Scooterotica

Are stainless steel fuel tanks ok to use on a tuned lambretta, as if I remember correctly a few years ok, people were saying there scooters were failing due to reaction of the steel and petrol? thanks

I couldn't say anything with regards to the steel/petrol, but stainless is often polished using abrasives sometimes leading to abrasive materials going into the engine with the fuel. Also stainless is more susceptible to cracking with vibration

I don't recall any concrete proof and I think the jury is still out, but, running mild steel tanks doesn't seem to raise the issues (real or not) of stainless tanks.

Like with any tank - they need cleaning out properly before you start.
I fitted one to a pals TS1 many years ago and it's done plenty miles on any petrol as it's a rally bike - done plenty long slogs
It was a SSC mid range.
I've stripped it twice for servicing (rings/reeeds etc), the last time just before lockdown and the top end was perfect.

Mild steel can be as bad. I put a mid range one in my lince and only gave it a cursory rinse thinking it'd be OK.

1200km done I lost compression and hard starting and on dissembly the ring gap was 5mm and the rings wer half the thickness they should have been and the bore was worn out.

After looking at other causes I drained the fuel through a coffee filter and found a fine metallic grit in the paper - this was not present in the carb filter which likely means it was going straight into the engine.

New piston and replate required.

I can't imagine there's a problem between the stainless steel and the fuel - stainless steel tanks have been used on boats for decades.

But polished ones that haven't been cleaned properly of polishing powder? I can see that being a problem.