Help me to not sell this thing 1999 YZ400F - hard start, flat spot off idle, pops at constant throttle (1/8 opening). Decel does not pop. I've been working on it off and on for a year or so, searched and applied all the jetting ideas for the stock FCR. Called Zip-Ty and they said they don't like to mess with the early FCR's. After many jets/screws/etc in the FCR I got it good enough to ride around for a day but I still had to throttle blip it to keep it from stalling. I bailed on the FCR and installed an Edelbrock. Power is great but all other problems are still same. I was able to address a lot of the flat/poppy spot off idle with pumpshot but at constant throttle it still popped and was generally unhappy - again at 1/8ish throttle opening. mid/high is great (if you can get it started, which right now, I can't). I puched a hole in my boot yesterday kicking it so it's close to finding a new home. Since I had the same issues with both carbs, I think carb/jetting is not the problem. I checked the valve clearances a long time ago and they were fine but I'm going to look at those again. Last night I pulled the plug and it was dry and kind of sooty with very weak spark. I swapped in a new plug and it's still a weak spark. I searched the forums and saw this is normal but cleaned up all the grounds and coil connections anyway - same spark. I haven't verified the cam timing and I don't yet know how to check the ignition timing. Tried to find a manual download but couldn't for the 1999 YZ400F. Still looking. If this were an old car, I would be looking at ignition timing bouncing around just off idle. but this isn't an old car. Also I was thinking of putting an 02 sensor on there just to see but I've been through both carbs SO MANY TIMES.. I'm kinda done with that at this point. Plus I'd have to kick it again so... Anything I'm not seeing? Any fresh perspectives that see something obvious I'm missing? I don't want to sell it but my foot hurts. I keep thinking "WR....'Lectric start...mmmmmm". I would like to take the "one thing at a time" approach and get it right. Thanks for the help and sorry for the long post.