RE: LOOKING FOR YS61SF(TWO STROKE) MUFFLER
I would give Jett Engineering a call, or Performance Specialties (Ultrathrust). See if they have a muffler that will work, which I am sure they will, and an adaptor. In fact, I'm thinking of doing the same thing myself. I have a YS.60 side exhaust ready to go into a Dirty Birdy.
Ed Cregger