So what was it that caused the backfiring? Every piece of information helps others. Glad it's working OK, but please tell us what the problem was, and your solution, so others can benefit. That's how iboats.com works.
The reeds valve stops wre .350 high they were suppose to be .250 so I adjusted them to specs. and I had the spark plug wires backwards.
once readjusted fired right up after 5 pulls. sounded like a screaming eagle ran pefect. exellent power.