I was wondering if anyone has repaired an expansion chamber using heat(torch) and compressed air to remove dents. I realize this is something that could get very dangerous. Is 1 or 2 psi enough pressure? What would be the best mechanism for plugging the two openings? Is a mapp gas torch enough heat or is an Oxy-acetylene set up required? Any advice, direction or horror stories of what went wrong would be greatly appreciated.
Exhaust Repair
- Thread starter iajim
- Start date
FYI - It isn't that expensive to send it to pacific crest pipe repair and have it professionally done.
www.piperepair.com
Others using the expansion of freezing water to pop out dents - e.g. fill it partially with water - plug the ends (plumbing fittings) and throw it in the freezer...
jeff
.
www.piperepair.com
Others using the expansion of freezing water to pop out dents - e.g. fill it partially with water - plug the ends (plumbing fittings) and throw it in the freezer...
jeff
.
HuskyDude
Super Moderator
Those picture on the Pacific Crest site are amazing.
I've done the PSI and torch thing. It was with a acetylene touch only for soldering pipe. Propane will work too but you need a big tip. It happens pretty quick so less psi the better. These were for small dents nothing like those pictures...
I've also heard of riders using water then place your expansion pipe in the freezer. Water expands into ice...etc. Again for smaller dents.
I've done the PSI and torch thing. It was with a acetylene touch only for soldering pipe. Propane will work too but you need a big tip. It happens pretty quick so less psi the better. These were for small dents nothing like those pictures...
I've also heard of riders using water then place your expansion pipe in the freezer. Water expands into ice...etc. Again for smaller dents.
eddy field1
New member
ive done this before using a propane torch and had to use almost 50 psi!! but the ideal pressure is ment to be around 20-30 psi this should be fine with oxyacetylene as it will obviously get it alot hotter. My friend has even gone as high as 100 psi glad i wasn't there!!!! his pipe dint explode so you should be ok but i would say 1,2 psi probebley wont do it
I think the water thing is for 4st pipes as it can crack the welds on a 2st
I think the water thing is for 4st pipes as it can crack the welds on a 2st
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stainlesscycle
Site Sponsor
the water thing has issues - if you fill a pipe up with water and freeze it, it will expand all over evenly (or at the metals weakest spot...) not just at the ding. there's a chance that it will actually work, but there's a chance you'll end up with a misshapen pipe... pacific crest pipe repair is cheap...
Warning!! you have to either clean the inside of the pipe very well or use an inert gas!! I do this repair on occasion and I use argon to pressurize the pipes,, using regular air you can have a bomb.. the residue from the 2stroke fuel can heat up and catch fire or actually blow.. had a pipe blow the plug across the shop and shot a flame 10 feet.. the guy that was helping me had no hair left on his arm and some of one eyebrow singed.. If you dont have argon soak the pipe with a simple green or similar and wash out good.. If you know someone at a machine shop have it hot tanked then no worries..
I've done this a couple times with pretty good results.
I use regular compressed air and mapp gas torch. I heated the pipe up real well in the dented areas with the pipe open to burn off any fumes. Then washed it out with degreaser and water a couple times.
Low psi did nothing in my case. I actually had the thing up over 100 psi after adding heat. I shot out a 8 ft. fluorescent tube when the expansion plug blew out of the small end but that was because I didn't clean the spooge out very well before hand. Second try I cleaned up the end and the plug well with acetone and made sure she was aimed at something less fragile. It held over 100 psi.
After that experience I'd personally would feel plenty safe at 50 - 60 psi but YMMV. For sure try more heat at lower pressure first. Maybe a bigger torch applying heat over a larger area would be safer and more effective, but the mapp gas will get a pretty good sized area cherry red. Maybe I was impatient and things might have moved at a lower pressure. Most Google "articles" seem to suggest that lower pressures are effective.
You can get rubber expansion plugs to fit the small end at any hardware store. I made a pressurizing clamp/plug for the big end out of a schrader valve test fitting (also from the hardware store), a pressure guage and some 1/4" plate. If you Google 2 Stroke pipe repair you should find pics of various contraptions that can be cobbled together.
