I know mine is far from stock but I had it on scales twice. The first time it was on a big lorry scale which had a error of +/-20 kg. With 3/4 of the tank it weighed 1440 kg, without the driver.
A couple of years later I got it on corner balancing scales and, with about 1/2 a tank, it weighed 1445 kg, without the driver.
Can you get yours on a scale to see what it weights?