke? Part of the reason I bought a 4-stroke was because it is quieter than a 2-stroke. But even still I have to ride with earplugs at wide-open throttle.

I extended the pipe to the stock muffler, added a Supertrapp, and wrapped the whole exhaust with fiberglass header-wrap. My goal is to get my bike as quiet as one of those dainty little Vespa scooters. But for all my trouble, it doesn't seem to have improved things much at all.

My best guess it that the whole engine is radiating noise. I've never considered intake noise before. Does that effect 4-stroke engines too? Add to that the whine of the gear box, and I feel like I'm back to square one.

Has anyone ever fabricated a wrap-around enclosure? Something simple like a rectangular sheet of aluminum bent over the top. Maybe I could find a junk computer of about the right size and use the PC case? I imagine it could be lined with some kind of sound proofing (muffler packing?) and left open for airflow and the mechanicals.
 

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It sounds like you've got a few things causing the noise. Something I just heard about today from somebody is lubricant you add to your oil to coat the metal surfaces of your motor. From the reviews I've read online it's a practically a miracle product that reduces noise and improves gas mileage. You should probably make a list of things that could be causing noise and check them individually.

My first thought is your mounting is loose which is causing the high RPM noise. If it's only loud at wide open throttle, it sounds vibrational which more easily fixable. I don't know why the gear housing might whine though.
 
What I mean is that when the engine is at idle, its positively hushed. But because I use a shift kit, any time I'm moving I have the throttle near the high end, and the gearbox is under load. It doesn't seem to make a difference what speed I'm going.

Obviously wind noise makes a racket at 30+MPH, but I can handle that.

I'm also concerned about noise for safety reasons. I used to bicycle commute 100% pedal powered, and I could tell if a car is approaching from behind by just the sound of it. But with the motor going, I've been startled a few times too many. It would be really nice if I could perceive dangers and hazards more like I used to.

God knows I need it.duh.
 
Part of what I appreciate about these bikes over electrics is that the noise helps signal drivers. Hearing for cars is probably not going to be possible with pretty much any engine running. Improvements are always possible though.
 
In my experience, loudness does not make me safer. About a month ago, I was riding down main street, making a racket as usual. Despite this and it being broad daylight, a lady in a minivan looked right through me and pulled out of a driveway right in front of me. It was the first panic stop I've had to make with my motorized bike. The passengers saw me, but not the driver. If I didn't have my wits I would have gone under the bumper.

I just assume they don't notice me...even if they look right at me while my engine is shaking their windows. A quiet bike allows me to hear more, anticipate danger, and stay safer.

High-end scooters are super quiet...how do they do it?
 
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