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tom nolan

Carburetor problems

2 posts in this topic

I have a 1998 YZ 400 with Idling problems. I took the carb all apart and cleaned it good and replaced the idle jet with a stock one. I set the neddle jet to 1 1/2 turns out from bottom. It seem that it can't seem to find a happy spot to Idle. First it idles really fast and than when I either pull the choke in and out really fast or pull the hot start in and out it seem to idle back to where almost quits. When I rev it up again it starts the fast idle all over again. I try to up the idle stop and than It wants to Idle too fast again. .I am trying to figure out what to do next. Has Anyone experienced this problem on there bike???

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I have a 1998 YZ 400 with Idling problems. I took the carb all apart and cleaned it good and replaced the idle jet with a stock one. I set the neddle jet to 1 1/2 turns out from bottom. It seem that it can't seem to find a happy spot to Idle. First it idles really fast and than when I either pull the choke in and out really fast or pull the hot start in and out it seem to idle back to where almost quits. When I rev it up again it starts the fast idle all over again. I try to up the idle stop and than It wants to Idle too fast again. .I am trying to figure out what to do next. Has Anyone experienced this problem on there bike???

Sounds like your fuel screw or as you said "needle jet" is set wrong. I had similar problems when it was set wrong. It was almost like it had a hanging idol. Warm the bike up turn up the idol some. Turn the fuel screw all the way in, then back out until engine rpms get the the highest point and stop. Then adjust idol knob back down to what ever rpm you want it at. done. The 1.5 turns out is just a suggestion in the book. If you have to go past 2.5 turns to get max rpm you need another sized pilot jet. if you go less than .5 turns out you need another sized pilot jet. Mine it right at 3.25 turns out and I have not fixed it with the right jet but it works fine until it one day backs out and fall out :devil:

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