nosliw
03-15-2005, 07:33 PM
i'm stumped folks
my 400ex has been backfiring the last couple rides out and seems to fall on it's face right before it does. it does it when i'm in gear and just puting along probably in a gear too high for my purposes. but it doesnt do it all the time, it seemed like on certain areas of the trail it would happen. i downshifted when i probably should have upshifted just to wind it up and see if it did it, nope, dropped rpm and atv speed very well. i put it in nuetral, hit the rev limiter really quick, then went off riding and i think it made it a little better but i'm pretty sure it's all in my head. but before this has been happening i would drop a couple gears at a time and either hammer it or cruise right along with no problems. i checked for looseness of headpipes at head, on there tight. i changed the spark plug, perfect cardboard brown so i'm sure my jetting is good. she's got fresh gas. check tightness of the slip on to headpipe- nice and tight. i cleaned the carb a few weekends ago, shot carb spray through all the jets and cleaned up the float. i know that i did that right because the weekend after that i rode and it was perfect. then a week went by, found a new spot to ride, and it starts backfiring a little. it happened 3-4 times that weekend, then i did the headpipe torque-down and spark plug change and it only did it twice today. just before i got on my computer i backed the fuelscrew out 3 turns from lightly seated, but when i was screwing it in to seat it i think it went about 3 full turns anyway, so i dont think it was in too far or anything, it's got a 42pj also. also the backfiring occurs when i'm barely at 1/4 throttle.
here's some quick specs on the carb
152 main jet
eclip on needle in second position from bottom
42pj (3 turns out from lightly seated)
quad only has a hmf slip on, k&n filter w/ prefilter, stock airbox lid on
the wierd thing is i've had these same mods for about 20-25hours on the quad and absolutely NO falling on it's face or backfiring.
wtf? thanks to all who read it.
HELP!!!
my 400ex has been backfiring the last couple rides out and seems to fall on it's face right before it does. it does it when i'm in gear and just puting along probably in a gear too high for my purposes. but it doesnt do it all the time, it seemed like on certain areas of the trail it would happen. i downshifted when i probably should have upshifted just to wind it up and see if it did it, nope, dropped rpm and atv speed very well. i put it in nuetral, hit the rev limiter really quick, then went off riding and i think it made it a little better but i'm pretty sure it's all in my head. but before this has been happening i would drop a couple gears at a time and either hammer it or cruise right along with no problems. i checked for looseness of headpipes at head, on there tight. i changed the spark plug, perfect cardboard brown so i'm sure my jetting is good. she's got fresh gas. check tightness of the slip on to headpipe- nice and tight. i cleaned the carb a few weekends ago, shot carb spray through all the jets and cleaned up the float. i know that i did that right because the weekend after that i rode and it was perfect. then a week went by, found a new spot to ride, and it starts backfiring a little. it happened 3-4 times that weekend, then i did the headpipe torque-down and spark plug change and it only did it twice today. just before i got on my computer i backed the fuelscrew out 3 turns from lightly seated, but when i was screwing it in to seat it i think it went about 3 full turns anyway, so i dont think it was in too far or anything, it's got a 42pj also. also the backfiring occurs when i'm barely at 1/4 throttle.
here's some quick specs on the carb
152 main jet
eclip on needle in second position from bottom
42pj (3 turns out from lightly seated)
quad only has a hmf slip on, k&n filter w/ prefilter, stock airbox lid on
the wierd thing is i've had these same mods for about 20-25hours on the quad and absolutely NO falling on it's face or backfiring.
wtf? thanks to all who read it.
HELP!!!