Repacking A Silencer

I got some FMF 2 Stroke Performance Muffler Packing. One bag this size can do 2 silencers the size of my MRP.

Sorry, but I didn't take any pictures of the repacking process. A friend came over as I started working in it and I got distracted from the how-to pics. Here's a brief how-to for anyone interested in repacking their aftermarket pipe though. This process may vary slightly with different aftermarket pipes, mine is the MRP 70cc Minarelli pipe.

If equipped, remove the bolt securing the outlet end of the silencer to the bracket welded to the expansion chamber of the pipe.

Remove the 3 nuts attaching the inlet of the silencer to the pipe's flange. Mine require a 10mm wrench or socket.

Remove the silencer and take notice of the exhaust gasket between the flange and silencer. It will often stick to the silencer or flange. If it doesn't come off easily, inspect it's condition. If it is damaged, you will probably want to scrape it off and clean the surfaces so you can use a fresh gasket or a sealant later. If it is in good condition, you may wish to leave it where it is so you can reuse it.

There should be 3 studs sticking out of the silencer's inlet end. Gently tap those out with a soft rubber mallet, trying to remove them evenly until none of them are protruding from the silencer's casing.

Grab the outlet end of the silencer, and you should now be able to pull it free from the case.

Remove all of the old packing material, and clean the metal core of the silencer. I used brake parts cleaner. If your silencer is gunked up, you may need to use botha chemical cleaner and a hard bristled brush.

Now it's time to repack the silencer with new material. Some people like to wrap an initial layer of steel wool around the core of the silencer and then finish wrapping with a packing material. I chose to go with only the FMF packing material. You want to wrap it well, but not too well. Packing a silencer too tight can actually make it louder and/or reduce performance. If necessary, you can wrap a small bit of masking tape around the ends of the material to keep it in place. I did not need it.

Now you need to insert the core back into the case. Start pushing the core back in and use a screwdriver or other tool to coerce the packing along. If you haven't over-packed the core, this shouldn't be too difficult.

Once the core is nearly all the way back in, you will need to put a light coating of copper RTV sealant around the lip of the core to help seal the core and case together. Once coated, finish pushing the core in, being sure to line the studs on the inlet side of the silencer up with their holes in the casing. It may be necessary to lightly tap the silencer with a soft rubber mallet to get it completely into the case.

Use either copper RTV, a new gasket, or the old gasket if it is in good condition and attach the silencer to the pipe again. Tighten the nuts to secure the silencer.

Reinstall the bracket to the outlet end of the silencer.

I was actaully very suprised with the results of repacking with FMF's material. My MRP pipe has been loud since it was brand new, and extremely loud lately. I expected it to go back to being just loud. It is actually much more tame than it has ever been, but still sounds good. I am pleased with the results and gladly recommend FMF's product to other 2 stroke owners.