2 stroke pipe repair

I've heard that you can pressurize a 2-stroke pipe and heat up the dents with a torch and they'll blow back out.  Sounds pretty neat to me so finally I made some fittings and gave it a shot. I put a gigantic dent in my FMF pipe up at Walker Valley. This thing was huge, it actually cracked the factory weld of the pipe, about 1" long. I rewelded it and ground it down a bit before heating. This dent was about 3" in diameter and about an inch deep. Since the pipe was basically destroyed it seemed like a good test pipe to see if I could make this work.

I used 1/8" pipe through a rubber stopper on the silencer end, I welded up a flange that I could clamp this thing into the pipe with. I started out with a gauge that read from 0-20 psi thinking this would give me better control over the pressure.







This is also a rubber stopper that I drilled a hole through and pushed through part of a bicycle stem/valve that I cut out of an old bike tube. It worked great for regulating the pressure in the pipe as I heated it

Turns out 50-60 psi works best with a nice dull-orange color. I just used MAPP gas in a handheld torch.

The small rock dings before the expansion chamber are tough to get. I tried but they wouldn't quite go, maybe with a smaller torch.  Not bad considering these pipes are $250!