Why is my YZ400F is idling too high?

I just removed the carb, cleaned parts, and re-assembled.

All settings were as before carb removal. Throttle has play, I tried to fully back-off the idle adjustment. Got any ideas, thanks!

What RPM is it running at?

your hotstart isn't sticking out?

I'd have to guess it's idling at 3000 rpm, and no the hot-start is not sticking out. (Choke's not out either.)

Cracked/spliced hotstart hose, dryrotted carb boot, loose carb clamps, and possibly loss of the small little oring on the fuel screw can all play a role in that.

Cracked/spliced hotstart hose, dryrotted carb boot, loose carb clamps, and possibly loss of the small little oring on the fuel screw can all play a role in that.

Jimbob69, thanks for tips. My old YZ has led a charmed life since new: climate controlled garage, low hours for a '99. (And this is how it repays me! I know, it's probably something I did but it's easy to pass the buck ain't it.) All the rubber parts are like new still, clamps tight, didn't mess with fuel screw. I will triple-check those things again though.

It's a really even high-idle; seems as though the slide is being physically held open. (Doesn't have a lean/uneven sound to it.) Could the needle be touching the main jet somehow? or possibly the metal-plate thing on the slide not be on just right and interfering somewhere?

I will have to dig in.

Make sure your rebound throttle cable isn't freighed and hanging up inside the cable guide just up from the carb.

Throttle cable was just a tad frayed, so I replaced that.

I discovered the problem: I installed the plate that "nests" in the slide upside down. :ride:

It's really easy to do; it even looks correctly installed when it's upside down. MY BAD!

Getting the slide out is somewhat of a puzzle, so now I'm getting better at it . . . should be good to go now, and thanks for all your tips. :thumbsup:

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