:banana:

Pictures aren't so great and for some reason I failed to take one before I started the process. But the dent was about 3" long, 1.5" wide and about 1/2" to 5/8" deep. Pretty substantial dent right in the "dip" of the head pipe.

This came off my 450KTM. I figured up the volume in order to only fill the area where the dent was. Poured in 11oz of water. Froze for 2hrs--took out--thawed out (took first pictures) at this point the dent had pushed out about 1/4 of the way.



Water back in..let set overnight (6hrs)...pulled out and voila!!! fixed..still scratched but fixed!!! :banana::banana:..sure wasn't wanting to buy a new pipe!




I know the location of the dent in this pipe really lent itself to doing this procedure..had the dent been in a straight section it would have been much harder to do without damaging the rest of the pipe.

I did this a couple of times.. there are some negative things in doing this
I noticed that it DOES get the dent out.. but it will make your pipe less strong than it was in the past, because the dent isnt fully "out" it has small grouves in it still and these grooves are where the weaknesses are..
If you fall over on the side or hit something.. The pipe WILL bend at this location as it was already weakened in the past.. so to make things short,your pipe is not as tough or intact as it was in the original shape.. its still weak. And it will be especially weaker while running hot.

I had 4 friends take dents out of headers and 2 headers in my experience.. and ALL of them failed at the exact location where the original dent was.. it ended up looking "squashed"

Ya, I fully expect the next hit in that area will dent it back in!

zwr250f said:

:lol: funny how that works :smirk:

^^^:lol:...ya that was kind of a dumb statement after I re-read that...:lol:

But we understood what you meant:banana::banana::banana:

Water's greatest volume is just before it freezes, at about 2-3 degrees celsius. Thats why the dent doesn't come out until you just start to thaw it. The ice on the ends of the ice-mass plug it in place.

Really cool (pun intended)! Glad you shared!

Froze mine out too last season.. pipe has been fine ever since, this is with hard off-road riding and racing.

How many times did you freeze it? Just once? I had to do mine a couple times.. Did you cap off the ends? I had to cap the ends off on my pipe, i was freezing it in a deep freezer and the the water just flowed out the end as it froze and didnt pop the dent out. I then realized that drain plugs for a laundry tub are a great fit, so I plugged each end with them, and then it popped it out. i kept an eye on it though I was afraid of cracking it.

Froze it twice.

Plastic bags with duct tape over the end, although my water never even reached the ends

It was a bit perplexing to my mind why the water wouldn't keep expanded towards the area of least resistance (the open ends of the pipe) but instead forced the dent out.

Quote

Just wondering on what planet this happens on...... :lol::lol::lol::lol::lol:


ACTUALLY, Water has it's SMALLEST volume at exactly 4 degrees Celcius, it expands from there if either heated or cooled.
Water freezes (becomes a solid) at 0 degrees Celcius but keeps expanding as it gets colder and colder, so when ice increases in temperature, it is shrinking in volume until it reaches 4 degrees C (just above 0 it becomes water but still shrinks in volume until it reached 4 deg. C), once it gets above 4 it increases in volume once again, so it is NOT the melting of ice/water that gets the dent out.

Ice at -10 celcius is bigger in volume than ice at -2 celcius....

look at an ice cube tray - it's a great example - fill it to the top with water - the water is level with the top, let it freeze to -2 and it will have a slight bump upwards because it's volume increased, continue freezing it to -20 and the bump gets bigger as it gets colder.

The reason the dent gets pushed out is due to the expansion taking the path of least resistance, there is more friction for the ice to expand and move all the other ice molecules down the length of the tube than there is for it to push out against the tube wall

Remember that the ice is trying to expand equally in all directions and the ice further down the tube is actually also pushing back on the ice near the dent so the ice near the dent decides the pipe wall is less of an obstacle than the ice beside itself. Kinda hard to describe but that's the way it is because the ice is a solid.


Edit - oh, and I should mention that at just before 100 degrees C - water is at it's largest volume, at 100, it changes state into a vapour....gas.

zwr250f said:

Good post.. :thumbsup:

matt4x4 said:

Ooops, your right. Maximun density at +4 celsius.
Jeeesh, and I have a PhD in Chemistry! :banghead::bonk:
Your right, the force that gets the dent out is below freezing.



Sometime I just need to be slapped......

This is really neat. come this winter(freezer is too small) I think I may want to try this trick with my aluminum fuel tank. It has a knee dent on each side and one across the top.
anybody see a reason this shouldn't work? Or turn out bad?
Of course I will remove the petcock so as not to freeze it and will be solvent flushing the water out before using it again.

the real question is can u tell a diffrence in performance now that the dent is out of the pipe ? , my 300 has a few nice sized dents that i may have to try freezing out

DrThumper said:

It's "you're" not "your"

PhD? Really? :thumbsup:

ghkj21 said:

It will work.

Some comments on pipes; it helps if you can get the water in the ends of the pipe to freeze first so they dam the water as it cools towards freeze near the dent.

Thanks for sharing, that's very cool.

What's with the crack from your spring attachment to the end of the pipe?

DELTA 41 said:

Not a crack, the exhaust comes out as dual headers then immediately into 1.

zwr250f said:

I'm not sure how hot those pipes get but is it possible that the heat may re-temper it after being cold formed? Or maybe putting some heat on it and then running it to slow the cooling process (thus treating the metal)

biggziff said:

Blow me.
I'm going to proof read everything you write from now on.

At least I stood up for my mistake.