Lawnmower Engine Starting Tips??

[sanddrag]

Today I picked up an old lawnmower (looks like the push type but has an engine) with a 3HP Briggs and Stratton Horizontal engine for free (score!) And it runs too, well, sort of. I had it running pretty good, I got it to rev really well (really high and smooth, punchy on the throttle too) but it would die when I let it idle for more than a few seconds. I knew it wasn't the idle stop because it was already idling pretty high. So I tried adjusting the mixture needle and then it wouldn't start so I tried putting it back and it still wouldn't start and now it is probably way out of adjustment.

I must have tried pulling the starter 100 times with different combinations of needle setting and choke and the only thing that could get it started was a little gas right into the carb.

Most of the times I had the engine running, it seemed like it wanted probably like 3/4 choke to keep it running well.

Anyway, now I really can't get it started at all and I'm not sure what choke and needle I need. I filled it with oil because it was pretty low.

The gas and spark plug are probably old, but as stated it was running okay (until I fiddled with it of course). I will try changing the spark plug (if it isn't seized in there) but I don't really have anywhere to put the old gas so I guess I can just put some new gas in to mix with it.

Anyway, does anyone have any tips to get this thing started easily and running like a champ? I'm afraid all pull out my arm if I pull that starter any more. I looked but I couldn't find any manual or starting procedures or needle setting or anything online.

Eventually, I want to do something cool with it like make a generator or a gokart (the mower already goes really fast as it is) or something of the sort.