what is the best way to correct bent cylinder fins

[ghostrider]

)  Trying to correct a few fins on the barrel of my yz250g , previous owner used a jack hammer to remove the barrel and has bent the lower and upper fins (looks crap).I have thoughts of heating with a gentle gas flame and slowly levering the fins back to somthing close to the way they should be.Has anyone tried this with any success???

[Slakewell]

Old school boilermaker trick is to ( when using oxy ) is to blacken the area with most acetylene flame when the black burns off the alloy is about as ductile as it going to get 

[odd1]

Use a black marker pen and colour in where you want to heat when using the flame on the fin the marker pen should disappear when hot enough  try on a bit of scrap aluminium so you know what to expect