Unrestored tanks is for MUSEUM stationary bikes ONLY! Unrestored original tanks should be avoided in my opinion! And a restored original tank needs a new coat of paint anyway so the advantage with -original metal- is only in the head of the owner/restorer.
It is way safer to have new made tanks as the solder in old tanks crystallise with age and gets brittle or is pried apart by migrating rust. Rust never sleeps, it can lie dormant, but is always ready to make new territory. With new tanks the metal is fresh, strong and not corroded.
The strain on the tank, full of gas and oil out on a bumpy road is often overlooked, only the fluid weighs about 12 kg and is sloshed around and jolted in potholes on the road.
If a unrestored tank doesn't crack at the seam, they start to leak at the nipples and screw lugs, and if they don't leak there, they leak between the oil and gas tank or simply right through pin point rust holes through to the outside. If all that is not happening you can be sure the baffles or reinforcement plates inside is rattling loose.
The obvious risk of a catastrophic fire with a suddern large gas leak is not intelligent to take. Or the risk of gas diluted oil that can result in a ruined engine.
Put the original tanks on a shelf! Paint can be distressed so it looks like patinated, if somebody would fancy that.
