I made a silencer a few years ago for my Hybrid Engineering 310. I learned a few things in the process that I put to use on the silencer for the 391cc engine that Pete put together for me. The first thing I learned was the core should not be welded to the stinger or the end cap.
Second thing is the stinger and turn down bot should be welded to a "flange" that bolts to the end caps.
Third is that both ends should be removable and have "O"rings.
Fourth thing I learned is to machine a collar/sleeve for the stinger to head pipe connection instead of trying to expand the tube.
The first picture shows me machining 3/8" off the outer diameter of a piece of 4" ID aluminum conduit for the silencer body
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The next picture shows a finished end cap with the perforated core. I forgot to take a picture while machining it sorry
Then we have a picture of the silencer mocked up with both ends and the turn down....
Now this all took place months ago before I had the big motor done. I got the 391 and installed right before my last trip. I didn't have time to finish the silencer and went with the trx5 pipe and my first homemade silencer. Now fast forward to last Friday.... I decided that I must have the CPI pipe I acquired and the silencer on my R before the 250R Winchester bay meet!
So I buckled down and got it done...