Straight pipe exhaust question

WaterDog

WaterDog

New Member
The kit i am receiving has the standard short pipe that points almost straight down from the engine with the little 1 inch long final exit portion. I want to make an exhaust pipe that reaches around and goes further back near the chain tensioner. I believe the standard 'EPA' certified pipes have some elements inside that restrict airflow. Wouldnt a standard 1" pipe (give or take) work just fine? I was thinking that not only would the air flow better, but it would also sound a little throatier. Is there something im missing with this idea or is it common practice?
 
Two cycle engines require a certain amount of back pressure to perform properly. A long, open pipe will probably not provide enough back pressure and will most certainly not make you any friends in your neighborhood. If you have the capability to fabricate a long pipe, why not attach the kit supplied muffler to the end of it? You'll have the best of both worlds...and extended exhaust and a muffler.
Tom
 
i was messing around with one of my bikes and made a 1" straight pipe about 3 feet long, with no muffler. when i fired it up, all the car alarms went off in my neighborhood, the lady next door had a heart attack, and my ears are still ringing.

seriously, it's really LOUD.

but the poo poo pipe or 2door's idea should work great.
 
A poo poo pipe will do exactly what you want. I got a poo poo and over all I like it. Sounds alot better then the stock pipe and looks cool.
 
I had a straight pipe on my bike for a while it was very load sounded like a lil chopper I loved the way it sounded but it did affect the performance. Of the bike so I got the sbp expansion chamber n I got power plus a nice sound
 
On a 4-stroke, a straight pipe will work fine if the length and diameter of are correct for the certain sized engine you're building it for. Same goes for expansion chambers on a 2-stroke....there are formulas to build tuned pipes for different types of applications. Many variables involved however.

Search and read....it's in here.
 
in run a poo poo pipe only cause i didnt know what an expansion chamber was when i ordered my poo poo

i like it for several reasons first it is more shaped to bike and does not extend to low i have bent my dads stick pipe in while travrsing oer rocky terrain where i have had no problems with my poo poo pipe

second the noise is quiter maybe only cause it puts noise behind and it makes a cool put putt sound

i rode it with the muffler off and noticed a increase in power but not worth the extra noise it was bad
 
bairdco said:
i was messing around with one of my bikes and made a 1" straight pipe about 3 feet long, with no muffler. when i fired it up, all the car alarms went off in my neighborhood, the lady next door had a heart attack, and my ears are still ringing.

seriously, it's really LOUD.

but the poo poo pipe or 2door's idea should work great.
Click to expand...

The stock muffler fell of on my recent project. It fell off about where the wider pipe meets the smaller one. I have just left it at the and I agree it sounds beastly. I have actually gotten an increase in performance while running, it just is twitchy at idle.
 
i made a megaphone exhaust on my race bike just to annoy everyone. it was a 6" straight header pipe with a stainless drink mixer cup welded to it (the kind they shake up martinis with at a bar.)

it was awesome. my phone has a soundmeter ap that measures decibels, but it only goes up to 100db so i don't know how loud it really was.

i dunno what it is, but i think race bikes should be loud. makes 'em scarier...
 
for my 4 stroke HS i chopped the flange and first 3" of curve from a stock 2-stroke exhaust and chopped/welded a few sections of old motorcycle handlebars together til i got something going down under the pedals and pointing right at the ground. with the echo off the ground, it's incredibly loud and yes, it gathers a LOT of attention. but so far i'd vote it's a good thing, because now the people in cars KNOW i exist. i just make sure to let off the throttle half a block from home. haha.
 
It's quite possible no greater harm has been or can be done to motorbicycling than this. Reckless riding, speeding, OUI/DWI, oversize engines, lack of safety gear - while all problematic and are ongoing threats to our ability to continue enjoying our comparatively unrestrained & unregulated activity, they're often secondary to what got noticed in the first place...

...the negative attention drawn from everyone other than the rider of that unduly loud bike.

Not to dismiss the other issues as unimportant but I bet if the statistics were available, the vast majority of traffic stops, tickets, impounds & even incarcerations involved such a bike, the ones that constantly irritate the neighbors, the pedestrians, that parked cop you just passed.

Please don't get me wrong, I'm usually known for "to each their own" and TBH I do enjoy the growl & screams of a well tuned engine... but a two smoker with the baffles pulled or a straight piped four stroke utility motor just doesn't make the grade. Neither has the preformance gained by a proper, tuned exhaust system which in both cases involves a bit more than chunks of handlebar. Yes, you may notice some small gain by gutting the stock pipe or ditching it all together - but that's not because it's the best way to get preformance, it's because the stock systems are often the worst possible and very poorly designed, not just excessively restrictive but not even as quiet as it could be for that restriction. I've expansion chambers with extended glasspacks and header wrap on my two smokers, not only is that quieter than stock it has far far better power than the stock pipe or stock with the baffles cut or pulled entirely. My four smoker has two 90° bends, header wrap and a glasspack with a diffuser plate added, far quieter than straight pipe and only a little louder than stock it only roars when the throttle is pinned - at cruise speed I can hold a comfortable convo with another rider without even raising my voice. Interestingly I got a minor, but very noticeable gain in preformance when I added that plate.

Amazing things can be achieved with a bit of experimentation, in my opinion the best systems combine preformance and reduced noise levels, usually when that combo is found it's a system that ends up being comparatively quiet at idle & cruise, it's only loud when you get on the throttle. Best of all worlds I figure, comfortable for the rider, doesn't anger everyone and you get the vroom when ya need it.

While I'm not trying to reprimand those that are only doing what they wish with the bike they've built, rather offering some suggestions and food for thought - I will say the most noticeable effects from "loud pipes" are traffic stops, neighbor complaints and noise ordinances... and there's some very troubling aspects to that ordnance thing. Check out what loud pipes got us here in Maine, consider the possibility and consequence of your states following our lead;

http://wheels.blogs.nytimes.com/2011/06/28/on-noise-standards-motorcyclists-split

http://www.mainelegislature.org/legis/bills/bills_125th/billtexts/HP037002.asp
 
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