I have a '04 yfz450, sweet bike, with little mods. I have a pro-circuit T-4 exhaust and k&N filter and some body mods, that's it. My problem is I was riding yesterday about half speed, 4th gear, and the bike started bogging down. I slowed, and tried to "limp" home. 5 minutes later, in second gear, going approx. 5 mph, the side of my exhaust blew out. I mean, it looks like this thing had a bullet go through the side of it. There is a huge gaping hole in my exhaust. Now my thinking tells me that something blocked the exhaust, that's the first thing you will ask, but I was riding on dry rock road, no jumping, no wheelies, no water, no nothing.

Could the baffles come loose in the pipe and clogged it? Is this a manufacturer's defect? Will they take the pipe back? WHAT THE HELL

HELP

 

I never heard of anything at all like that before. It seems very very unlikely to me that the motor could possibly create enough pressure in the exhaust to rupture it if it was blocked. I think the motor would shut off before there could be enough pressure inside that exhaust to cause it to rupture. It sounds more likely to me that you ran over something that got kicked up, then got jammed into the exhaust, kinda like a pole vault. Or maybe some hunter thought you were a deer and took a shot at you.

 

Did you re-jet your carb? I know those quads came through factory lean, and if you put a pipe on it without re-jetting it it's probably way lean. This would make the exhaust extremely hot and if your exhaust was restricted by melted baffles or some other obstruction maybe when it got real hot it turned to butter and blew out. I guess even if you did re-jet and made it too rich it may clog up your exhaust, but I don't think it would get hot enough to blow out. Where did it blow out, can or head pipe?