I finally got my 400 running right, after rebuilding the carb. Now the problem is something in the muffler keeps falling. It seems like the baffle falls down or is loose. When it happens you can hear the difference in the sound, it sounds alot like a jet plane. And the power is all but gone. A quick (and pissed off) kick to the muffler and it seems to line back up and run OK, untill I hit full throttle. It doesn't seem to like that much pressure on it. This of course happened deep in a trail ride and I had to baby it all the way back home. With the price of a new stock muffler at about $300 and unable to locate a used one in my area. I was wondering if it was possible to repair it. Other then that it looks like I would have to go with an aftermarket muffler and rejet the carb.

 

you could try removing the baffle ( wich may require jetting) and depending on how rusty the exaust is ..you may be able to find some one to cut it open. re weld the baffle ,then reweld the muffler back toghether ( id try a welding shop or someone with a mig welder ....sounds to me like the baffle is roling around and occasonaly blocking off the exaust
( you can buy a nice mig welder from lowes for about $300.00 and fix it yourself )
they have cheaper ones but the expensive on is more versatile it will weld the thin exaust and thicker metal like frame parts up to about 1/4" thick
a handy tool to add to your shop

 

Thanks, I was hoping that was possible. Yeah one of the guys here at work has a mig welder, so I will be pulling the muffler off tonight when I get home.

Thanks again, I'll let you know how it turns out.