400EX help
#1
05-30-2018, 08:21 PM
400EX help
Hey guys I’m new to the site I have an ‘07 400ex only mods are jet kit, k&n air filter and HMF exhaust. The problem I’m having is that it’s VERY cold natured. It doesn’t wanna idle at all and I can hear a light knocking sound but when it warms up everything smooths out and runs fine. I can ride it for an hour or so then let it sit for just a little while and it’s like it’s cold all over again. I’m kinda thinking the jet kit may have something to do with it the previous owner done the jets so I have no idea what size they are. I would greatly appreciate any input u guys have. Thanks
#2
06-03-2018, 10:35 AM
Country Rider
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Location: Michigan
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Hey guys I’m new to the site I have an ‘07 400ex only mods are jet kit, k&n air filter and HMF exhaust. The problem I’m having is that it’s VERY cold natured. It doesn’t wanna idle at all and I can hear a light knocking sound but when it warms up everything smooths out and runs fine. I can ride it for an hour or so then let it sit for just a little while and it’s like it’s cold all over again. I’m kinda thinking the jet kit may have something to do with it the previous owner done the jets so I have no idea what size they are. I would greatly appreciate any input u guys have. Thanks
Does your quad always idle bad? How does it do starting up? If it starts kind of hard and always idles bad, clean the carburetor and adjust the pilot jet size.
#3
06-06-2018, 08:47 PM
I aggree with YamahaMoto.... Definitely sounds like a carb issue. If I were you I would take apart the carb and look at the jet sizes... Change the spark plug and that will tell you if your rich or lean. Look at your jet sizes and go from there... I suggest going with a 42 idle and a 165 main. Air fuel.... 2 3/4 turns out. and the needle on the 3rd notch from the top. The ticking is your valves but I would not be worried about that as not as its not too loud. (normal on a 400ex)
#4
06-20-2018, 08:48 AM
I’m back lol
Ok guys I decided to clean carbs and go up to a 42 pilot jet and while I was at it I adjusted the valves and now it runs ok but when going from idle or low rpms to full throttle it bogs and I’ve noticed it’s blowing air out the air box when I give it throttle it’s enough to lift the air box lid if I don’t strap it down. It’s also running rich it turns the plug black and it’s the factory 148 main jet just make no sense. I’ve went thru the carb 3 times to make sure everything is right and I’ve readjusted the valves tight, loose, just right and nothing seems to make a difference. I also done a compression test and it’s good 120psi so I wouldn’t think it’s a valve. Please help!!
#5
06-20-2018, 09:40 AM
Supersock
Hired Gun!
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Hired Gun!
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#6
06-20-2018, 11:16 AM
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