Was Johnny Tran too hard on Jesse?
Yes, Jesse decided to race Johnny for pink slips in his beloved father's car and arrogantly called Johnny a fool for daring to race the Jetta with a "Honda 2000". However, Jesse is, well, different. Johnny should not have taken advantage of someone like Jesse. After the race Johnny should have said, "don't worry about it kid, I have larger pressing issues."
Yes, what Jesse did was dishonorable. It was shameful. It was rather pathetic, but Jesse is not like Dom. I believe if Dom had lost to Johnny, Dom would have honored his bet.