Difference between YZ & WR450 exhaust?
Posted November 07, 2003 - 07:22 PM
Am I going to have to upgrade the stock pipe on the WR?
Posted November 07, 2003 - 09:42 PM
Posted November 08, 2003 - 10:41 AM
The airbox mods, Pipe and jetting made an incredible difference. At least 10 hp I would estimate.
In fact the bike literally would not run with stock jetting after letting her breathe.
My friend flipped his yz over backwards and the first thing to dig into the ground was his pipe , which bent the subframe, cracked the airbox and squashed his pipe in one single expensive little loop out.
I looked at my yz pipe and decided since I got it real cheap, that I would cut 6" off the end of the can and cut the same amount off the core. I also ground down the diameter of the bolt holding the can to the frame. In essence creating a threaded shear pin, so if the pipe dug in it would break without damage to the subframe and airbox. Now my pipe only sticks out about 2" past the end of the # plate.
The shorter pipe gave my bike yet more throttle reponse and more power everywhere. I had to go up one size on the main jet as it ran a little lean with the previous 168 main.
I know it sounds like a backyard mod, and not very scientific but I wanted to try it out.
Pipe builders will think or say I'm an idiot but they earn a living selling pipes. Of course they will doubt this mod.
Hey, it worked for me and I saved $600 cause my pipe cost me $200, and it does not stick out like a ancor waiting do to $hundreds of damage.
Definitly the pipe will make a difference in power but it will be louder too. So if you have to pass dB regulations it will not work so well in that respect.