I'd been smelling gas occasionally around my CBR and figured it was probably old fuel line or something like that. Turns out the tank is leaking under the front mount.

A quick search here turned up some posts that show it has been a common problem. One solution I saw was JB Weld around the perimeter of the mount. Doesn't look like a long term solution to me, or even short term since it won't stop the flexing that likely led to the problem in the first place. Plus, it doesn't stop the leak at the source, which would seem to be the ideal. So about the only other option is a liner. I hate to do it. The interior of the tank is perfect. I first used POR15 on my '75 CB750F tank after a 19 year old Kreem coating gave up the ghost from whatever evil concoction is in contempory fuel. I did that in 2008 and it is still holding up, so I'm leaning toward that. What concerns me is how smooth the interior of the tank is. I wonder it the Metal Prep etching will be sufficient to prepare the surface for a lasting bond. The old 750 tank was much rougher inside from rust. As anyone who has had to deal with one can attest, failing tank liners are a real pain in the patoot.

Any recent longer term experience out there that will indicate how long some of the various repairs have held up? Thanks.

 

Flippin heck, couldnt be in a worse place.
Ok, so you could fill it with water and flip the tank as you have it and try soldering it, using a small brass metal fillet, providing you have enough metal under the bracket, failing that, it may be another tank, if available.
Mike.

 

I have used jb weld on a pick up truck gas tank, where the metal holding trap rubbed thru.

The jb weld, held for over 2 years.

I think I'd try that, before trying to weld, or brase.

That could get u buy until u find a better long term solution

 

For an update, I went with the POR15 liner. So far so good. For anyone else that does this, don't forget to keep the tank vent clear. I neglected this and plugged it up a little. I was able to clear it by running a piece of 3/32" cable up through the nipple on the bottom of the tank and using it like a drain snake. I was lucky as the POR15 is pretty hard when it cures.

 

I would think it would be preferable to weld it to stop the flexing. There are some really good welders out there that would have no issue welding on it. Preferably a guy that does mostly welding and paint on motorcycles.
If I where to just seal it around that area I would use this sealer here we use to seal aircraft fuel tanks and fuel panels.
It's extremely durable stuff and some (not much) flexibility. I used some of it years ago to overlay 2 spots inside a new motorcycle fuel tank that the manufactures inside coating didn't get to and it is still doing great

https://www.amazon.com/PR-1422-Aircraft-Fuel-Sealant-SemKit/dp/B00DJAVVFQ

 

Update - the POR15 fix is still holding up.