I use regular compressed air and mapp gas torch. I heated the pipe up real well in the dented areas with the pipe open to burn off any fumes. Then washed it out with degreaser and water a couple times.
Low psi did nothing in my case. I actually had the thing up over 100 psi after adding heat. I shot out a 8 ft. fluorescent tube when the expansion plug blew out of the small end but that was because I didn't clean the spooge out very well before hand. Second try I cleaned up the end and the plug well with acetone and made sure she was aimed at something less fragile. It held over 100 psi.
After that experience I'd personally would feel plenty safe at 50 - 60 psi but YMMV. For sure try more heat at lower pressure first. Maybe a bigger torch applying heat over a larger area would be safer and more effective, but the mapp gas will get a pretty good sized area cherry red. Maybe I was impatient and things might have moved at a lower pressure. Most Google "articles" seem to suggest that lower pressures are effective.
You can get rubber expansion plugs to fit the small end at any hardware store. I made a pressurizing clamp/plug for the big end out of a schrader valve test fitting (also from the hardware store), a pressure guage and some 1/4" plate. If you Google 2 Stroke pipe repair you should find pics of various contraptions that can be cobbled together.
iancp5
New member
I've done this as well. Needed more like 60 - 80 psi not 1 or 2!
It shouldn't be too dangerous. If it blows I would expect it to just split not fire bits of metal about (I didn't have an expansion plug on mine whatever that is). I used a MAPP gas torch. Propane wasn't hot enough. Oxy is probably too hot and too localised. You need to get it pretty hot though at least cherry red.
It shouldn't be too dangerous. If it blows I would expect it to just split not fire bits of metal about (I didn't have an expansion plug on mine whatever that is). I used a MAPP gas torch. Propane wasn't hot enough. Oxy is probably too hot and too localised. You need to get it pretty hot though at least cherry red.
I had good luck freezing the dents out of mine. Filled it with water capped the ends with rubber gloves and froze it. If you don't keep a close eye on this method I could see where it would split your pipe right open. It took all day for it to freeze and in the end it didn't remove kinks just dents.
I have used the freezing method a number of times...
Advantages:
safe
easy
low cost
Disadvantages:
need enough freezer room
need to watch it so it doesn't go too far and split pipe (range 8 to 13 hours for me)
does not remove the small dents very well
does not remove kinks (but neither does Pacific Crest Pipe Repair)
Advantages:
safe
easy
low cost
Disadvantages:
need enough freezer room
need to watch it so it doesn't go too far and split pipe (range 8 to 13 hours for me)
does not remove the small dents very well
does not remove kinks (but neither does Pacific Crest Pipe Repair)
Oxy/acc is good with a rosebud,, but mapp is easier if your not used to working with torches.. and I use 50-60 psi.. I dont wash out too well but I use inert gas so I dont have to,, no oxygen in and it cant burn,, kinda like halon onto a fire.. if you get up to 100psi or more the plugs can pop out at a high rate,, if the residue lights the pressure inside goes up quick which is what I had happen before I went to argon.. I have a mig so that gas is right there.. I made a fitting from an old regulator so I can fill the pipe to 80psi with argon. it walks down to 60-50 before I top it off again... easy and safe.. I have enough smells getting into my icecream dont need to add 2stroke exhaust to it.. although with the current temps outside I think its colder out there..
lvermey
New member
Pipe repair.
I made my own repair kit, and have fixed a bunch of friends pipes. Some were real bad. Two were kinked at narrow section just before the expansion chamber. They both ended up cracking as I straightended them. I just kept tig welding the hole whith stainless rod. I worked out real well.
