ATV Florida Forum

A friend of mine has a 1996 model polaris 500 and he sunk it a while back. He said that he he had it to where it would idle afterwards but it ended up blowing his muffler apart. After it blew apart it quit running. He asked me about a muffler and I told him to get an aftermarket muffler, but someone told him that it he needs to buy a stock muffler because it would not run right because of the back pressure the stock mufler has on it. Is this correct.

No. Any muffler is going to provide some backpressure, just some more than others. With more backpressure present, it will give more low end power. But with a more free flowing muffler, you will loose some low end but pick up power in the mid/top range.  With a better flowing muffler the exhaust will be more susceptabile to back firing. But if he did get a better flowing one he may need to rejet the carb. Maybe that's what he is referring to.  Hope this helps. -Mark

I ran into a similar issue on the YFZ where I over modified the stock can. and well that is exactly what happened to mine. no back pressure. soon as I strapped on the slip on pipe it fired right up.

I would not recommend rejetting if all you change is the pipe. A pipe only lets air OUT of the motor, rejetting will require more air to ENTER the motor to compensate for adding more fuel to the mixture.