mcferreira100 Posted May 19, 2014 Posted May 19, 2014 Can anyone explain to me the story behind the packing in a 2stroke exhaust. Removed the baffles from my RD350 today and noticed no packing left in there...only a few strands which had unwound themselves. What is its purpose, can I ride without it or must there be packing in there?
Moderator drewpy Posted May 19, 2014 Moderator Posted May 19, 2014 absorbs the noise and changes the frequency ie lower to be more socially acceptable. I just managed to get a peashooter exhaust from the 70's, now they are loud
mcferreira100 Posted May 19, 2014 Author Posted May 19, 2014 Reducing noise is logical..but I am wondering about backpressure and performance. By the way after doing some research I think the leftover strands is probably the wire used to hold packing in place..ie: there is NO packing left in there..or it was removed.
Moderator drewpy Posted May 19, 2014 Moderator Posted May 19, 2014 Reducing noise is logical..but I am wondering about backpressure and performance. By the way after doing some research I think the leftover strands is probably the wire used to hold packing in place..ie: there is NO packing left in there..or it was removed. there's no back pressure from the packing as it works by absorption.usually goes round a straight through perforated tube
Moderator Cynic Posted May 19, 2014 Moderator Posted May 19, 2014 The packing makes a little bit of difference but not much. Just softens it a little. Certainly has no affect on performance. Cleaning the inside is far more important. Its all to do with reflection and gas movement, carbon build up disrupts that. Badly coked pipes can cost you 10hp easily. As well as fudging that awesome 7000 rpm punch.
slice Posted May 20, 2014 Posted May 20, 2014 I had a Honda 150 4stroke many years ago and it sounded like shit with the baffels in so being the tit that I am I took the baffels out and it sounded great, trouble was that the back pressure was not enough and the engine ran really hot, after about 3 weeks the internals let go and I spent the next week and the next months wages putting it back together, packing does reduce the sound making it less harsh but you have to make sure the jetting is altered to take into account the loss of pressure, just my opinion you understand as others are much more up to date with more modern machines and their foibles but my advice is, if it came with it then put it back how it should be.
mcferreira100 Posted May 20, 2014 Author Posted May 20, 2014 Trying some oven cleaner in there to give them a clean. Sprayed whole can of the stuff in...will leave overnight.
Preload Posted May 20, 2014 Posted May 20, 2014 As said the wadding just absorbs the sound waves They sound crisper without.
Moderator drewpy Posted May 21, 2014 Moderator Posted May 21, 2014 I had a Honda 150 4stroke many years ago and it sounded like shit with the baffels in so being the tit that I am I took the baffels out and it sounded great, trouble was that the back pressure was not enough and the engine ran really hot, after about 3 weeks the internals let go and I spent the next week and the next months wages putting it back together, packing does reduce the sound making it less harsh but you have to make sure the jetting is altered to take into account the loss of pressure, just my opinion you understand as others are much more up to date with more modern machines and their foibles but my advice is, if it came with it then put it back how it should be. 4 stroke exhausts are totally different. They are packed inside the chamber normally with baffles to provide backpressure for more torque, whereas 2 strokes are packed externally. my xs has a Yoshi through exhaust but with external packing and jetted accordingly
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