Re: New here, with a DIY Chainsaw Bike
Here's the latest: I made a new header from plate steel to replace the soup can properly. It's the first welding I've done in ten years, so it's far from a pretty bead; but strong and functional. Same steel as the muffler cap, welded together with it. The open end is bolted through the spark arrestor holes on the exhaust flange from the motor. It's a slightly longer rectangular chamber, as opposed to the short wide style of the old. The volume/capacity is similar, and it clears the tire well.
I noticed an improvement of at least 2mph on top end and less 4-stroking at low throttle on the test run. It only chugs when starting now, and "gets the flow" much sooner on takeoff.
Between the miles ridden and the goose chase it endured around town in the trunk, that can never stood a chance. I couldn't see the hole in the underside at all until I removed it to mount the new header. Glad I had something at the ready to replace it. Can't claim to have planned it out that way.
Now that I've started welding again, I'm ready for anything. Once I get some more practice in to get the feel back, the fun will be endless.