Hi All,
My 1990 has a tank leak up where the front mounting bracket is welded to the tank body. I know many people have had this issue and some have had it welded or brazed. Can anyone shed bit more light on how they went about fixing it? Did they fix it from within the tank or on the outside of the tank? I want to avoid putting in a tank sealer. While I know that these can often work, I'd prefer to get a more permanent solution in place.
Thanks!

 

Can be repaired from outside. You’re basically laying down weld bead or fillet of brass over crack. Also blend radius to relieve stress-riser and prevent future failure.



DO NOT use any kind of tank sealer! It will flake off in couple years and completely clogg fuel-system.

 

@dannoxyz thanks for your reply! I want to make sure that I am understanding you correctly. Are you you saying that you would essentially re-weld the spot weld? I assume you are not saying to lay a bead around the entire edge of the bracket along the tank.

 

You’re adding metal to wherever leak is. The hole that’s letting petrol out.

Typically these leaks are caused by stress-risers. Generally where parts meet at right-angles. Stress risers are created from transitions of flexing parts to non-flexing part. The bracket is thick and doesn’t flex. But loads it carries makes it move and it will flex thinner metal of tank just beyond weld. That’s where crack and leak will occur.

So to fix leak, we fill crack and hole with additional metal. And add more and gently taper it away from joint to reduce flex/no-flex transition to reduce stress-riser.


This joint will crack at right-angle joints where tubing connects to each other.



This joint will withstand exact same loads much, much better without cracking because stress-riser through joint will be lower. Forces will be transmitted through across much larger surface contact area without sudden flex/no-flex transition.



Post photo of your tank bracket where it’s leaking and let’s see how to fix this.

 

Here's a picture of the bottom of mine. I haven't figure out exactly where its leaking. As I had posted a few month back, I had just bought the bike after it had not run for a few years. After getting it all up and running (including draining old fuel from the tank and rinsing with a little new fuel) I filled the tank and then smelled gas fumes a few hours later and noticed it was wet.

 

Easy way to find leak is to clean it thoroughly. So clean you can eat off it. Then put a little petrol in and rotate tank slowly all around see where fresh petrol comes out.

Can use some flourescent dye to make leak more visible. Light up with UV flashlight or fluorescent bulb. Not incandescent party light.