I used those frost plugs at first, but under 80 psi or so they blew out a few times. Not the most fun experience. But it was always the manifold end, not the stinger. So I went back to the drawing board. I took a piece of 2" pipe, threaded three bolts spaced evenlly around the circle. Then welded on three nuts spaced evenlly between the bolts. Then took a square piece of 1/4" plate, drilled holes that lined up with the nuts on the collar so bolts could secure it on once the collar was secured. Glued a piece heavy truck tire tube on the sealing side. Drilled and tapped a hole in the middle to accept the fittings I needed, along with a preasure gage, and a small ball valve in front of that so I have good control of my air supply. I drilled and tapped the stinger frost plug, and put a shrader valve on that end to relieve the preasure in a friendly manner. No more flying projectiles in my shop!
I used to use mapp gas, but you can't get the area of a large dent evenly heated. I now have a oxy / acct rig which works far better, faster. I just use a large gage brazing tip, and keep it moving. Washing the pipe out with water is a good idea. I have never had any thing blow from cumbustion. On average, the psi required is 20 to 40. I have used to much and the dent became convex. Had to heat it and use cold water on a rag to shrink the metal and get it back in shape. I made the rig just from scraps laying around the shop. Tig is the only way to weld pipes because they are so thin. One thing I missed. You can use less air psi if you heat the dent, up only 20psi say, and when its red hot, tapp around the outside edge of the dent and this will help it to start the centre moving out. Hope this helps some people out.
I'm getting so good, I think I will start charging
I could take a few pics if anyone is interested in making their own.
I made my own repair kit, and have fixed a bunch of friends pipes. Some were real bad. Two were kinked at narrow section just before the expansion chamber. They both ended up cracking as I straightended them. I just kept tig welding the hole whith stainless rod. I worked out real well.
I used those frost plugs at first, but under 80 psi or so they blew out a few times. Not the most fun experience. But it was always the manifold end, not the stinger. So I went back to the drawing board. I took a piece of 2" pipe, threaded three bolts spaced evenlly around the circle. Then welded on three nuts spaced evenlly between the bolts. Then took a square piece of 1/4" plate, drilled holes that lined up with the nuts on the collar so bolts could secure it on once the collar was secured. Glued a piece heavy truck tire tube on the sealing side. Drilled and tapped a hole in the middle to accept the fittings I needed, along with a preasure gage, and a small ball valve in front of that so I have good control of my air supply. I drilled and tapped the stinger frost plug, and put a shrader valve on that end to relieve the preasure in a friendly manner. No more flying projectiles in my shop!
I used to use mapp gas, but you can't get the area of a large dent evenly heated. I now have a oxy / acct rig which works far better, faster. I just use a large gage brazing tip, and keep it moving. Washing the pipe out with water is a good idea. I have never had any thing blow from cumbustion. On average, the psi required is 20 to 40. I have used to much and the dent became convex. Had to heat it and use cold water on a rag to shrink the metal and get it back in shape. I made the rig just from scraps laying around the shop. Tig is the only way to weld pipes because they are so thin. One thing I missed. You can use less air psi if you heat the dent, up only 20psi say, and when its red hot, tapp around the outside edge of the dent and this will help it to start the centre moving out. Hope this helps some people out.
I'm getting so good, I think I will start charging
I could take a few pics if anyone is interested in making their own.
redrider7202
New member
please post some picks.
lvermey
New member
I will redrider. Just give me a few days. Just finishing my last night shift, and wouldn't you know it. My wife comes home from work, and the Montana van is making a funny noise. So I am going to have to look into that first thing
I was going to put my new piston in my o8 EC 300. Parts arrived on Monday. The winter here in BC has been so mild, my buddies have been riding the past two weekends in the lower elevations!
I will post them, and you will see how simple it is.
I was going to put my new piston in my o8 EC 300. Parts arrived on Monday. The winter here in BC has been so mild, my buddies have been riding the past two weekends in the lower elevations! I will post them, and you will see how simple it is.
stay_upright
New member
Does anyone have pics of - or can comment how good the finished 'amatuer' article is. I've done this and the result was rather bobbly and ugly though functional... Also scared the cr*p out of me when the dent popped out.............BANG!