Muffler is ripping itself apart on WR400 what's going on!!!!

Hey I have a strange problem, or at least strange to me. The tailcap on my muffler is literally ripping itself off of the bike. I rode down to mexico from Los Angeles a few weeks ago and on the way home I could hear the bike getting louder because the cap was coming off. I re-riveted it back on, and now it has ripped off again. I am tempted to just weld it on, but wanted to know if anyone else has had this problem or what the deal is?!







I've never seen anything like that before. I would be inclined to guess that there is too much backpressure for one reason or another, but that one hole really throws me off. It kind of looks like a bullet hole coming through from the other side? Heck if i know...

It's worn out. Simple as that.

It's worn out. Simple as that.

The aluminum housing will wear out over time with the heating and cooling of it from riding???

Well there you have it. It's worn out.

I guess Ill just weld it back on tonight then... will consider posting pics of the disaster by using my mig welder with aluminum spool

I tend to believe that your muffler was in desperate need of a packing job, and without the insulation to help "quell" the sonic pressure waves, they attacked and destroyed the aluminum housing from the force of them bouncing around in there. I would definately re-pack it first, otherwise it might just destroy itself again. And instead of welding it, you might be able to re-drill some new holes and pop-rivet it back together. This way you can re-pack the silencer again when it needs it. And it needs it. Maniac

ive seen this alot and worse. it started when the packing dissappeared and allowed the can and rivets to get super hot. you need to repack the can and make sure you use a layer or two of stainless steel wool first , then the four stroke packing. if you do not use the steel wool you may need to repack the can very frequently!

you will need to shorten the core the same amount that you remove from the end of the can (as you cannot reuse the previous rivet holes). Shorten the end of the can , just enough to remove the bad holes. if at all possible use new holes in the end cap as well as on the can and here is the important part DO NOT USE ALUMINUM RIVETS!! you need steel, stainless steel are the best (they are hard on your rivet gun ) they will hold up to the heat, the aluminum rivets will not. put a little high temp sealant on each rivet as you go. the thre keys are steel wool (not soap pads!!) new holes and stainless steel rivets). you will have to have other holes welded this case you may be better off getting another can off ebay, but the maintenance should be as stated above. good luck.

The aluminum housing will wear out over time with the heating and cooling of it from riding???

Not really sure why this is hard for you to understand.

As soon as the first sign of wear to one of the rivets occurs, it's all down hill from there, unless, you stop riding, fix all the rivets, re-pack the silencer correctly, and move on.

If you just keep riding on a bad part, it's not going to get better!

You have destroyed the can, and all the parts now.

I dont think you are going to be succesfull welding the stainless end cap to the aluminum housing

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