Newbie trying to get a 79 50v running. Just replaced the head, base, and exhaust gaskets, and cleaned the decompresser. Gave it a crank and it starting backfiring like crazy but didn't start. This is actually the closest to having life that it has ever shown. I readjusted the timing, and now nothing, except suddenly i can hear a strong hiss coming from the dellorto clone carb. Cleaned that but well, nothing.