Petrol tank removal

[Phil C]

Yes I know, I have to ask just about every step of the way. I need to remove the tank in order to examine the wiring on my 1965 B40F.  I have taken the two nyloc nuts and the metal strap off, and the tank appears to be loose both at the back and at the front, but something seems to be holding it in the middle. Peering up underneath I see foam, wires, and a plastic tie, but don't know if that tie is holding it, and can't think how it could be.  Don't want to tug too hard on the tank if something is holding it. Could it be?  Phil (novice.)

[Mark B]

You have taken the fuel pipe off the petrol tap haven't you?! (Yes, I had to learn somehow too...)

[Phil C]

Yes, even I didn't miss that!

[A10 JWO]

Probably rubber-foam holding it down. Sit on the bike and pull slowly away from the yokes, it will come off.

[JulianS]

Centre nut under the rubber bung in middle of tank.

See illustration below whuch show the centre assembly unber the rubber bung.

[Phil C]

I don't think mine is like that - I undid two nuts holding a strap under the tank near the front.

[JulianS]

You should have a rubber bung in the top of the tank, pull it out and have a look.

[AWJDThumper]

As said, providing you've got the correct tank on the bike, it just sits down on to three rubber buffers fitted to the frame. The tank centre bolts then stops it pulling off.

[Phil C]

Okay thanks - I guess being as I took off two nyloc nots holding a metal strap, my tank must not be standard for a B40?

[JulianS]

The metal strap is a standard feature, prevents damage to tank by flexing. It does not hold the tank in place.

If there is not a hole with a rubber bung in the tank, suggest you post a photo.

[Phil C]

Got the tank off eventually.  You were all right, of course,  it was a single bolt and the two nuts I undid weren't holding it to the frame atall. I still had trouble getting it off but eventually it came free. The main problem was that I am an idiot! - why didn't I look under the rubber grommet until advised to - twice - by Julian?! I am really enjoying all this but it's not doing a lot for my self-esteem! The frame where the tank was sitting is still covered with foam rubber, wires, etc at the moment.

[AWJDThumper]

Not sure why there is foam on the top tube. The tank should sit on 3 rubber buffers; one at the back fixed above the top tube and 2 at the front fixed to a cross bracket. The tank tunnel should not come into contact with the top tube. I can't really see from the pic whether you have the front cross bracket and it looks as though you don't have the rear rubber buffer fitted.

[Phil C]

I've got a rubber button from the back. It's a bit worse for wear - seemed to have string wound round the smaller diameter - don't know why.  Might get a new one I think. Also a flat piece of rubber a few mm thick and about an inch or so square - not sure where it fell from when I removed the tank. And of course the metal strap which has two rubber buttons - but as discussed that's not holding the tank in place.  Not sure about the cross bracket, I'll have a look tomorrow. Fingers crossed. I guess I'll take all the foam off for now anyway so I can get a proper look at everything.   Phil (novice.)

[AWJDThumper]

The picture shows the frame for a C15. The three rubber buffers push into the holes in the rear bracket on the top tube and into the cross bracket under the front of the top tube. When sitting on these buffers, the tank is very stable and its tunnel does not come into contact with the top tube.

The arrangement for the B40 is similar but instead of a front cross bracket being welded to the frame, the bracket is bolted to the frame via two horizontal brackets welded to the frame as shown. It sounds as though your's might be missing the cross bracket and the tank is resting on the top tube at the front?

[Phil C]

Here are my tank fastenings etc with the foam rubber removed. Looks fairly standard, I hope? Don't know why all the foam rubber.

The centre bolt set-up doesn't look quite what I expected. You'll see on the photo there is a rubber bit which the centre bolt pokes through. A penny washer sits on top of the rubber bit, then a spring washer, then the nut. Is that how it should be? Doesn't look quite like the drawing, does it? The nut was only tightened against the rubber, so just felt spongy rather than nipped up against anything more solid.  Is that really how it should be?

The squarish bit of sheet rubber fell off from somewhere when I removed the tank. Any idea where?

Phil (novice.)