Having a **** of a time getting my 400 to run. Just put used oem cdi and fan controll, rectifier ignition. Finally getting spark, starter motor is shot so I've been pull starting. Every once an awhile I ca. Get it to caught like it wants to start but also sometimes I get a loud puff out of the carb intake. I looked at the valves and they appear to move as the motor rotates. Not sure why it's doing this, sometimes I get a clunk while it backfires out of the carb.