I have just traded for my first engine. An LA. I am having trouble with it not starting very easy. Like I have blisters after I am done. It wants to go but backfires and starts to roll backwards. I thought maybe the timing might be off so I re timed it. No luck. I don't hear an impulse click like my "A" JD makes. Never the less if I get gas to it , the fire is there. Anyone ever had a similar problem? After it finally starts it really pops hard when it runs. Is this normal? I thought it should be a little smoother. Like I said this is my first one and I am clueless here.