What is the safest way to get dents out of my exhaust pipe?

[ACMX]

I went racing this weekend and ended it off with a pretty bad crash

I'm fine but I dented up my FMF Gold Star Series exhaust pipe

What is the safest way to get dents out?

I am afraid to freeze water in it, because I don't know if it will crack open.

[riffraff]

torch and compressed air

[ACMX]

I'm feeling a bit left out on the details 

[JohnN]

Check these folks out... they also have some tips to repair them yourself.

http://www.piperepair.com/

[SachsGS]

Remember that a 100 psi air compressor, a torch and two stroke goo equals an internal combustion engine.Be careful.

[DangisMX]

There are several ways. You could get someone else to do it for you. I've heard lots of good things about Pacific Crest Pipe Repair company that John pointed out. If, on the other hand, you are a bit of a DIY fan like myself, you could try fixing it on your own .

The first method is to fashion some sort of plugs for the ends of the pipe. They have to seal properly and stay in there pretty tight. Then partially fill the pipe with water and place it in the freezer. As the water turns to ice it expands and pushes the dents out. The downside of this method is that it can actually tear your pipe in half if you fill it up to much or leave it in the fridge for too long. I've heard some people plugging up only one end so that the excess ice can go out the other end, but i would imagine it might relieve the pressure to much and then nothing will happen.

The other, far more popular method is the old compressor and blowtorch approach. You seal the pipe, heat the dent until it's glowing hot, and then apply pressure (or vice versa). I tried it myself with a propane torch, and i don't think it was hot enough, even though I raised the pressure until one of the seals failed and shot some 20 meters down the street (good thing no one was walking by ). Then again, i tried it on a thick stainless steal four stroke vintage russian motorcycle header pipe . It might be hot enough for the thinner modern two stroke pipe. Also you can even use a manual car tire pump if you have one, instead of a compressor, just put a tire valve in one of the plugs... Just be carefull not to actually melt the pipe if you use something like oxy acetylene torch.

And finally, you can drill a hole, put a hook through it, and pull (or hammer) on the hook until the pipe is straight (or weld the hook straight to the pipe and cut it off later). You will have to weld the hole shut again and it will look a tad rough, but it works .

[Coop]

Check these folks out... they also have some tips to repair them yourself.

http://www.piperepair.com/

+1, this is what I would suggest since you want the safest way.

[Super Trucker]

That link John posted , there the real deal. In 97 I raced  Millville,s am. day, I asked John Marten the track owner if I could ride monday if I did some work he said sure. Sunday night I went to the post race party, had a blast then monday morning I get to the track hanging around John,s house, his pal a vet a rider Mike Daughty the twin brother of the owner  vintage iron,used John,s cr250. We had a blast we burned up more than 2 tanks of fuel. The track was alot faster and smoother than am. day,then Mike had to split back to Cali and I had to work now with a diff. Mike he,s from Tx. We went through the pits and I grabed garbage cans and put them on a hay wagon, I was eating m&m,s and pretending to drink stuff I found, Mike was laughing. I grabbed a  custom PC pipe for a KX125, THE PIPE was flattened, I shipped it to pacific, just to see if they could repair it. They did a awesome job, I then sold it to a friend,just broke even.

[Dirt Addict]

yup, pacific crest pipe. 

[MyckMcClung]

be sure to wear a helmet and safety goggles when attempting any of these methods.