My 850XP started to backfire before it just wouldn't start - it was just the plugs. Hope you have the same misfortune/luck. The plugs didn't look that bad either when I pulled them.

 

heres were iam at so far. i took the carb off and took all of the jet out, let everthing soaked over night. got it all back together and runs better, i now thing iam having a belt slipping problem i still dont fell the power like what i used too. when i punch the gas it still doesnt take off, its like i still dont have the power that i should. hope iam makeing some kind of sense

 

Check the ramp buttons on the secondary clutch, I'll bet they are worn.

 

ramp buttons? iam not sure what that is or were its at, i know were the secondary clutch is. is it behind it

 

Here is the 400 Mikuni Round slide Carburetor. This is the instuction to clean one.Disassembly and Cleaning of a Mikuni Round slide Carburetor

 

thanks for the help so far guys! will i need any special tools to pull the secondary off and any thing i need to watch out for?