Repairing crushed header / building a pipe

Like this

Screw the plugs into the pipe you want to fix. It's gotta be damn tight because you are going to put compressed air inside the the pipe and then heat it, which will further raise the pressure inside.

close up

What your doing is pretty cool. Also should be alot cheaper than buying a new pipe.

anybody ever seen expansion chambers made by sealing the ends of the sheetmetal design and putting 1000psi through the metal until it is round? I thought it was pretty interesting

COmpressed air - now that's a neat trick. How much pressure? I guess you're careful where to aim the pipe just in case a plug comes out.

Am thinking the dirt bike exhaust pipes may be thinner gauge metal. Some have drilled a hole in the pipe opposite dent and gradually punched out the dent. Then fill hole, grind smooth and repaint.

Some off-the-wall weird thoughts.

Have heard of but never tried filling a pipe with sand before heating and bending it to shape. Supposedly prevents pipe from kinking.

Am wondering if plugging one end and filling with sand, then heating and pounding against sand on unplugged end (improvise) might press out the dent.

Also, might try filling with water, plug both ends and freeze it.

Or fill with water before heating the dent, and allow steam pressure to do its thing. Again, being very careful where plugs are aimed during the porcess.

Could also heat pipe and apply dry ice to the dent hoping to "shrink" it out. This reportedly sometimes helps pop out automotive sheet metal body dents.

I had reasonable success using the large wood dowel method mentioned by BSKZ650. Pipe in vise with assistant keeping the dent red hot while I worked it out with the dowel.

Good Luck!

try the ball bearing trick it works awesome i've never seen anything even come close

I had a hole on an old exaust pipe from a dirt bike when I was young. I wrapped it with some heavy gauge copper wire and soldered the ends. It actually looked pretty cool and when I sold the bike two years later it was still holding strong. I bet I put 5000 miles on it that way...Russ

The discussion on plugs and the freezing water gave me another idea. What if instead of an air valve in one of the plugs you welded a 3/4” nut so a bolt could be threaded into the pipe through the nut and plug. Then, plug one end of the pipe and completely fill the pipe with water. Since water is nearly incompressible, as you screwed a bolt through the nut/plug into the water you could generate a great deal of water pressure inside the pipe which may pop out the dents. I don’t think this approach would create the pipe-bomb or air-gun hazard that might be present with high air pressure since the water won’t rapidly expand (because it was never really compressed).

timebomb33 wrote:

find a ball bearing that is just abit smaller than the inside diameter braze a chunk of wire rope to it and then pull it down to the crushed part of the pipe then heat the pipe up until it is red hot at the crushed part then pull the bearing thru it repeat on the next headers it will work very well keep the pipe red hot while your doing it.

Thanks for sharing this technique!

Wondering where these ball bearings might be found, or what type machinery or equipment they are used in.

I know the ball bearing trick works really well.Maybe next time. This seemed easy so I just wanted to try it with compressed air.

Plugging up one end and filling with water, then freezing is supposed to work too. You need a big freezer, and you'll need to check every few hours, it is not uncommon for pipes to split.

I thought about using water, it would be safer but also harder to pressurize.

Anyway, some more photos and a WARNING:

Pump air into the pipe. I put in about 30PSI. Remember you are going to heat it and the pressure will rise.

*** CAUTION***

You are now holding a loaded air gun and adding pressure. Do not aim the plugs anywhere they can cause harm, like your buddies in the shop, pets or your own face. I put a glove over the cold end and aimed it at the floor. Don't put your face right over the working area either.

IF YOU ARE WORKING ON A TWO-STROKE PIPE the oil residue can, and probably will explode once you start heating the pipe. You HAVE to thoroughly wash the pipe out first.

This is a four stroke pipe so nothing in there but carbon dust...

Use torch and get it nice and hot (notice fat dent?)

hot