Expansion chamber repairs

[rogerh]

I have a pipe off a 200EXC that needs some pretty serious bending and twisting. Not too worried about dents, but the front bend is pretty badly out of shape, and does not sit properly in the flange. I have heard of a couple of methods. The freezer one, and the heat and compressed air method. Any suggestion as to which would be easier? Or any other suggestions?

I am just being chicken.... Or if anyone can suggest someone in the Hamilton area that may be able to help me not screw the process up.... Thanks

[K6K]

I have a pipe off a 200EXC that needs some pretty serious bending and twisting. Not too worried about dents, but the front bend is pretty badly out of shape, and does not sit properly in the flange. I have heard of a couple of methods. The freezer one, and the heat and compressed air method. Any suggestion as to which would be easier? Or any other suggestions?

I am just being chicken.... Or if anyone can suggest someone in the Hamilton area that may be able to help me not screw the process up.... Thanks

Neither method will bring the pipe exactly into line but they might help slightly. They get dents out but dont fix twisted pipes. Force is required...mount it to the bike and see where it needs to go, left, right, up or down. Remove and put the lower mounting point into a bench vise to hold it and use a wooden handle from a broom or similar to get leverage to tweak it back into shape. It is easier with two people but either way you need to tweak it a bit, remount and see where you are then do it again. Can be frustrating but does work.

[barty5]

Neither method will bring the pipe exactly into line but they might help slightly. They get dents out but dont fix twisted pipes. Force is required...mount it to the bike and see where it needs to go, left, right, up or down. Remove and put the lower mounting point into a bench vise to hold it and use a wooden handle from a broom or similar to get leverage to tweak it back into shape. It is easier with two people but either way you need to tweak it a bit, remount and see where you are then do it again. Can be frustrating but does work.

A bit of heat will help when doing this but as said it is about the only way. if you are going to try a remove the dent by freezing id do it before you straighten out as you might find it tweaks it back out of shape. I also don't recommend going over broad try to remove dent as when we last did it the force cause by the ice expanding split the pipe open.

[camchain]

Problem with that lower section is the front part is double-skinned for strength, so it's hard to get enough heat to transfer through to inner skin (especially if creased/separated). You'll see spot welds where double skin is - only on forward facing half of pipe.

My pipe has been badly mashed/creased against frame a couple of times. Cut pipe into 2 or 3 sections so I could properly get at the squashed bits then re-welded back up. I rang up Custom Chambers, East Tamaki AKLD and that's how they do it. (If memory serves they would have charged about $200-ish? Not at all unreasonable)

After ding removal I had to break tack-welds and re-align 2-3 times before getting close enough for welding, 1mm wrong way on joint = 5mm wrong way at flange/rubber mounts. End Result not so pretty with weld lines, but fully functional and much cheaper than a new pipe (Tell your mates it's a special 'works spec' mod).

Flange will likely still be a bit out of line when finished, so slip end of pipe over a piece of wood, heat 'n tweak by leaning on other end of pipe, maybe you can get away with just this even without heat? You do need to sort it though, because pipe will vibrate and flog out the soft alloy engine port-part and you'll get a bad seal.

I did the whole thing by myself the first time (a real pita) - you really need a second pair of hands.

Not saying this is the only way to go, but just the way I did it. I have some pics somewhere - I'll see if I can find them later (Think pics maybe already in an older thread, try a search?).

[YellowDog]

I've seen pipes shatter after being frozen.

How about looking for a replacement pipe?

You never know.

[flyingcr250]

i always did mine in the vice at work, id stay away from heating it as you can run into more problems than what you started with. its just trial and error getting it to miss the frame and getting the header to sit in the flange straight.

[dave hamilton]

you could try the guys at farm and trail in te awamutu or off road imports in horotu these are the 2 places i no of that may be able to help

[rogerh]

Plenty of ideas there....

Would post a pic if I could work out how to turn img code on.

Was going to use heat, but sounds like I should be careful. Might try a bit with a slide hammer, and a lug welded on.
I am not too worried about how it looks, but it has been crook for a while by the looks of the spooge, but it has not totally stuffed the flange yet, and I would like to improve it a bit before it does. But getting someone at a shop to do it looks good too.

Edit: OK figured it out. You use a link not a img tag....

Pic here (http://www.tekowhai.co.nz/for_web/o_4f8bc5_3264_2448.jpg)

Thinking I will have a hack tomorrow without heat (and messy smoke) ans see what moves...

Will let you know