Fantic lower frame tubes bending

[TRS Fan]

Not wanting to revisit the much talked about issue of Fantic frames with cracks / movement at the steering head, as that as been covered many times previously.

The lower frame tubes under the engine are also prone to bending and in some cases flattening slightly against the underside of the engine cases - see attached images.

The two images are of two different bike circa 1984. Both have been hit from underneath, and then hammered from above to allow access to remove the casing. I believe most Fantics were fitted with a plastic sump guard originally.

Looking at images of refurbished bikes, none of them have this issue, and the engine cases are well clear of the frame tubes, as they should be. Is it a case of looking for a bike with tubes that have not been abused (probably hard to find?) or can they be repaired successfully.

I am aware of Fantic making frames with tubes within tubes for strength - does that apply only to the headstock area or the lower tubes under the engine?

If the lower tubes are 'tube within a tube' it makes cutting and re-welding more tricky - and this is an area likely to be subject to impact loads at some point.

Any thoughts or existing solutions would be welcome.

Edited January 8, 2023 by TRS Fan
additional information

[feetupfun]

When a frame becomes pushed out of shape by riding, like in those photos, I take the motor out to make it easy to push it back into shape.