I got a spare tank cheap for my CBR400rr diesel racer because it had a massive dent in the back from some poor guy's nuts after a brutal highside.

Adam (now Amanda) retired from racing and I got the tank for $25...

anyway, I weighed it and then cut the bottom out and it weighed 60% less as most of the weight was in the base. I removed the filler cap and cut out the spout etc and welded/smoothed it off and knocked out the nut dent. Another 10%

Salvaged a gas tank from a lawn tractor which was a light resin item.

Saved 55% total weight and cost a total of $40.

A good gain for bugger all cash I thought.
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Stop sniffing my ring

MC28SP
KLX110 hotrod
CAG Minimoto
1997 WRX
21 Speed Bike
162 Smurfs