Tuesday Tip: Get Packing¿Four-Stroke Silencer Repacking With Team Rockstar/Suzuki’s Ed Longacre
Intro» Ryan Cooley // Photos» Garth Milan
You may not realize it, but silencer maintenance plays an important role in the overall performance of your bike. And with four-strokes dominating across the globe, we thought it was about time to address the proper way to repack your four-stroke’s silencer. Four-stroke silencers are similar in design to two-strokes, but they differ in the type and amount of abuse they take. A two-stroke silencer typically becomes noisy with wear because the packing gets saturated with excess oil that passes through the exhaust gasses. The unburned oil turns the packing soggy, deteriorating it quickly. Four-strokes, on the other hand, are subjected to much higher temperatures at the silencer, and thus the packing literally burns and blows out. Yep, every time you ride, you leave a little bit of your silencer packing at the track or floating in the atmosphere, and with each deposit, performance is lost.
So, if your four-stroke is offensively loud or lacking that snap that it used to have, it’s time to get packing! Team Rockstar/Suzuki’s Ed Longacre shows you how he keeps Ryan Mills’ silencer functioning quietly and at peak performance.
REQUIRED TOOLS: Silencer packing (four-stroke type), T-handles/sockets (silencer removal), drill and bits (drill out rivets if needed), Allen wrenches (end cap removal), pliers (pull core from canister), high temp silicone (seal end cap).
STEP 1: LIFE SPAN
A good rule of thumb to follow with four-stroke silencers is to replace the packing after every seven to 10 hours of riding. If you aren’t sure how much time you have on your packing, however, there is an easy way to check its condition by simply knocking on the outside of the canister. Does it sound hollow? If it does, it’s probably time to repack it. Ideally, you should hear some type of a thud indicating that it’s full of packing. Another telltale sign that the packing has been blown out is cracking around the end piece on the motor end. Without the proper amount of packing, excess heat may actually fatigue the metal to the point of cracking at the welds.
STEP 2: DISASSEMBLY
Remove the silencer and examine the end cap. If it is riveted, the rivets need to be drilled out. Find a drill bit that will drill the head of the rivet off without over-sizing the original hole. Drill all rivet heads off and use a punch to knock the rivets all the way through. If your end cap is held on by bolts, simply remove the bolts and pop the end cap off. If the end cap is difficult to remove thanks to the hardening of the silicone sealant that was originally put on, apply heat around the end of the canister, and it should pop right out.
With the end cap removed, you will now see the remains of the old packing wrapped around the core. Use a pair of pliers to pull the core out of the canister. Most aftermarket silencers are designed so the core can be pulled out of the can. If you have the original exhaust system on your bike, refer to the owner’s manual for disassembly instructions. Discard the old packing and inspect the core for cracks or clogging. Clean or repair if necessary.
STEP 3: PACKING
Arrange the new packing so that one end’s width is approximately as wide as the core. The length of the packing should be enough to wrap around the core about three to four times. Wrap the core snug, but not too tight. If the core is wrapped too tight it will actually increase the noise level. The firmness of the final packing should feel like that of a firm pillow. Four-stroke packing is usually stringy, so try to keep the packing as uniform as possible. Once you’ve wrapped the core properly, you can secure the packing with some masking tape to keep it from unraveling.
STEP 4: ASSEMBLY
Feed the core and packing into thee canister as a unit, but do not allow the packing to bunch up at the end. When you get the core/packing about halfway installed, use an 8mm T-handle to push in the remainder evenly. When the core/packing reach the end of the canister, ensure that the core is engaged into the end piece. This may take some patience, but you will feel it click over the internal tube. If there is space left to be filled within the canister, add a few more strands of packing. Before reinstalling the end cap, place a bead of high-temp silicone sealant around the end cap mating surface to prevent water from deteriorating the packing while washing. After making sure that the core has engaged into the end cap’s tube, rivet the end piece or install the bolts as necessary. Install the silencer back onto the bike, and double check all fasteners.