I want to repack my mufflers.

jbswear · Post by **jbswear** » Thu Feb 26, 2009 4:25 pm

I'm pretty sure that the baffles on the GT380 are shot. I know that to remove them, you pull the bolt out and then the baffles should slide out the rear.

I've never worked with fiberglass packing. Where should I buy it and can you give me any advice on how to do it? Safety considerations?

Coyote · Post by **Coyote** » Thu Feb 26, 2009 6:13 pm

Baffles can get pretty stuck over the years. Yes they should slide out but they probably won't. Use a hook on a slide hammer to coax them out. And yes, they are retained by that one bolt only in the access window under the muffler tip.
You can use household fiberglass if you wish, but a better choice is to go to a local dirt bike shop and get the real thing -- made for bikes. You will need some light gage soft wire. The packing is held in place by this wire. There is usually a diagram on the package that tells you how to work with it.

This is a generic diagram off a pack of Moose brand packing I have on hand. I like to make a complete wrap (talking wire here) around one end. then wrap in a spiral toward the other end, spacing about 1" apart. Again a complete wrap and start back the other way - cris crossing the first wrap as you go. When you get back to where you started, cut the wire and make a couple off loops around the full circle wrap you started with. This forms a wire cage to hold the packing in place. Neatness is NOT an issue here

Note: don't over buy. I package was enough to do a GT750.
http://www.mooseoffroad.com/

jkevinlilly · Post by **jkevinlilly** » Thu Feb 26, 2009 6:41 pm

If you have a gas grill handy, after you take the old fiberglass off the baffles, you can throw them on the grill for awhile and burn off a lot of the accumulated oil, carbon, and other crap that they will be covered with.

Barry S. · Post by **Barry S.** » Thu Feb 26, 2009 7:39 pm

It's only a small spot on the baffle near the end that is wrapped with insulation, most of the baffle is not, it's inside the pipe.

jbswear · Post by **jbswear** » Thu Feb 26, 2009 10:02 pm

Thanks guys. I appreciate the help.

Two questions...

What is the fiberglass supposed to do--what's its role?

And, um, forgive me, but what's a slide hammer?

tz375 · Post by **tz375** » Thu Feb 26, 2009 10:48 pm

The last 6 inches or so of the baffle is a perforated tube and the wadding is wrapped around that. Sound waves radiate out though the perforations and the fiberglass absorbs those pressure waves and dissipates them.

The gas doesn't flow out there, but the noise pressure waves do and that's what keeps it quiet at virtually zero cost to your performance.

chainsaw · Post by **chainsaw** » Fri Feb 27, 2009 6:52 am

If you want stinger effect and sound (loud), where the perforated area is, wrap it first with evtra heavy duty aluminum foil then wrap it with the packing. this is a method a drag racer told me. dont know if it has any effect on performance but it sure sounds good!!!

gyrocfi · Post by **gyrocfi** » Fri Feb 27, 2009 10:04 am

Alrighty then!! never thought about wrapping with aluminum for noise effect. gonna give it a try on one of my RDs. Ringgg Dinngggg!!

tz375 · Post by **tz375** » Fri Feb 27, 2009 1:09 pm

And people wonder why city ordinances are being introduced to ban noisy bikes.

One of the most annoying sounds on the planet is an unmuffled 2 stroke. It's unnecessary and doesn't help performance. Our race bikes are all muffled and they sound sharp and clean and just enough sound to keep people awake but not enough to piss people off.

Ok so I do own a 1973 TZ250 with stingers but I'd never run it that way - even at the track. It's noisy enough to cause serious and permanent hearing damage. My RZ sounds great with cans on when it hits the powerband and rips.

Did I mention that I hate crappy sounding two strokes with bodged baffles, missing baffles and straight stingers?

rbond · Post by **rbond** » Fri Feb 27, 2009 1:52 pm

Would 'safety' wire be suitable to use in retaining the fiberglass?

H2RICK · Post by **H2RICK** » Fri Feb 27, 2009 2:16 pm

Safety wire would work but it's pretty thick and stiff, IMO. Go to Michaels the womens' craft/hobby shop (or any womens' hobby shop, for that matter) in your area. They have light gauge (~24 AWG) wire for tying up flowers and that kind of thing. It's stainless and comes wound on a little cardboard form.
$2.00 will buy you enough wire to do about 100 baffles, so tell all your friends to bring theirs by.

Post by **Suzsmokeyallan** » Sat Feb 28, 2009 10:09 pm

The baffles have a lot of lower chambers that overlap, after burning them on a BBQ grill you can easily spend another hour picking out all the hidden parts of crusty carbon with a piece of stiff wire working it through the flutes etc.
Make sure you get it really clean since any carbon pieces left, only allow new deposits to stick faster to the residue.
To align them better in the pipes you can also refit the lower end into the pipe and manipulate the slender upper end for better alignment by carefully bending it so it fits and aligns freely into the pipes tube by the set screw.
Some baffles i noticed have mishapen ends and weld blobs for the cross bar on the face of the tube, a little cleaning and reshaping of this part can help it fit easier into the pipe.
Once it fits snug but not tight it will be easier to install and remove again. If the cross bars are toasted, an old Gt750 wheel spoke cut and tacked in place works great as a replacement.
If you remove the cross bar you can also repair the inner perforated tube, place a long 3/8 drive bar into the tube itself and tap on the tube to smothen out any prior dent damage to the perforated section.
You can leave it in place and using a large flat screwdriver to push the ends of the inner tube against the drive bar in the back portion to re round the tip.
Refit the new 'spoke' cross bar and tack in place once its looking all neat again.