Why is it bad to just take the mufflers off my rocker and run just the pipes. with maybe a baffle in there. what makes it bad for the bike??? if anything. now i am new but i see it as the same thing as if a went out and bought straight pipes. a lot of the pipes out there are just as short as the headers (as you would call them) on my rocker. so i am having trouble figuring out why it is bad to do this. when it is a cheap mod to make your harley sound like one. let me know because i am lost on this, being new and having limited knowlege

 

Did I read that right? You took off ONE muffler? That's like asking whether your scales will balance with 10 stones in one and 2 in the other, man. ( The answer is NO if they're all the same size ) but to be a little more specific, an engine is a heat/air pump. Since one "lung" is behind the other, and both are air cooled, it's a very complex equation to get the correct air flow in and out of each cylinder and have it balanced. It would actually be easier if the two cylinders were different displacements, BUT you can't do that because the load on the crank must be balanced.

Walk with me here...that doesn't mean the CRANK needs to be balanced, it means there needs to be equal force from both cylinders in opposite directions at the same times...action and reaction. So since the rear cylinder runs hotter (or cools less, if you subscribe to the "hole theory" in electricty ) there needs to be different air flow characteristics for each cylinder. That's why a rear head won't fit on the front and a front on the rear.

Different air flow going IN means different air flow coming OUT to maintain the balance. I sure shoved a lot of info into a couple paragraphs, didn't I? It's complicated SOUNDING stuff, but not hard to understand if you read a little, think a little, read a little more.

And for the more versed, I realize that the Harley engines in general fire at different points in the rotation...but I don't want this poor guy's head to explode....let's lead the horse to the water before we drown him.

 

There are a couple of things to consider here. All engines are tuned to or designed for a specific pipe length. It doesn't always mean that there is a perfect length, but that different lengths will give different engine characteristics. Secondly, the amount of back pressure provided by baffles or pipe length or a combination of the two can make a significant difference to the way the engine performs. In most instances, changing pipes, however they are changed, will generally require a re-tune on the dyno. The pipe length can also make a difference to the way in which the exhaust gasses are scavenged from the cylinders.
Naturally, there are those who have made significant alterations without getting their ride re-tuned, but to each their own.

 

you'd better put that back on b4 it's 2 late,then go out and buy a real exhaust
system like everyone else does.$pend that money help this wretched economy