exaust problems with 4 stroke sato 100
 

I have a Sato 100 and have had a lot of problems with the exaust system. My latest problem is with a flex muffler. It broke off near the head. I turned it around and connected the other end to the head. It lasted thru the first flight and then broke off and was lost during the second flight. These things cost 48.00 inc s &h. I don't know what to do. Any suggestions?