Pipe Fix

joe28kdx · Apr 8, 2002

So there I was laying out my sons and my new Hare Scramble course and I look over and my KDX200 descides to lay down. When I pick it up there's a nice dent in the pipe right where it comes out of the head.
I've read about fixing them with a torch and air PSI but, have been lucky never to have had to do it,(thank God for pipe guards!)
I got a soft plug with rubber and a tighting bolt for the head side, a small press in one that I drilled a hole and installed a stem to add air.
Safety came in the way of a piece of strap with a hole over the air valve and 2 long bolts through it, held fast to the pipe with 2 hose clamps. The rubber soft plug was held in place with a small chain X over it secured to the spring loops on the pipe and a "C" clamp to boot!
I heated the pipe to glow red, (watch too much will start to "sweat" the metal) I popped 60 lbs of air into the the pipe and TA DA it poped out!
I got sooo stoked, I did 2 small ones to almost perfect sucess.
Just thought I tell everyone!!
Joe

2001 KDX 200 Pipe dentless!
2-2001 TTR 125 Boy"A"'s and "B"'s

Theres living, (racing) and there's existing, (between events)

atc3434` · Apr 8, 2002

Nice! I've seen that in a mag, but wasn't sure if it would really work good, now I know! Bike must have fallen hard to dent that armor gauge stock pipe! Or was it aftermarket?

Kaw_Boy_5 · Apr 8, 2002

This is definately not recommended. If you are going to try and fix a pipe yourself please do not use air. You need a gas or liquid that will not explode if you get the metal too hot. I am glad to hear you didn't get seriously hurt trying to save 40 bucks.

jmics19067 · Apr 8, 2002

definately have to be careful thats for sure. once I didnt clean the carbon out of the pipe . launched one of the plugs across the shop witha heck of a pop and had a jet engine type of flame screaming out the end. Deafening roar and scared the the crap out of me luckily noone got hurt and all involved can laugh at me when we have a few beers remembering stupid stunts we pulled. Any more I clean the area scribe line up marks in the pipe cut the pipe in half witha hacksaw hammer out the dents with an anvil and then weld it back together.. And yes the pipe gets shorter each time affecting performance . But that incident was way too close of a call for me to try popping out the dent with it sealed and heated

Kaw_Boy_5 · Apr 8, 2002

Once again, it is 40 dollars to have this done right. 40 DOLLARS.

RioRanchoKDX · Apr 8, 2002

Where to send $40

Explosion is a bad thing... right/

Where can we find a list of places to send the pipe (or pipes in my case) for dent repair??

michigan · Apr 8, 2002

Joe28,

Did you heat it first, then cap it and pressurize it? Seems like it'd be pretty safe that way.

Kaw_boy,
Chill! If he blows up, be can always sue the magazine for bajillions of dollars!
40 psi isn't that much anyway...
Doesn't schedule40 pvc and abs have a burst rating of 240psi or so? And that would surely be with a safety factor.

fatty_k · Apr 8, 2002

Joe, was the pipe dis-coloured at all after you fixed the dents? Also, if you can, use an inert gas so it dosn't blow up or catch fire.

joe28kdx · Apr 9, 2002

Maybe luck was with me

Before I poped the air into it I heated it up. The small soft plug was not a complete seal, this allowed air to excape if PSI built up to high. There was some discoloration to the pipe afterwards, heck anytime you cherry a piece of metal up it'll do that. I painted the pipe afterwards.
It was a Dyno Port pipe, the stock one, (made out of old steel water pipe I think could survive a side winder missle blast!)
It wasn't the money that prompted me to do it, it was, 1, the need to go riding, 2. to see if it works, 3. I like to do everything to my scoot.
I cut one open and banged it out before, but that was a really bad crush, not a dent, when we were done it had a lot of ripples in the metal where it streched, it worked, but looked ugly.
Common sense will tell you to point the plugs away from you, (I hope)
I've been a mechanic for 30 plus years, so maybe somethings just come more natural to me.
If you're afraid of an explosion you could fill you pipe with oven cleaner to loosen the carbon and wash the fuel out, them rinse it well with water and try it.
The C clamp was a back up to the chain and the strapping was super secure, so I think I was way safe, but as always things happen.
My advice set up time is critial and look at every angle before you fire up that torch!
joe

jmics19067 · Apr 9, 2002

My advice set up time is critial and look at every angle before you fire up that torch!

