I just bought a downswept expansion chamber for my rougher of the two JTs. Unknown manufacturer. I’ve been wanting to find a downswept pipe for any one of my bikes and they are just hard to find. So now all my little ones will have the crispy crackle. 

imgur.com/a/3eejUjs
 

Schu they look great

Well I've bought 8 expansion chambers for my enduros and this downswept is the first one that didn’t fit as advertised. The seller will take it back for full credit because he claims to have gotten the pipe from a Yamaha dealer that closed up, and the pipe was marked for a JT.

But I really like the pipe so I have chosen to keep it and do some creative fabrication. The center mounting bracket attaches properly to the right side engine cradle bolt. And the back half of the pipe lays in nicely and leaves just enough clearance to the rear tire.

However the connection at the cylinder is way off. It makes me wonder if this pipe was made to fit a performance cylinder and head combo. I know Webco sold performance heads, but I am not aware of any aftermarket performance cylinders that may have had a different exhaust outlet.

I will probably have our incredibly talented sheet metal fabricator at work do the modifications. My son is a pretty good welder and has various types of welders. But I had asked him to tack weld a nut to the body of a Bassani pipe and he accidentally blew a hole thru the metal. It was surprisingly easy to do. He then brazed the nut and filled the hole.

I finally got around to installing the modified downswept pipe on my old yellow JT.  It fits well now after he reshaped the front portion of the pipe with 3 cuts/welds. I did have to use an offset kick starter and I had to reshape the rear brake lever. But it has the satisfying little crackle sound that I love so much on these old 2-strokes.

Nice job!!

Great Job love that sound.  

Now, if only you could get rice crispies to crackle like that! (: