yep, way too little.. what are the symptoms? engine slow down adn stall above .5kw? eng speed constant but voltage droops? what kind of generator? Induction motor? wound field? synchronous motor? you need to give more info...
if el cheapo deluxce, it may have bad capacitor after a few years of sitting and absorbing moisture..... far out semi-useless GUESS w/o more details... I had a 4kw output about 100watts and voltage would just drop - engine was fine, no droop, when my little cap went bad. new cap and back to 4kw output.....sometimes bridge rectifier on field goes and does same thing, had that on a motor home once....
but no telling if this is YOUR case w/o more info....