How short is to short

[apl2964]

My exaust was shot on my 78 550. So for a quik fix i pu on four straight pipes about 18" long, they kick out down below my feet. Sounds pretty sweet. How bad will this mess with my performance.

[odl777]

I think straight pipes take away from topend but give alil at bottom. nt sure though may b the other way around. But i know that performence wise it is a lil better to have a muffler. But you dont lose much probly not even noticable.

[katoranger]

It should be the other way around. You essentially have an open exhaust so the carbs are probably lean now. If you want to keep the straight pipes you will need to rejet.

Allen

[bj]

[step up on soap box]

Please, please, please don't run straight pipes. Excessive noise is one of the greatest problems facing the motorcycling community and it's a self-inflicted wound.

Here's a link to some great information about the cost and consequences of riding an excessively noisy bike - http://www.amadirectlink.com/legisltn/positions/noise.asp.

Noise does not equal power. The only thing it does is create problems for all of us.

[step down from soap box]

[Billy Ricks]

You could easily burn your exhaust valves with them too. At least run some shortie glasspacks with them.

[katoranger]

I had a friend that did just that to his valves. I don't care for the noise and my neighbors don't appreciate it either.

Stock is cool\\/

[apl2964]

I built a custom 2 to 1 exaust lastnight. The nice thing about the four cylinder is its not that loud. If i drive respectfully iwont bother anyone. I compared the noise to my yz 250 lastnight and its not even close. Its super quiet below 4000 and gets some bark when your really on it. I only paid 50 dollars for this bike and have a hard time buying a 200 doller set of header pipes. Thats my case. I will only have $200 in the hole bike in perfect running order

[Billy Ricks]

Thats my case. I will only have $200 in the hole bike in perfect running order

It may not stay that way for very long if you run it with short open pipes. A set of valves, gaskets, valve seats, and the rest will set you back more than that.

[m in sc]

I'd get a set of some shorty mufflers, run 4 into 4's... i know a place that has a butload of bassani glasspacks for like 20 bucks a pop. as far as being too loud... well, i run my rd with just about open stingers and the cops leave me alone... don't really have a choice as the pipes are designed to be run that way. only time a cop pulled me over is because he checked to see if my 'dirtbike' had plates.
good on ya going cheap! been there, done that. i always say: poverty in the mother of most invention. (well, it always was in my case):-D

[apl2964]

Ya i just dont have any money to spend on gas thats why i bought the bike, Otherwise i would rather drive my truck to work everyday. My budget for this project is super super low, or ill have to eat egg sandwitches for the rest of the summer. Ive seen lost of guys on here having 4 into to 2 pipes, and its no different then the harley guys running short straighers, or race car having just headers. It doesnt take alot of pipe to get the vavlues to cool properly. I know that ive worked on engines my hole life. I just wanted to know if it would hurt my 550 performance wise, If it blows ill go back to my truck before i put 80 dollars in mufflers. I know for a fact that there is less exaust temp with less back pressure, its the valves cooling inproperly that causes them to worp. I didnt ask for preaching i just dont want to loose any hp on my little 550. Thanks

[Billy Ricks]

You asked and I answered, if you consider that a lecture so be it. Unless you tune the engine to run the pipes you are asking for trouble.

http://rmhfaq.com/pipes.htm

"On the question of installing open drag pipes:

"unless you have had some engine modifications to allow for it, you _will_ be down on power (maybe more power than the stock, but less than if you used "tuned" pipes). Engines are built to compensate for a certain amount of back-pressure (i.e. the valves opening a little earlier), and if you remove the backpressure, the valves will be opening too early, letting some still-burning fuel into the headers. ... because of this, you can suffer (in extreme cases) from burnt exhaust valves if you hammer it too hard..." -- Mike Kelly"

[Llamaguy]

I have never been irritated by "noisy" exhaust on cars and trucks AND bikes. They one's that are a pain are the ones that just defective, i.e. the junker with the whole in the muffler that make more noise at idle than my bike. A properly functioning exhaust is all I ask of people. Except for the really cheap ricer mufflers, but I think that those are defectively engineered.

Besides, I'm going so fast that you can only hear me for a second anyways. There was one time when a Harley ride went by for a few minutes, that was kind of annoying but only because it seemed like it would never go away.

I feel that excessively loud stereos that are more of a problem than exhausts. Most exhaust is higher pitched and doesn't travel very far and doesn't penetrate buildings. Were Dual band pass boxes that you can buy at Wal-Mart will play a few tones that travel forever and will vibrate an entire house. The only way a vehicle could do that is a large number of Harleys or a bunch of modified pickup trucks.

I live on a very busy road (less than 30ft from door to curb, I hardly ever notice bikes to be "loud" when the windows are closed. And even then not even close to the bass tracks that are being played that shake the windows.

To summarize, unless you live next to a race track or pseudo race track, exhaust probably isn't your worst enemy.

[Llamaguy]

similar, A guy installed exhaust cut-outs on his car similar to mine, here's what he had to say:

Well, as i have been finding out each day, more and more things SUCK about it. It is the WORST thing i have EVER done to a car... I took the car to a dyno and found results back about the cut out and my nos...When i took it to the dyno TODAY i found out something HORRIBLE about the exhaust cut out. On our Porsche's, you will LOOSE HP AND TORQUE, i lost 35HP & 37 Torque!! I feel terrible about it! Last weekend i installed the cut out and this week end I'm going to cut it out and weld in straight exhaust again. please save yourself of the agony I'm going through...i love loud cars, so trust me on this one you WILL HATE IT and you get NO HP GAIN...