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Tank tunnel widening technique

7082 Views 23 Replies 11 Participants Last post by  mattsway
Hi. I have a CB200 tank to go on my XBR500 build and need to get clearance where my frame rails attach to my top tube. At this location, the tank tunnel is 130mm and if possible needs to become 160mm. Having googled around, I hope to be able to use a plastic mallet. Any advice on weight/shape of mallet and technique - do I strike against the inside face of the tunnel first, or the bottom edge where the wall and bottom of the tank meet? Any prep to help move the metal most effectively? I thought about filling with boiling water, but I could always purge the tank of petrol/gas fumes and use a butane torch. Many thanks.


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Good luck with that - I tried to dent the tunnel on a GS650 tank to fit over the head of a 450 and only had to move part of the tunnel less than 1/2 inch each side in just a small area and the outer skin still deformed.

You'd probably be best off cutting it out and re-welding.

But I doubt you are set up to do this seeing you are asking here.
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