that is all I really wanted to say my mistake was that I didnt clean out the carbon. I used to straighten my pipes like that for a long time. I really do like the idea of using an inert gas. Maybe making a cap witha pop off valve from an air compressor also.
after I blew the one frost plug out I made caps out of steel and then braized them on. Did one like that was very time consuming though cleaning off the old brass when I was done. I find that just cutting the pipe in half and using the anvil and a dinging hammer for body work is the quickest easiest safest way for me . I really dont worry about the large shallow dents I get in the big middle section of the pipe I only worry about the crushed sharp dents by the head pipe. Maybe I lose a millimeter with each cut so as advanced of a rider I am < :confused: > I figure I have about 5 /10 repairs before I notice the difference.

slcyclerace · Apr 9, 2002

Boy, that was a dangerously , for lack of a better word,silly thing to do. I could fix pipes in my shop but I don't. I just don't want my tomb stone to read:"Good father, good mechanic, and good God, you did that to save $40.00!!". Take the torch that you used to save $40.00 and fire up the acyt. by itself (not much by itself except a lot of soot); next, crack the oxy. valve ... what do you get? Think of the unburnt oil and carbon as the acetylene and add air (which contains .... Oxygen) as the oxidant and what you get is a giant, uncontrollable and potentially explosive missile. I could go on about NASA and their use of oxygen with rocket fuel but I think the picture is clear. This is the reason the magazines won’t touch the subject.

Kaw_Boy_5 · Apr 9, 2002

Send it to pacific coast pipe repair. I have had great luck with them in the past. I had a platinum fmf fixed and there was zero discoloration when I got it back. Also Michigan, I am not going to chill. The problem is not with the pressure alone, it is with the heat that is being put into the metal to weaken it and then adding pressure. If that weakened spot blows out you could really get screwed up. I just hate to see anyone get hurt.

Milquetoast · Apr 9, 2002

There was a similar thread recently about a guy who filled the pipe mostly with water and plugged the ends, then heated the pipe and the steam created was enough to push the dent out. Maybe that would be a safer way to go about it?

michigan · Apr 9, 2002

I don't know about you guys, but I'm gonna quit riding my mountain bike. Those 65 psi tires are an accident waiting to happen!
Actually, I'll stop riding my dirtbike, cuz I just don't feel safe with my time-bomb of an exhaust pipe attached to my cylinder head, which has f-f-ff- fire in it!

Think about this. If you heat up an open pipe, it might smoke a little, but the friggin thing isn't gonna blow up. Now, if it doesn't blow up while exposed to air at atmospheric pressure, its not going to explode if the air is at 40psi. Its no more combustible then than it is without the pressure.
And to think that a steel exhaust pipe is going to split open and throw shrapnel because it has been heated and pressurized to 40 psi is ridiculous.
*IF* (a very, very big if) it did tear, there wouldn't be a dismembering explosion, just the brief sound of air rushing out.

I'll bet the guy at the pipe repair shop is reading this thread and laughing his ass off.

Kaw_Boy_5 · Apr 9, 2002

Michigan, good luck. Milquetoast, I have to agree that is a much safer way to do this. Water is a noncompressible fluid and will be much safer. If you are going to try this at home fill the pipe up with water and then supply the pressure with your air compressor.

michigan · Apr 9, 2002

Well then, if heat will make the pipe weak enough to fail with air, it should fail with steam too! And steam is HOT, HOT, HOT! Rember, steam starts at 212 degrees fahrenheit and goes up from there! And unlike hot air, it retains that heat!
So, if we're gonna blow up our pipes, we shouldn't do it with steam!

