Silencer Packing

[robinson373]

just curious what would happen if I got rid of the packing in my silencers, other than being extremely loud, would it increase performance. My roommate lost the back to his silencer and the packing on his 125 and it ran like a streak of shit with a lot more torque. He just needed ear plugs.

[Blue Duece]

like with any motor that runs good there has to be some back pressure, id say pack them up tight and you will feel a pinch more bottom

[01 Blue Screaming Banshee]

How often do you repack the sclincers, and is this needed?

[frocashmoney24]

pack em every 20 hours, pipe company's say theres a major loss in power, but ive never felt it, but backpressure is def needed so repack them, not hard and not expensive

[Forcefed]

It really is a good idea to keep your silencer packing in good working order to maintain peak performace levels.

 

Think of it like this.....

 

All two strokes are extremely dependent on exhaust design. Without a specific amount of backpressure pushing the unburnt fuel back into the cylinder (supercharging effect) the engine will NEVER run as well as it should within a specified operating range.

 

When the engine "comes on the pipe" or "hits the powerband" what do you really think is happening?

 

And when you realize just what is taking place with the above, contemplate what the effects of changing the backpressure are.

[01 Blue Screaming Banshee]

How do I repack them?

[Ultimateduner]

Its simple to repack them,

(buy two packs of silencer packing at a local dealer.)

First un srew all the screws at the very tip of the silencer.

Then try pulling on the unscrewed end of the pipe. after it comes out you should see a kind of metal hose looking thing. tightly roll the paking around it and shove the end into the back of the silencer. Then repeat for other silencer.

[Ultimateduner]

Without the packing you lose performance!!

[MotulMonsta]

You got ot a little wrong there forcefed. Back pressure is the enemy. If your theory was true, stock pipes would put out gobs of power. Anyways pipes are designed and "Tuned" to operated under specific conditions. The motor puts out a soundwave that's related to the harmonics in the motor. This soundwave travels down the pipe and is reverbrated back into the motor where it pressurises the incoming charge. This soundwave deflection is directly related to the size and shape of the expansion chamber. When the soundwave being reverbrated back into the motor and the harmonics of the motor are in "Tune" then power is made, lots of it. Hence the term on the pipes. When you take out the packing you upset the "Tuning" of the pipe..likewise if you leghthen or shorten the silencer as well.

This is my understanding of it and explains the necessity of a well packed silencer.

[Blue Duece]

you need some back presure or the end of your pipe would be 6 inches round instead of 2........

[FadedDreams]

And when you buy packing,stay away from the stuff on Ebay.It doesn't last very long.

[MILO]

pack em every 20 hours, pipe company's say theres a major loss in power, but ive never felt it, but backpressure is def needed so repack them, not hard and not expensive

every 20 hrs?? mine are probably due for repacking after last summer of riding, but is 20hrs necessary?

[frocashmoney24]

thast what ive read, but if you think about it 20 hours is a long time for some rolled fiberglass with heat and oil aint it?

[MotulMonsta]

Well, you can go as long as you like, the bike will continue to become louder and louder as the packing wears out. Unless your racing for points in a championship you can go a bit longer then 20 hours. I replace mine yearly and with any major overhauls.

[350duner]

Yes on a 2 stroke the returning sound wave (determined by the expansion chamber design) reverbarates back to the exhaust port. Due to the design of 2 strokes some of the unburnt intake charge escapes out the exhaust port with the exhaust on the exhaust/intake stroke of the piston. The idea is to tune it so the sound wave slams back into the exhaust port AFTER the exhaust escapes but just AS the fresh mixture starts to pour out. This forces the unburnt mixture back into the cylinder before the piston closes off the exhaust port where it can all be burned. That's why pipe design is to critical to performance.

I don't think the amount of backpressure in the stinger really affects performance much although different stinger lengths do, controlling how fast the exhuast can escape. I have a CD-ROM that LRD was handing out at their shop advocating keeping sound levels down. It shows Arlan with a 250r on the dyno. He does a dyno run with a silencer that has most of the packing blown out, then does another run with a freshly packed silencer and it made power power over the whole curve. I'd say keep it packed for the simple fact that I'm sick of riding areas getting closed off. We have a 93db limit here and it really sucks. It's $175 each time they catch you (and it's hard to do 93db with anything besides stock pipes). Don't need anymore of that crap.