'00 WR400 Stock Cdn Exhaust Packing

I have the stock Canadian exhaust on my '00 WR400 and it just keeps getting louder and louder. It has a fairly satisfying exhaust note now compared to when I first got it and seems to be progressively developing more power - believe it or not. Definetly more pull, front wheel is in the air more, and hitting the rev limiter more ferquently. The exhaust is now loud enough that my ears are ringing a bit after a ride. My theory is the packing is wearing out or blowing out, but I have no evidence of that. Last year I rode with a guy who had the exact same bike as me and he couldnt believe how mine sounded.

Does anyone agree with my packing theory or have any ideas as to why I seem to be progressively developing more power. A great problem to have I guess :)

:) Bit difficult to comment ont Canadian Variety, the stock Euro dustbin mine came with doesnt have packing just a load of baffles and chambers, if it does have packing then it could be blowing out, certainly you have to maintain YZ and other straight thru type cans,

Actually, now I vaguely recall a post that described the internals of the Cdn pipe, and there may not be any packing in it, just baffles. Why it seems to be getting much louder but throatier sounding as time goes on and pulling 4th gear wheelies easier than before is beyond me.

I have the Australian wr400-99 & I belive it has the same muffler as the Canadian bike. I have cut the end off & made a new end cap for it. From 22mm to 40mm. There is no packing inside these mufflers only baffles.

Now the bike performs much better. Lifts the front everywhere.

I've followed Taffy's jetting advise & I couldn't be happier with the bike.

Maybe you have an exhaust leak somewhere which is letting out gas & noise.

BillS, the Canadian pipe has no packing in it. The pipe is a true muffler like on your car, the exhaust travels back and forth in the muffler through progressively smaller pipes until it hits the exit. Do a search on it and you will find a cutaway drawing of the Canadian/Euro muffler for the WR and also of the U.S. WR and one of all YZ's. Your muffler may be getting louder from rusting out inside, if you don't start the bike after washing it, to blow out and dry up any water that gets in.

[ April 28, 2002: Message edited by: WR Dave ]

So it must be rust then, although I cork the end while washing and always start it up for 5-10 mins afterward. Maybe trailering home in the rain a few times and not starting it afterward could have caused rusting. For the future I have a stock US pipe as well that I will install a vortip or something similar into in but for now I'm happy with the way it's running and sounding.

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