no silencers?

[ehall1]

if i rejet for no silencers will i get a jump in H.P.? reminds me of open headers on a car less back-pressure more H.P.. got stock exhaust now but if i opener up and get rid of silencers and jet richer will i gain any H.P.? still 2-stroke new yah no what i mean? aint worried bout noise(F*#&K) the neighbors. lookin for cheap H.P.................ed

[Smokin'Gun]

Where does everyone get this idea that sliencers provide backpressure. The expansion chamber provides the backpressure which in turn helps keep the fuel in the cylinder when the exhaust port is "open". Silencers are only supposed to make it quieter. I can see maybe if you run a gutted silencer but no silencer isnt going to take away a whole lot if any backpressure. 2-strokes arent like 4-strokes you can actually run them with no pipes at all just a small header or whatever because there arent any valves to burn up if theres no backpressure.. the thing is that they arent going to run real great. Megaphone exhaust was popular in vintage snowmobile racing before expansion chambers became possible and they dont provide any backpressure but they boost h.p. alot more than just a muffler does. Maybe you can get the idea from this. As you can see.. no silencer. But the answer to your question is that you probably wont see a noticable difference in power if you jet it right. If you take the sliencer off and dont rejet you might see a loss in power tho.

[ehall1]

so all the needed back-pressure is created in the first pipe or head pipe and freeing up the rest of the system is pretty much worthless? silencers are only neede for just that (silencing)? just was wondering cause at the local fair it seemed like the highly modified class was running straight pipes. dam them things were flying!!!...........................ed

[370banshee]

ok where do i start... first off the reason that drag quads don;t use a full silencer is because the engines are built very different than your normal banshee engine. as for back pressure and expansion chambers.. the expansion chamber doesn't provide back pressure but rather it provides a reverse resonance that scavenges the cyl.. thus removing exhuast and providing a fresh rush of fuel/air mixture. the silencer provides the back pressure.. now in a 4 stroke you don;t need the back pressure to scanvenger the cyl because the fact that is has a valve.. see a two stroek just has an open port and needs teh flow to remover the spent gases.. the 4 poke has the "PUSH" to get rid of it... so in other words keep teh silencers on.. the problem with banshe stock pipes are that the expansion chambers are way wrong and they are very very heavy.. buy a good set of pipes and scrap the french horn stockers..

[ehall1]

Originally Posted by 370banshee

ok where do i start... first off the reason that drag quads don;t use a full silencer is because the engines are built very different than your normal banshee engine. as for back pressure and expansion chambers.. the expansion chamber doesn't provide back pressure but rather it provides a reverse resonance that scavenges the cyl.. thus removing exhuast and providing a fresh rush of fuel/air mixture. the silencer provides the back pressure.. now in a 4 stroke you don;t need the back pressure to scanvenger the cyl because the fact that is has a valve.. see a two stroek just has an open port and needs teh flow to remover the spent gases.. the 4 poke has the "PUSH" to get rid of it... so in other words keep teh silencers on.. the problem with banshe stock pipes are that the expansion chambers are way wrong and they are very very heavy.. buy a good set of pipes and scrap the french horn stockers..

thats easier to understand. apparently he didnt catch the "new to 2-stroke line"

[Flattrack]

370 dose it again.. Now a little more information for the new guy .DID you ever ride in a car with a turbo and you feel the turbo kick in. Well thats the same as a two stroke coming on the pipe or as most people call it the power band. The Exhaust on a two stroke is designed to produce Power at a certain point in that motors rpm range. This is all designed in to a pipe from head to final exhaust outlet diameter. A pipe built to run a silencer is designed to operate with a particular exhaust bleed off (the rate of exhaust leaving the pipe) this determines the speed and length of the waves produced in the expansion chamber..

Now a open drag pipe is designed to perform best with out a silencer but then again they usually have a smaller outlet than a pipe designed to run one. causing the correct bleed of.

When a builder builds a 2stroke motor pipe design is a major consideration in port configuration. If you ever want to build a strong motor and send your stuff out talk to the builder first and see if he ask you what pipe you are planing on running probably not. This is a critical part to build the most efficient power possible. I for one have quite a collection of pipe specification on most of the major exhaust out there built for 2strokes this allows me to port a motor to the exhaust that a customer is on using there for they can get the most power for there dollar...

[370banshee]

Originally Posted by ehall1

thats easier to understand. apparently he didnt catch the "new to 2-stroke line"

i tried to not be confusing... sorry if i was...

[jwalkerblack]

First I just want to say that is a cool picture, smokin'
Second that was a great question e-hall, I had always wondered what purpose the silencer served on 2 strokes, thank you 370 and flattrack for some great explanantions, learn new stuff here everyday that is why I love this site!!!

[370banshee]

no problem thats why i'm here.. to help other riders and to learn more myself.... well and to make fun of jason

[ehall1]

Originally Posted by 370banshee

i tried to not be confusing... sorry if i was...

no they were all great explanations, i apparently still got my head in a 4-stroke (car not quad i aint that stupid) frame of mind. just seemed to me any restriction in the exhaust would cause back-pressure and then loss of power. guess ill have to break down and sell the kids to geta good set of pipes. so much for cheap horsepower. like they say how fast do you wanna go? thats easy how much money yah got? thanks....................ed