Packing baffles

[BRP Tourer]

Sorry if this has been discussed before, I did a search and found nothing...
I am rather new to 2 strokes but rather well versed in engine tuning. I have had my GT550 running for a while now and have finally accumulated enough pieces to have a decent factory exhaust on it (the original was all busted up). Anyhow, as I installed the new pipes I took out the baffles to clean them and most of the packing was coming apart or missing so I just put the baffles in with no packing as I had none to replace it with.
The bike seems to run well and to me is not annoying loud , has a nice crackle to it at idle. Jetting appears to be spot on. When looking at the design of the exhaust I can see how the baffles direct the flow of the exhaust, but it doesn't look like the packing would have any effect on the flow, just the sound.
My question is... does the packing have any effect on flow, or just noise control? As I said, it seems to run great now, but I am wondering if it would benefit to pack them.

[H2RICK]

BRP, basically the packing is there to take that "crackle" out of the exhaust note so that you don't annoy your neighbours...or the local constabulary.
The original packing is a kind of very fine strand wooly kind of fibreglass. I have NOT been able to find anything exactly like that particular form of packing......and, believe me, I've looked.
My 550 has the original packing still in place and it's in good shape but one of these years it WILL need to be replaced.
The aftermarket offers packing for 2 stroke dirt bike baffles from 2 or 3 different sources but all of them use much coarser fibres which make a much stiffer batting.....almost like what you would find in a fibreglassing kit for boat repairs and that kind of thing. It CAN be used but it's a lot harder to work with, especially for the two smaller baffles in the #2 pipes.
I/we need to do some more research in this area.

[BRP Tourer]

Thanks for the reply... around here noise control is not much of an issue, it seems even without packing my bike is one of the quietest vehicles in the neighborhood, and I ride gently in town. I am more concerned if it affects exhaust flow at all.

[tz375]

I wrap mine in regular MX bike repacking kits. Some are a little different but they all work. I think Moose was the brand name but I bought whatever the dealer could get out of the TR or Parts Unlimited catalogs.

Packing doesn't make much of a difference to performance but they just run smoother and quieter packed and get rid of the annoying crackle. In other words they take out a lot of the high pitch noise which is what many people find annoying.

[Barry S.]

My 750 has no packing and is very quiet, I wouldn't mind if it had a little more crackle to it.

[Craig380]

My local bike shop sells bags of MX silencer packing 'wool' which is soft and glossy, rather like angora or similar.

It's about $5 a bag, and will do two complete sets of exhausts. It's DEFINITELY necessary with the Allspeeds I have

[oldjapanesebikes]

It's DEFINITELY necessary with the Allspeeds I have

+1 one to that ! I packed my Allspeeds with what I thought was enough, and then added more after a test ride For my bikes with stock exhaust systems though, I haven't used any packing in them for over 20 years now.

[H2RICK]

My local bike shop sells bags of MX silencer packing 'wool' which is soft and glossy, rather like angora or similar.

Yes, I've sold some packing like that, Craig, but it IS different from the stock packing in my 550 baffles. It would probably work quite nicely but I'd still like to find packing that's closer to or exactly the same as the original stuff.
The search continues.....

[BRP Tourer]

I have some fiberglass matting from doing some boat work that is pretty coarse, you might try local boat shops or other places that do fiberglass repair. They usually buy it in bulk and may sell a chunk to ya reasonable.

[pennell]

I am going to clean my baffles out very soon, so if I strip all the packing off (most likely soaked with gasoline and soot) it will sound better AND not hurt performance? The one thing my stock pipes lack (to me), is the real 'pop' of a 2 stroke.

[tz375]

I would not go that far. The idea is that noise waves travel out and dispersed in the packing but the gas flows straight out through the perforations as if it were solid.

Removing the packing will change gas flow and that will potentially make a difference to performance. How much? I can't say. We'd have to try one on a dyno back to back to determine that.

The sound with stock pipes is a little muted, but without packing it just sounds a little nasty and raucous without offering any improvement.

Back in the day Yamaha twins had similar baffles and the popular race trick was to replace the baffle tube with a straight tube up to the packing and then the tail part was packed like a stock pipe. I seem to recall reading that the packing was needed to make the pipe work.

[Craig380]

It will vary from bike to bike, and of course a stock Suzi stroker isn't in RG500 states of tune but I remember reading an article that tested various mods on a Honda CR125 racer on the dyno ... as I recall, a fresh, tightly-packed end can on the stock pipe gave an extra 1.5bhp at the top, compared with old packing that had done several meetings.

For optimum power, it seems it's either got to be a straight-through stinger tube with no perforations ... or if there are perforations in the tube, it's gotta be packed tight ....

[Suzsmokeyallan]

Pro-circuit used to offer a very tightly bound batting mat that was like dense fiberglass for their silencers. I wonder if they still make it this way, its worth looking into.
For the Suzuki triples you can separate this mat in half of its thickness which will work perfectly at this size for wrapping on the baffles two turns.
I don't put any on the inner pipes of my Buffalo since the flow is so subdued being its split into two.

[james]

hvccycle lincoln nebraska has the packing as close to original as i have ever found