Kz305 wobbly steering

Hey there, just bought an 82' kz305 I test drove it and it seemed good
But the steering was a little wobbly. I thought it might be the old tire or loose bolts
So I've put new tires on it torqued all the bolts and I still have the problem
It's not loose wobbly but..... Tight i guess it just seems like it jerks over when
You turn the bars a little bit... Nothing seems to be bent either. Any help would be much appreciated..

Might try tightening the steering stem.