Repacking a WR 450 Silencer

I wouldn't bother if you haven't already gone through this. Sat through some Youtube video on the repacking process and then went to work. Disassembly involves having to drill out some rivets as well as remove some hex headed screws, ended up with something entirely different than I had seen on the videos. This WR Silencer is a hollow perforated core, with 3 internal chambers, taking up about 4/5th of the cavity, not simply a tube, one offset tube in the front section of the chamber about 3/4 dia. of mid pipe runs into the center chamber,from there 2 different diameter tubes dump into the rearmost chamber. The insulation or packing is probably only 3/4 of an inch and wraps the core. So most of the silencer is air space. About 1/3 of the insulation was gone burned up I'm guessing. I didn't really want to spend the money on an aftermarket, but I'm not real impressed with this design. Beginning to see why so many go with the aftermarkets.

Just went on the WR250F Forum and found some more data, some have modified the baffles and evidently doesn't require disassembly, at least pulling the muffler core. The core does have to be removed to repack the core, and yes it does need repacking from time to time. They evidently have opened up the second baffle, plate by drilling an additional 16-24 mm hole and seem to be pleased with the results. I'm going to repack and perform this on my 05WR450 silencer and see what happens before picking up a replacement.

I did this to my muffler and the difference is night and day. I removed the whole end piece (minus the outter end cap which is just for looks so I left that) and drilled three half inch holes through the inner baffle chambers. I suggest drilling one hole then test, then another and test etc. This way you can find the perfect compromise between sound and performance. I just drilled all three then tested. It's amazing, but a little louder than I like. I think I would have preferred two half inch holes. I am still around 97 db so it doesn't make my ears bleed or anything, just kinda loud for all day rides. If you want a straight through muffler just cut all the inner baffle walls completely out since you have the muffler open anyways. This will probably make it in the low hundreds as far as decibels goes, but the performance should be awesome. Just all depends on what you want.

My '06 WR has all of the sound baffles removed, which makes it a straight thru open chamber. With the stock small exhaust tip in the end, it runs right at 92db's. I just sound tested it this weekend, and that' with the still stock packing. Maniac

Well after thinking about it, I decide to try and go ahead and repack the silencer. I also drilled a third hole in the backmost baffle, about 16mm. I used some wrap for a Lexx silencer, just went with one layer, but it was a real battle, took both ends out and ended up stuffing ribbons of packing from the end opposite from the installation end, as the material just wouldn't go in with the core even though I fed it with a butter knife. Did the best job I could, but like I said earlier, I'm not sure I want to tackle this project again, cam replacement, carb work, would be easier.

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