ok i have a 97 sportsman500 i just had it rebuilt and bored out well i had a bunch of stuff done but no performance upgrades my problem is it will backfire wen i decelerate i dont know why it did it before it was rebult but once ina blue moon it would backfire now wen ever i decelertae from a decent speed like say 45 mph or even lower it will back fire i dont know why im think maybe the carb is loading up or somethin and i dont do work on my quad i have sent to my local dealer for work can you guys give me some incite on my problem please and thank oyu

 

maybe the valves arent adjusted right. usually back firing from slowing down is when the gas is built up and igniting.

 

is that something i could do myself or would i have to partialy take aprt the motor i mean i just put 1600 bucks in the rebulid i had it bored out to a 550 i put all new tires on i put new gears and stuff in the tranny so i really dont wanna put any more money into it rite now im trying to save for a new exahuast system cuz my can has a dent in would it help if i ajusted the fuel mixture? and would anyone know the top speed of a scrambler 400 2stroke and what kind of torque do they have

 

Usually backfires are associated with an exhaust leak. The leak gives it the oxygen it needs to ignite. Doc

 

i wonder where you bored it out so much if recalabrate the carb is in order. needs more gas, more air. hard to tell.

 

im not exactly sure if it was bored 50 over im just asuming they didnt tell me the had to bore it out to get rid of rust and they put a oversized piston in it because she siezed up i rode her today and tryed to get her to back fire but she wouldnt lets just say she would backfire on deceleration so i tryed to get it backfire call me crazy but i got her up to bout 55mph an promptly lay off the gas and hit the brakes and no backfire makes me wonder any ideas?