Kaw_Boy_5 · Apr 9, 2002

The pipe is filled with water. It is not the steam that is pushing out the pipe, it will mostly be the water pressure against the wall. Think about it like a balloon. Take a balloon and fill it up with air and another with water. Stick a pin in each and see what happens. This is because of one fluid is compressible and one is not. I understand a little steam may form in the pipe while doing this but it will be a lot safer than air. Sorry is we disagree, I am not trying to get you fired up, just giving some friendly advise. You will probably fix 50 pipes your way and hopefully never get hurt.

michigan · Apr 9, 2002

Kaw,
Thanks for being patient with me. You're not getting me fired up, but this stinking job is!!!
Anyway, to build on this topic, think about a volume of water. If you increase the temperature enough to turn that water into steam, the volume will increase exponentially because of the phase change. Won't this create a HUGE amount of pressure?
Heating a volume of air will create a need for additional volume, but not much.
This is assuming we don't an explosion from the cabon/oil mixture in the pipe.
Again, I apologize for acting like a weasel.
Let's keep bouncing ideas around. Maybe a pipe repair guy will eventually step in.

Kaw_Boy_5 · Apr 9, 2002

You are right that as you start to convert the water the steam you will build pressure. I guess the safest way would be to have a way to regulate this pressure. I am assuming that you would fill the pipe up, apply pressure (40 psi or whatever the magic number is) and then start to put the propane torch to the dent. I wonder if you could get the dent hot enough to pop out before the water inside stated to boil. I have to agree, about work getting us down. I want to go ride. I see you are from Rochester. How is the old cornstalk water tower. We try to get up there each year for the race in August and every year have a great time. Last year we ended up in a small town outside Millville at the Corn on the Cob Festival.

craig_enid · Apr 9, 2002

What about.....

Instead of heat, what about filling pipe with water, plugging it, then sticking it in a freezer?
I'm not sure of the physics of expanding, freezing water.... if it would work on the dented area before doing any damage to any undented area....
Or how many freeze cycles you would have to run it through to pop the dent out.... 1 or many..... :think:
Input?

michigan · Apr 9, 2002

all of the water will expand evenly throughout the pipe. There would be no way to isolate the expansion to just the area of the dent.
I've heard that this splits the pipe at its seams, but I don't know the frequency. This is just what I've heard.

Kaw_Boy_5 · Apr 9, 2002

Tried this one time and the dent was pressed out but I didn't catch it soon enough before the freezing pulled the pipe apart at the weld. Maybe if you watched it constantly you could pull it out before this happens but I am not sure.

craig_enid · Apr 9, 2002

Now if we were WAY up on our physics, we could figure out how much of a bubble to leave in it, so the freeze expansion would be complete when the pipe was dentless, and before damage! :confused:

Robcolo · Apr 9, 2002

Joe28KDX you "done Good" I've used this method [air & torch] for 25 years with never a problem. Just make sure you burn out the pipe first & wear safety glasses. Worst thing that can happen is a small localized burst if you overheat a spot. Use a "soft" flame to avoid that. Ignore these other girls and their speculations

jmics19067 · Apr 10, 2002

what happened to me was not a speculation!!!!!! but I doubt you will ever believe me. so have fun and good luck.

Pipe Fix

joe28kdx

atc3434`

Kaw_Boy_5

jmics19067

Kaw_Boy_5

RioRanchoKDX

michigan

fatty_k

joe28kdx

jmics19067

slcyclerace

Kaw_Boy_5

Milquetoast

Uhhh...

michigan

Kaw_Boy_5

michigan

Kaw_Boy_5

michigan

Kaw_Boy_5

craig_enid

michigan

Kaw_Boy_5

craig_enid

Robcolo

jmics19067

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