I have had several go karts and wild weed eaters that i took off the muffler and gained some serious rpm and never has caused a prob with the way they run. I know to some noise is an issue and all but Its not an issue for me. I just welded up a aluminum 1" id header for my bosses 2 cyl ryobi weed eater that he wont give to me no matter how hard I begged him,....... anyway, I noticed that the rpm increased over 1500 more than with a muffler, and at night it sounds and looks wicked with the flames and sound, any feedback appriciated! MIKE

Most mufflers used are just deflectors. These "mufflers" offer little muffling capability but nonetheless offer more than a straight pipe. The reason we use them at all is to keep the neighbors happy. Also you have to remember that the things that the engines are on actually fly. This makes them easeir to hear because there are no trees, hills , houses, or anything else to block the sound from reaching everything under it. It is not like being in the woods cutting wood with a straight-piped saw, yes it is loud, but the sound does disipate some before leaving the wooded area after bouncing off all the trees. If you fly something like that for long you will have the neighbors taking notice. And most of the time it is attention you do not want.

If you want to make some real power buy a fully tuned pipe with a silencer. Straight-pipes won't hold a candle to an expansion chamber on a 2-cycle.

Put an open megaphone (like the bell of a trumpet) on the end of a straight pipe.
That should make some impressive noise.

I guess the answer lies in how old you are and how much longer you want to continue to hear sounds like the rest of us that still can.

The first frequencies to go are the higher ones, later the lower ones. As the tiny hairs inside your ears are killed by excessive noise, they never regrow. Each one lost is a small loss in your hearing. Losing them in such a slow manner is insidious. You don't realize that you are losing your sense of sound until it's far too late.

Todays crop of the younger crowd will find this out much to their dismay with the use of the super loud, heavy bass, auto stereos they are listening to.

Ya gotta love the sound of straight pipes, less weight too.

Well put. I hope a few people read this and take heed. At least wear some kind of hearing protection when you are around these things unmuffled or you WILL regret it later in life.

Ya know when you call me all those terrible names and are so mean and nasty and I don't respond? It's not cuz I have such great control, it's cuz I never heard you.

Those pipes were great, tho. I have never been able to figure out why they don't sound as loud as they used to.[]

That's what I am saying Pat. You need those straight pipes now just to make sure you hear that your engine is running.

Kidding aside, If you want to run loud, at least use ear protection on the ground. And that goes for shooting or any other loud activity. When you become older you will find out why.

Yes, don't expose yourself to loud noise when you don't have to. Trust me I get tired of saying "What did you say"

Huh? I can't hear you, but then I can't hear very much any more. They told me, back in the 60's & 70's when I was doing formula 1 pylon racing, to wear ear protection. I wish I woud have listened.

Most mufflers and tuned pipes provide exhaust back pressure that is needed to obtain the most H.P. from a 2 stroke engine. As for tuned pipes, the length of the header in relation to the expansion chamber affects the RPM as well as the amount of horsepower that an engine puts out. Commonly, tuners will refer to a properly tuned engine as "on the pipe" when it is running the strongest.

In the case of our aircraft engines, the load (prop diameter and pitch) is also a consideration in a tuned pipe application. The back pressure is needed so that the engine can breath most efficiently, exhausting as much of the burned fuel as possible without exhausting the next air/fuel charge which is moving up the transfer ports as the piston is moving towards the crankshaft. The distance between the closing of the transfer ports, (by means of the piston covering the ports) and the closing of the exhaust port is commonly called the port timing.

It is a mistake to believe that running the engine without a muffler or tuned pipe will increase the performance. It may increase the RPM's, that does not always translate into more HP. A quick look at a power curve chart or "power band" will confirm this statement.

On the other hand, if you are looking to lose your hearing in short order, or irritate your neighbors quickly, the straight pipe is the way to go.[:'(]

Yep, and not to mention losing flying sites.

I fly at a feild abouty 5-6 miles away from anyone and I use the electronic game ear i use to hunt with, yes I am an avid hunter, dont hate me!, but I like the loud sound of a stung out weed eater, but i do take everyone around into concideation, but normally it just me and my buddy matt, we wear ear plugs to do straight pipe on anything, especially the honda, thats a maen straight header enging, 499fhp, 542 N2O horsepower.