Looks like a Schwinn Racer / Collegiate as well. What's the badge say, the wheels may have been swapped but if it was a schwinn they would be stamped. Fork cap looks funny but it could just be grime.
There is no badge and the only place I found the word "Schwinn" was on the tires. I could not find any serial numbers anywhere. The forks look like the collegiate but the gap in the head tube between the cross bar and down tube is wider.
Schwinn-Schwinn and more Schwinn. It is SO Schwinn I can't even remember my own middle name...All I keep hearing is Schwinn. Wait wait--is this a prank...did I just get pranked??? Of course it is a Yamaha... I think it's one of Kenny Roberts prototype race models from the small era of factory Speedway pedal power races. In fact with some research you may find all 3 to be Yamaha --what I thihnk happened is someone with too many Schwinn decals has blighted these Yamaha bikes...my question...why??
First one screams Schwinn to me. The serial # will be on the left rear dropout (Where the wheel bolts on) Or on the steer tube. That will tell you what year it is and can narrow down what it is.
I never did find the serial number as it's too rusty. From talking to people at some bike events I believe it is a late 1960's Schwinn Racer. I replaced everything but the frame. Now I call it "Rusty Racer"