Motorcycle exhuaust baffles

[jayhawkman]

Can anyone tell me what the inside of an exhaust pipe looks like. I am thinking about building my own exhaust but not sure how to build the baffles. Thanks

 

[aboard_epsilon]

Depends if its two stroke or four stroke .

if four stroke you can put a perforated tube surrounded by glass fibre into a 3-4 inch diameter outer tube ...with a lead -in at the front end.....that's about all a beginners up to ...which is what you are by the sounds of it ....not being nasty or anything

inner perforated tube size is dictated by engine size and how many silencers it has.

a two stroke exhaust is not a beginners job.

it works on a principle of back pressure ...and the engine will not work efficiently if you don't have this certain amount of it and the right precise distance away from the exhaust port.

all the best.mark

 

[Toms Wheels]

What size 100 cc 1000 1800cc's. Most V twin exhausts have no baffles at all, Short pipes tend to be nasty sounding, Sportsters, choppers mostly. The jap V-twins tend to longer pipes, as do FL harleys, these sound better, and run better. Baffles I've seen are tubes that have be pierced all around, (like the pattern in expanded metal non-skid steps) about a foot long inserted in the end. By the time you chrome what you make, you can buy new. Assuming you are talking V-twin, If its an inline four, that a different subject.

my wheels don't slow me down

 

[Michael Moore]

SCIENTIFIC DESIGN OF EXHAUST & INTAKE SYSTEMS

ISBN 0-8376-0309-9
Philip Smith and John Morrison,
Robert Bentley Inc.

cheers,
Michael

 

[speedsport]

I read some of this stuff and sometimes it's really hard to keep my mouth shut. "A little knowledge is a dangerous thing"

 

[jayhawkman]

building the exhaust for 1800cc v-twin.

 

[Motomoron]

I'll assume that for this 1800cc V-twin that performance isn't the paramount concern.

What is your objective? a certain aesthetic? I'd start by looking at all the offerings from Custom Chrome, BUB, Thunderheader, etc, etc. and see what's been done. Are you doing the whole thing, from the head pipes aft, or just the mufflers? do you want to go louder than stock?

Fabricating beautiful chrome exhausts has to be a colossal pain. Every weld has to be perfectly ground, and the whole system must be mirror polished prior to plating, plus the baffle and packing have to go in after plating.

Stainless steel mandrel bends are available and if you can tig weld beautifully taht can be an option.

I worked in the bike biz for a number of years, funnily enough at a dealership which was anchored by their Harley Davidson franchise (I'm like the opposite of a Harley guy, having roadraced Japanese sportbikes and ridden mostly European bikes since the 80's)and I had a LOT of experience sourcing exhaust systems for big twins. There's a lot of really loud ones, and only a handful that can be verified on a dyno to make decent horsepower.

 

[Michael Moore]

"More sound, less power" does seem to often be the case. "Less legality" and "more annoyance to bystanders" often seems to be a corollary result.

The last thing I want on the street is something that says "look at me!". That's fine for once you've parked, but I've not enjoyed it when the police have decided to look at me.

From first hand experience I can confirm that a single-wall steel muffler "rings" a lot more than an aluminum canister does. I spent a fair amount of time making my own steel silencer for a trials bike, and it was pretty horrible as far as noise went.

So far, the inside of the exhausts I've built have generally looked round.

cheers,
Michael

 

[Forrest Addy]

Curse ALL noisy motorcycles and the people who ride them. There's a few who like to buzz my street on quiet summer nights. It takes an hour for the crickets and frogs to crank up their orchestra again. That goes for the 2000 watt thump-mobiles too.

 

[Jim Williams]

AMEN, Forrest. Some time back I had a guy on a straight pipe Harley on my left at a stop light. The idle was loud, but I did not close my open window. When he left at the stop light change, I suffered terrible pain in my left ear from the noise. It hurt for hours, so some damage must have occurred.

Jim

 

[LD]

The shape of the pipe has a lot to do with sound as well. Straight pipes are significantly louder than those that flare out to allow the pulse to expand and then taper down to a smaller outlet to break up the sound once again.

You can make a baffle out of nothing more than a closed tube with a series of cuts or perforations around the length to break up the exhaust pulse. Use a smaller tube than the pipe ID and weld it onto the header. Slip a larger diameter tailpipe over it and weld that to the head pipe. Voila, you have your baffle encased inside your tailpipe. Belt sand and blend your welds smooth and take it to your chrome shop to finish.

 

[Forrest Addy]

How about a couple of capped pipes? Seal weld them right up. EPA friendly too.

 

[BREWSKI]

I almost lost my right eye to quiet pipes on my '93 FATBOY,almost totaled the bike,some little kid ran out in front of me in a curve,slammed on the brakes and the bike and I ended up in a 3 foot deep drainage ditch. BREWSKI

 

[SteveM]

Michael Moore wrote:
SCIENTIFIC DESIGN OF EXHAUST & INTAKE SYSTEMS
Philip Smith and John Morrison,
Robert Bentley Inc.

WOW. I thought I was the only one that read that! Very interesting reading, especially the parts about graphing pressure over time with a rotary valve and a bunch of manometers.

Steve

 

[aboard_epsilon]

I don't know how you guys in the US get away with having no baffles in your exhausts ...you must have next to nothing of an annual safety test ..

we in the UK would get an endorsement on our licences and a hefty fine ...if we were to ride around with no baffles .
in fact even with baffles ...if the police think it's noisy ...then it's a fine and an endorsement.

The bikes wouldn't pass the annual safety test (MOT) either.

All the best...mark

 

[Ries]

Mark- in most parts of the US, there is NO annual safety test.
In a few states they have em, but the vast majority do not.
And even if you do get pulled over by the police for a car or bike that is so damaged or decrepit that it is spewing black smoke or leaving a trail of parts behind, in most places that is not considered a "moving violation" so it does not go on your record as a traffic offense, and is not attached to your driving licence.

We are a cowboy country, and proud of it.

 

[aboard_epsilon]

We are a cowboy country, and proud of it.

lol


Them orange county choppers guys, the cops would love them here ...every bike that went out of their door onto the roads ...the police would be waiting for them...and issuing out summons like they were going out of fashion.

All the best.mark

 

[Dead Nuts]

It is easy to adapt a SuperTrap muffler to a custom pipe. Just use the end cap and discs and copy the internal parts and outer tube. I have done it for 2-stroke bikes and 4-stroke VW motors. You can add or subtract discs to adjust back pressure.

 

[Toms Wheels]

So does that Help!!! LOL

 

[jayhawkman]

Some of the replies where very helpful. The rest were well you can read them for yourself. Hard to believe how little focus some people have. Seemed to me a very simple question. I wonder if some here even read the post before givng there imput.