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How to Rebuild Non-Rebuildable Mufflers

How to Rebuild Non-Rebuildable Mufflers

By Rick Sieman

Noisy Bike? On a Tight Budget? Read This!

Most of the bikes out there in the real world are not new machines. Not by a long shot. In actual fact, many of them are really old bikes not worth more than a few hundred bucks, tops.

This doesn't make them bad. Heck, if you washed cars and cut lawns in your neighborhood after school to save up money for your dirt bike, you ought to be proud of yourself, even if the bike was a low-bucks special.

Chances are the muffler on your bike is worn out and the bike is on the noisy side. But did you know that a worn-out muffler can seriously hurt the performance of the bike, more so on a two-stroke, than a four stroke?

However, many of the older bikes did not come with a rebuildable muffler, like most of then modern silencers on the market. And when you check out the price on a new muffler (assuming you can even find one for your older model bike), you find out that it's about one-third of what you paid for the bike in the first place.

The reason those old mufflers could not be re-packed with new sound-deadening material, is that they are riveted together, rather than held together with clips or metal screws.

Well, you can get them apart, although you have to work a bit to do it. It isn't as simple as we'd like it to be. Still, it is cheaper than buying an accessory muffler if you don't need one.

If you have the "non-repackable" blues, follow the step-by-step photos for the best way to cut down your noise quotient and get back all the power you've been missing.

And do it cheap.

1. The little things that make a muffler unrepackable are called "rivets," and you have to remove them before you can proceed. Before you get out the drill, grind away as much of the rivet head as possible, being careful to avoid grinding away any metal on the body or end cap.
2. Finish the work you started with the grinder by drilling out the body of the rivet. A 1/8-inch drill bit is what you'll usually need. This size is also common to most pop rivets, which will be used to reassemble the silencer.
3. Once all the rivets are out, you can pull off the end cap. It helps to mark a line on the silencer body to ensure putting the unit back together correctly.
4. That "stuff" I'm holding is what's left of the packing material. The outer part is hard, caked with carbon and unburnt fuel; the inside is completely blown away.
5. Lay out a sheet of packing material (fiberglass sheeting made for the purpose and available from any bike shop), lay the silencer core at one end and roll it up. Packing it very tightly will give you the best performance and longest life; loose packing will be quieter, but won't last long. Hold the rolled-up core together with a piece of tape and slide it back into the body.
6. It makes good sense to prepare the end cap by smoothing out any deformities you may have caused during disassembly. If the holes are badly gouged out, you might consider drilling new holes for reassembly, although you must be careful to put the end cap back on properly lined up with your mark.
7. When everything's lined up and finished, you can pop-rivet the muffler back together. We suggest using steel pop rivets rather than aluminum, for the sake of durability. Just make sure you choose a rivet with the proper body length. When you're done, put it back on the bike and hit the trail!