Stealth bike--Radiator hose for exhaust

[Dragon]

I'm trying to make a stealth bike, and I read somewhere that one way to silence the exhaust on the dirt bike is to attach a piece of radiator hose to the muffler. Has anyone tried this? Please, let me know before I spend couple bucks on a piece of hose.

[VinceDrake]

In my experience, not worth a crap. We used to try that on baffle-less 2 strokes, and all it did was smell really awful if you got it really hot.

We also tried chunks of inner tube over the end, and that made about the worst farting noise at idle!

YMMV
--Vince

[alonzo]

I have seen a heavy plastic water jug and a piece of hose routing the exhaust to the bottom of the can and filled with water. keep in mind that this was on a old flat head jeep and it was a five gallon bucket. you have to keep the rpm low so you do not push out all the water. and when it builds up to much heat you are bound to burn the hose. might try hydralic line that might keep the heat at bay.

[ExtremeModz]

I would ask that you reconsider your "stealth" bike. There are too many deaths and accidents already from drivers not being able to see motorcycles. If you make it silent you will be further increasing your chances of an accident and or death. Ever hear the expression loud pipes save lives? Well sure there is a limit and many American motorcycle enthusiasts take it way too far with open head pipes but stock or a bit louder is a good thing for your safety and other drivers.

I will say the more restriction that you add the quieter it will be and the less power you will have. There are many options for restriction like longer mufflers with more packing, smaller pipe, longer pipe. Even adding a downward tip will substantially decrease sound. You can use a more restricted air filter like stock and use the stock air box. If it were me I would start by welding on a 90 degree elbow to the tip of the muffler. You can buy them just about any hardware store or ebay and this will quiet it down quite a bit! In fact this is how they make our bikes pretty quiet in the first place by welding on a tiny tip to a otherwise large canister.

If you don't have access to welding or are not mechanically inclined you can even use good quality jb weld to attach the 90 deg elbow.

[Dragon]

With cell phones, loud music, and windows rolled up; cagers can't hear us no matter how loud our pipe is.

[fatboy250]

Originally Posted by Dragon

With cell phones, loud music, and windows rolled up; cagers can't hear us no matter how loud our pipe is.

Agreed. Any chance of getting a train horn?

[IronFist]

Horns save lives, but louder pipes????? No

Don't drive beside cars and you won't need loud pipes

[ExtremeModz]

I think I may have found your solution in a quest for a stealth bike. You might look into this one next time around. It's called the "STEALTH"

"Loud pipes may save lives, but quiet, all-electric motorcycles may save the planet. We were thinking of putting speakers on the bike to give it that rrr sound"

[warrior91]

Originally Posted by Dragon

With cell phones, loud music, and windows rolled up; cagers can't hear us no matter how loud our pipe is.

I beg to differ! :twisted: I am the guy most people shake their fist at...
If you can't hear my pipe you are deaf or 18 years old with a 2000 watt stereo!

[VinceDrake]

Thinking about it, if you were to put a dwonspout on the end of the muffler (Say about 50 Degrees or so) and point it at the ground it gives the fell of less noise. Instead of blasting the exhaust pulse in people's faces, you break it up a little bit against the ground, making it sound softer and less obnoxious. If the Down spout (available at your local Crappy Tire) was a decent size, it wouldn't cause any restriction at all....

Again YMMV, but it works on 1.2 tons, etc.

--Vince

[iMoose]

I've considered this before. :idea:

So zombies wouldn't hear me riding around town. Zombies are attracted to loud noises. :roll: Duh!

The smartest way to do it is by welding on a bracket to both support the extra weight of ...........

A big old car muffler from something designed to be quiet, like a Caddy's internal S-shaped deal. Combined with some nice street tires, then "they" won't hear ya until you kick 'em while riding by!

And incorporating a custom tin heatshield between the muffler and your new custom bracket is a VERY good idea. That thing's gonna get HOT!

The guys at my local muffler shop said it wouldn't be a problem, but they looked pretty confused.

[IronFist]

Defracting sound will drop the total 9db. That's noticible even with bad ears.

[ExtremeModz]

The downpipe would not just redirect the sound to the ground, it actually adds a good deal of restriction in turn further quieting it down.

[VinceDrake]

Originally Posted by IronFist

Defracting sound will drop the total 9db. That's noticible even with bad ears.

Defracting? That's awesome! Can I use it?

As to restriction, it doesn't have to be a redilulous long pipe, only, say about 12" and a guy could make it out of something kewl, like 2" aluminized exhaust pipe, it wouldn't restrict at all.

2" pipe by itself will flow approximately 400 to 500 CFM, no problem. 1 bend, subtract 50 CFM, so reasonably, the worst it could flow would be 350CFM, which would be about 3 and a half times what a 250 cc engine can possibly create at WFO, max rpms. No problem.

--Vince

[Dragon]

Pointing down like this?

[from a scooter]