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View Full Version : too loud, what about my backpressure?



jd2210
06-20-2007, 11:27 AM
My new muffler on my big red is way too loud. Not just "man I sound cool" loud, but actually hurts your ears loud. I fear it's because I have absolutely no backpressure on it. The outlet on the muffler is a good 1/4 to 1/2 inch larger than the pipe going into it. (the muffler is acutally for a Dodge Colt, I have a trailer full of automotive exhausts left from selling our dealership +want to use what I have)

I guess my question is that if I weld a tip on with a much smaller diameter will that force the air to actually use the muffler instead of just flowing straight through? Is too much backpressure going to seriously hurt my performance? Will it even damage my engine somehow?

Right now the tip sticks straight out. Would even just welding on a down tip make much difference? I'm thinking maybe a bit for the people behind me, but I can be heard for miles right now and need to soften it up.

SWIGIN
06-20-2007, 11:41 AM
a turn down tip will make a difference but it will still be about as loud when your close to the bike

here is a pic of my turn down and from a distance it really quieted it down

jd2210
06-20-2007, 12:23 PM
a turn down tip will make a difference but it will still be about as loud when your close to the bike

here is a pic of my turn down and from a distance it really quieted it down

So if I'm trailriding will it help the guys behind me?

Erics350x
06-20-2007, 01:33 PM
if you do mostly lower rpm riding alittle back pressure would be beneficial to you. i'd close up 1/4 of the outlet.

atcsteve
06-20-2007, 05:02 PM
back pressure is good for low-end power,but not too much back pressure!Why not buy a used silencer,they are around $20 on ebay!!!!!!!lol

jd2210
06-22-2007, 10:36 AM
Well.... I welded a large washer on the end of my muffler to give it some backpressure and then welded a down tip on after that. It made A LOT of difference. It didn't seem to hurt the performace too much either.

Erics350x
06-23-2007, 11:36 PM
Well.... I welded a large washer on the end of my muffler to give it some backpressure and then welded a down tip on after that. It made A LOT of difference. It didn't seem to hurt the performace too much either.

LOL, I did the same thing to my wifes ATV.

Dirtcrasher
06-24-2007, 12:43 PM
My new muffler on my big red is way too loud. Not just "man I sound cool" loud, but actually hurts your ears loud. I fear it's because I have absolutely no backpressure on it. The outlet on the muffler is a good 1/4 to 1/2 inch larger than the pipe going into it. (the muffler is acutally for a Dodge Colt, I have a trailer full of automotive exhausts left from selling our dealership +want to use what I have)

I guess my question is that if I weld a tip on with a much smaller diameter will that force the air to actually use the muffler instead of just flowing straight through? Is too much backpressure going to seriously hurt my performance? Will it even damage my engine somehow?

Right now the tip sticks straight out. Would even just welding on a down tip make much difference? I'm thinking maybe a bit for the people behind me, but I can be heard for miles right now and need to soften it up.

You bring up a good point.. I wonder how these motors get any back pressure with some of these exhaust - like the DG and Cobra. Thats probably why the only gains are on the top end. I still like the SuperTrapps the best...

RedRider_AK
06-24-2007, 03:59 PM
You bring up a good point.. I wonder how these motors get any back pressure with some of these exhaust - like the DG and Cobra. Thats probably why the only gains are on the top end. I still like the SuperTrapps the best...

Well, where do you want the gains to be? Most aggressive riders I know, especially ones that have a manual clutch to use, are in high revs most of the time.

Dirtcrasher
06-24-2007, 07:51 PM
High revs are great, but being able to keep it in a higher gear through a tough, tight section is nice. Most of these antique 4 stroke pipes seem to take away the little bottom end a thumper has in stock form.

Lots of us ride tight trails where top end power isn't very usefull.

RedRider_AK
06-24-2007, 08:19 PM
Lots of us ride tight trails where top end power isn't very usefull.

Yeah I see what you're going at. Oh well, who cares where it's at, it's still POWER! :beer :beer

jd2210
06-25-2007, 08:37 AM
Just for the record, my top end before the backpressure was 48mph one way from my house and 53mph back to my house. Now it's 49mph and 52mph. I'm guessing the wind may have been just that little bit different because it feels exactly the same.