So I’ve recently noticed a few pinhole leaks along around the weld seam. I’m eventually going to get the tank repainted so I’ll most likely have them weld up the pinholes at the same time. In the mean time, does anyone have any recommended temporary fixes? I’ve seen a few fixes (por-15, permatex, jb weld) on early posts from a few years ago but wanted to see if anyone knows of any good up to date solutions.

Best thing is to weld them but before strip the paint right off as that will often show up some more and sometimes you just have to chuck them in the bin.

I had my tank repaired with Pattex 2-components epoxy repair paste . Very easy to use, very effective, yet it was not obvious as the leak was at the basis of the mounting plug, at the bottom of its will, under the tank. The bike had fallen and the plug was forced inside, creating a crack.
It was supposed to be an emergency repair, made at 3000m. high on a moutain track in the Alps to stop pouring fuel, but one year after, not a single drop of fuel has leaked from there.
The age of these tanks may create problems when welding them...the alloy loses its consistency, turning into flakes.

futech wrote:So I’ve recently noticed a few pinhole leaks along around the weld seam. I’m eventually going to get the tank repainted so I’ll most likely have them weld up the pinholes at the same time. In the mean time, does anyone have any recommended temporary fixes? I’ve seen a few fixes (por-15, permatex, jb weld) on early posts from a few years ago...

Back in the 1980s when I rode my trusty R100CS all around the country, BMW and Harley bikes came OEM with the insides of their steel gas tanks painted to prevent rust from the inevitable H2O condensation inside the tank.

Understanding that the K bike tanks are aluminum, and thus rust-free, I wonder with my 24-year old K75 about the (in)advisability of painting the inside of its much, much more complex tank interior. Why do it: because a layer of appropriate gasoline-proof coating could prevent age-related tank pinholing described here. What could be problematic: the complexity of trying to get a coating to seal and adhere to all the inside shapes and pieces of a K bike's aluminum tank, without messing up the submerged fuel pump & pressurized gasoline supply system.

At the least, perhaps coating the inside bottom 1/4th of the tank would yield nearly all the benefits with fewer problems.

Since our aluminum tanks are long out of manufacture and are now a classic finite resource, I'm curious if anyone here has tried, or heard of such an attempt at inside-coating these tanks. Comments?

The reason the tanks corrode is due to running ethanol laced fuels. A bacteria forms in the ethanol water mix in the lower recesses of your fuel tank. The bacteria then secretes acid which proceeds to eat away at your tank. It will also degrade your fuel pump damper and hoses. A mate had problems with all four of his bricks tanks and pump dampers. One tank had been sealed with a coating which was yellow brown in colour, brand unknown. The coating started to flake off in small pieces and chunks. 

There are apparently good coatings out there but you need to do research. I have never ever run ethanol and have not experienced any problems. When I first got my brick about 20 years ago I was told to replace the pump damper. I replaced it even though it was fine, it has now resided as an unused spare for the last 20 years.
Regards Martin.

In my area, I'm happy to see that more and more sources of "pure gasoline" are available.  However, in years past (7 +/-?) I coated my Laverda fuel tank with the product Caswell sells.  It's been subjected to a fair amount of ethanol fuel over the intervening years but the coating remains intact.  Good product to consider if you decide to coat a fuel tank.

jbt wrote:The age of these tanks may create problems when welding them...the alloy loses its consistency, turning into flakes.

When this happens a higher frequency of the TIG is needed, wont always solve the problem but usually does.

brickrider2 wrote:...in years past (7 +/-?) I coated my Laverda fuel tank with the product Caswell sells.  It's been subjected to a fair amount of ethanol fuel over the intervening years but the coating remains intact.  Good product to consider if you decide to coat a fuel tank.

Uuuuu! Nice. Thanks.

DadofHedgehog wrote:

brickrider2 wrote:...in years past (7 +/-?) I coated my Laverda fuel tank with the product Caswell sells.  It's been subjected to a fair amount of ethanol fuel over the intervening years but the coating remains intact.  Good product to consider if you decide to coat a fuel tank.

Uuuuu! Nice. Thanks.

...and now having read up on the Caswell Gas Tank Sealer and watched a YouTube or two on the application, I guess I know what my Winter motorcycle project will be haha. Thanks BrickRider2!

Had mine welded  and pressure tested  

Under test they found a couple of more pin holes 

Ended up having  8 holes welded up no leaks now 

Thankfully I was able to find a radiator place who was able to weld up everything. I was a little worried that the pitted area was a no-go. For now I’m holding off on a sealer, but I did end up doing the metal prep step to clean it up a bit.