A forum for owners of Yamaha TTR250 trail and enduro bikes!

Hi Rob

That is a very common problem on the metal tanks. 

Over the years I have successfully repaired a few tanks rusted through at that point. I did do a pictorial guide on the forum but darned if I can find it now!

Basically the stages are:

1. Wire brush the heck out of the tank at that point so you have absolutely clean rust-free metal. You need to be quite aggressive to get the flaky stuff off.

2. Using the rounded end of a  ball pein hammer (or similar tool) tap down the damaged area so that it is at least few mm below the good surface surrounding it.

3. Degrease the area thoroughly - must be no trace of fuel or fuel residue on the bare metal.

4. Fill the area using Isopon Leak Stop, or a similar fuel-proof filler, and sand it back level to the good surface. You may need to apply a couple of coats depending on how big the rust holes are. Don't fret if some of the filler goes inside the rust hole as this will help the filler adhere.

5. Paint the area

6. Maybe put a small strip of sacrificial tape over the repair to help protect the new paint?

Hope that helps.

Brian