How To Repack a 2 Stroke Dirt Bike Muffler (Silencer, Exhaust)


In this post I’ll be showing you how to repack the silencer on a two-stroke dirtbike. Silencers are designed to do just that. Silencer quiet down the sounds that are coming from the exhaust to an acceptable level.

Now the silencer packing which is made of fiber glass, not only does it dampen the sounds but it also collects carbon deposits that are coming from the exhaust. Then after a period of time and use, the silencer will collect so much carbon that it will no longer be able to serve the purpose that it was designed and intended for and will eventually need to be replaced. Now an easy way to tell when it’s time to replace the packing in your silencer, is your bike will start to become noticeably louder. f

So today we’re going to show you how to replace the silencer packing on a Yamaha YZ250 two-stroke. To do this job, you will want to have some basic hand tools as well as a rubber mallet, some scissors, masking tape, some contact cleaner, some rags, rubber gloves and safety glasses as well as a wire brush, some high temp silicone gasket sealer and some medium strength lock type.

Now you also want to pick up some replacement muffler packing, we do offer many options for you to choose on our website so be sure to check that out. But for today, we’re going to be using the Lexx two-stroke silencer packing. And as always before doing any work on your bike, always make sure to reference the service manual for safety information, proper procedures and torque specs. To begin, start by removing the silencer.

To start, we’re going to disassemble the silencer. Now some are going to have fasteners and or rivet. They’ll either disassemble at the inlet side of the silencer or the outlet side. But when it comes to your specific exhaust, you want to reference either your service manual or the manufacturer of the silencer for those specific details. Alright, so once you’ve got your fasteners removed, this is where we’ll need to be able to put out the core of the silencer.

Now this may be a little bit difficult to do depending on your exhaust, so this is where your rubber mounts going to come in handy. So I’m just going to hold on to the exhaust like so and begin to work the silencer off. Then we can pull the core out, now we can pull out the packing inside.

Now for this silencer, this is as far as we will be disassembling it, this is the FMF Turbine Core2 and they do not recommend that we disassemble the outlet side. So now that we’ve got this apart, we can clean up our core with our wire brush and some contact cleaner. Now right here on the section of the exhaust that goes inside of the silencer, there’s usually going to be some silicone.

You want to make sure that you get all that removed. So after you’ve cleaned the side with the core, you want to make sure that you clean the, this side of your silencer to make sure again that you remove all the silicone. You may even want to take a rag, spray some contact cleaner on it and then just try to wipe out all the old carbon from inside of your silencer.

Now you also want to look down inside if there’s any left over, fiberglass, you want to make sure that you can reach in and remove it. Alright, so once we’ve got all our parts cleaned, we’ve got out the old carbon scrubbed off and removed, we can set these aside. Now we’re going to open our new packing, unroll it. Now keep in mind that you are going to be handling fiberglass.

So it’s very important that you are wearing rubber gloves and it may not even be a bad idea to wear painter’s mask when you’re handling this material. Now, the Lexx two-stroke silencer exhaust packing is a universal exhaust packing so when we are measuring it, we need to cut it to size, we’re going to take the core from our silencer, we’re going to line it up with the edge of our packing right here and this is going to let us know where we need to cut it.

Alright, so once we have our section of packing cut to the right length before we begin wrapping the silencer’s core, we need to take some masking tape. We’re going to cut some long thin sections so that way once we got this all rolled up, we can grab the tape and secure it to the core. Now as you can see as I’m lining up the edge of the inlet side of the core right here, it’s just going to butt up against it and we’ve got some little left over.

So I’ve compensated for the recessed section inside of the end piece here, so that’s why we are at this length. Now once we get it all rolled up, we’ll be able to stuff it into this end of the core. And when you’re packing this, make sure that you get it pack in there nice and tight.

Alright, so once we get to there, we’re going to take a strip of our tape. So this is going to help us keep the packing that we just rolled nice and tight. Alright, now we need to begin working this end of the silencer’s packing into the inlet side. Alright now we’re going to install the wrapped core into our silencer. Now before we get this installed, keep in mind that when you are inserting this in there, you want to make sure that you have the orientation of the core set correctly.

 Now if you were to do it, set it in there upside down, you’re going to have some problems when you go to mount up your silencer to your head pipe later so just be aware of that. Now as you’re putting it together and getting this last section of it fitted into the silencer, you want to make sure, take your time be careful. You want to ensure that the tip of the core is going to me making it into the other end of our silencer here.

Just before we’re able to slip it into the last section that it needs to go, we’re going to take some of our high temp silicone gasket sealer, we’re going to coat this seal right here this edge and then we can finish putting it together. Now we really don’t need to use a whole lot right here, just enough to create a seal.

Wipe off the excess sealant then we can take our fasteners, we’re going to clean these up just a little bit to get any old carbon off. Spray them off with some contact cleaner. Alright, now we before we install our fasteners to secure the inlet side into our silencer, we’re going to apply some medium strength thread locker.

Now I’m installing all of these loosely in case there’s any last little minute adjustments or shifting that needs to take place, then once we have all of our fasteners installed, we can go ahead and snug them down. And that’s it. That’s all there is to when it comes to replacing your silencer’s packing. Now I’d recommend that you’re replacing this about once a year or once every riding season so that way you can get the most out of your silencer’s performance.

Now another quick tip is to plug your silencer every time that you wash it that way, you can keep the water from getting inside of it and then you get the most out of your freshly packed silencer.

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