05 WR450 Baffle Questions??

[bandit99]

Ok, I did a search and am still confused. I removed the insert that goes on the exhaust end cap. 4 bolts no problem. Looking inside I can see the large wall with a couple of small pipes coming out of it. This is what I would consider the real baffle. Who has removed or modified this?

Does anyone have instructions on what and how they modified it?

What were the power gains?

Can this be modified and somehow stay under 96db?

[Dodjy]

From a previous thread:

I converted my 05 muffler with great success. It is really a work of art inside. Take off the end cap (4 cap heads) unscrew the tail pipe (4 allen screws) make up a larger rear tail pipe from a flat bit of 2mm stainless and I think I ended up using 30mm stainless tube (the hole in the end cap fits snuggly into the end of the pipe - I made up 3 tail pipes and kept getting bigger due to the amount of back pressure still present). Next take out the spark arrestor (wire mesh cage), drill out the 2 rivets in the rear end plate (where the tail pipe bolts onto) and pull out the end plate. It is tight and I used an arm from a large puller to knock it out. A slide hammer would be perfect for this. Be carefull not to deform the end plate too much. Once out you can see why the 05 muffler doesn't work real well. The gasses enter the muffler via the header which is quite big and unrestrictive, hit the far wall of the first chamber, turn around and go through about a 1 inch pipe into the second chamber, hit the wall, turn around and go through either a small pipe or very small pipe into a third chamber (I can't remember sizes but they are about 12mm and 15mm and different lengths). Then it exits through the spark arrestor and tail pipe. I removed each baffle in stages from the rear and rode the bike. I noticed more power through the whole range as I removed each baffle. I used a drill and die grinder to take out each baffle along with the pipes. I found that the noise level was still relatively quiet when the 2 smaller tubes and baffle were removed but with the front baffle and tube removed it is f'n loud. Mates riding with me reckon it's not that loud but I dissagree. It is about the same as an aftermarket straight through MX pipe. The power is awsome, so much better than with just the stock rear plug drilled out. Replace the rear end plate and rivet it in. At the moment I have kept the spark arrestor in and I plan to make up a piece of perforated pipe (same diameter as the tail pipe) to go from the header pipe to the tail pipe, then I will pack the chamber with muffler packing. This should quiet things down a bit and probably gain a little power down low to mid range due to the longer effective length of the pipe. The bike revs more freely, sounds really nice, and now pops the front wheel up in 5th with a little pull on the bars. Jetting settled on 170 main, 48 pilot, adjustable fuel screw, needle provided in the spares kit with the clip up one from center (leaner), airbox snorkel and cutouts taken out and grey wire disconnected. 14/50 gearing (stock). Total cost - 3 hours, a little scrap stainless and argon and 8 beers (2 to plan the job, 2 during execution and 4 while admiring my handy-work).

[yamageezer]

Ya know I removed mine, too much work and you end up with a loud pipe. I bought a used YZ450 pipe ($70), put a ProMoto billet end w/ a silencer ($140)and WOW. I know, more money but to me it was worth it. You increase flow which = more power.