Back pressure

[welderman85 53]

Hello all. I made a couple of stack mufflers for my horses a while back but there were pretty loud and my little son didn't like the noise a whole lot so I cut them apart and installed a baffle and some motorcycle muffler packing. It's nice and quiet now but could this cause to much back pressure? And what would ok t harm. TR Hank you

[Achto 26,500]

If you had too much back pressure the engine would seem sluggish, almost the same as if the air filter was plugged or the choke was not open all the way. If your engines performance did not seem to change much you should have no worries. On the other hand, too little back pressure can eventually damage exhaust valves.

[Tuneup 1,416]

A typical motorcycle performance muffler is a straight through affair - I had one on my Bandit 1200 and you view daylight through the passage. The sound volume is adjustable by the number of holes drilled in the main pipe. The more holes, the more the packing has the ability to absorb sound. It depends on how your muffler is assembled. If it's like the one we've seen made in a recent post, one of which I own, it has a trap pushed into the middle which forces the exhaust through the holes into the outer channel, around the obstruction and then and back in. If yours is same, you are forcing the exhaust through the packing and that's not a good thing. If I had me a welder, I'd love to make a nice glass pack for the K301. They are sweet.

[welderman85 53]

I built it the way you described with the exhaust going through the packing. Not to sound stupid but why is it a bad thing. Thank you

[Tuneup 1,416]

Never seen packing in the direct exhaust stream. I didn't know it could take the heat. Like was said, if the engine doesn't labor and can rev quickly, and if the packing doesn't burn, you have a nice muffler going for ya.