i went out today and for some reason the carb when to backfireing and its also down on power

 

check main jet and slow jet for dirt

 

do you have a link on the carb diagram

 

What are you having trouble with 4 stroke or 2 stroke

 

2 stroke its a sportsman 400

 

possibly an air leak too. if the carb doesnt fix it check your crank seals

 

o boy are the crank seals hard to replaces?

 

I am by no means an expert on this problem,just bought a 400 srambler and only a weeks worth of study on this engine, but I would look at the reed valves. You would do well by trying a search for your problem or being patient and someone more knowlegable than I will set you on the right path.

 

i have google everthing on the sportsman and all i get is info on the 08 ir newer sportsman

 

First thing I would do is try a new spark plug - then dis-assemble and clean the carb.