Petrol Tank woes

[jhg1958]

Towards the end of last summer I started to notice a smell petrol around the bike that only got worse.  Now I am getting petrol drips from the back LHS of the tank.  I was unable to see the source although there was a bit of bubbling of the paint.  So I bought a cheap endoscope from fleabay I must admit it works a treat.

Unfortunately I still cannot see any leak however I can see a lot of corrosion that looks very uneven probably due to condensation.

I have read on this forum about cleaning the inside of the tank with nuts and bolts or even gravel. I am worried about making any pinholes worse.  Any advice would be welcome.

As an alternative I am tempted to use “Evaporust” to remove the rust before POR15 tank sealer. I took this from motorcycle forum https://www.motorcycleforum.com/threads/por-15-gas-tank-restoration-kit-how-to-tips.199570/

First job is to get some plugs for the tap holes I think they are 3/8” BSP thread. Then buy the rust remover.

I was wondering how to seal the filler cap the only way I can see is to put some plastic under the filler cap.

See the pictures of the inside of the tank.

I was lucky.  When I removed the tank found that it was rubbing on the oil feed to the rocker box!  I am not sure how much damage might have been caused before I noticed the oil. See photo.

John

[trevinoz]

To seal the cap hole make a bung out of thick rubber.

[limeyrob]

Try golf tees, they are very handy for all sorts of things.

[CheeserBeezer]

My method for checking tanks is a s follows. Flush the tank out with soapy water, then sit it on a radiator until dry. Fit both taps and attach a fairly long piece of tubing to one of the taps which should be left open. Close the other tap. Fit the petrol cap down tightly using an oil filter wrench, then just block the breather hole in the cap with some tape. Paint the suspect area of the tank with soapy water. Blow into the tank down the long pipe on the open tap. That's all the pressure you need and you'll see bubbles in the soapy water where the holes are.