why do you suppose this yz is doing this? vid

does this little stutter thing right before it hits the pipe

def got a little studder, is it fouling plugs , splooging, smoking bad?

Did you check the plug?

nope, none of the above, and the plug is that sweet light brown/grey

that sounds rich to me, did you try moving the needle down 1 clip? if not, try that, it is quick easy and will make it better or worse.....for example, if it is on clip 3, move it to clip 4 (from the bottom) ..... or 2 from the top..... the plug can look good if the main is good and your not idling around on it....

mmmmmm. ya, when i did the plug pull it was from wide open throttle, under load, pull the clutch and hit the kill at the same time. so, you think i should get it to that stuttery spot and kill it there and pull the plug?

and i'm on the next to the top now

I'm with spinner , sounds like it's running a little rich .. Sounds loaded up right before it comes on the pipe .. Ride it normal then pull the plug .. It'll probably read a little different than doing it the way u did in your last post..

Air filter clean? I'd agree, sounds off a bit. Almost sounds like it never gets up to temperature....how's the condition of the pipe? How old is the packing in the silencer?

needle diameter too rich.or slide too rich.have had same stutter.slide cut fixed it.

easiest thing to do is change the clip on the needle, really only takes 5 minutes you can do it with the carb in the bike....dont worry about the plug.......change the needle and see how it runs....are you running the ew needle? that is rich off idle might have to use the ej needle......

Check that the powervalves aren't stuck shut too.

just did a new power valve, was in a bad way and was hoping it was going to go further to solve this, i think a hand full of jets and a weekend of screwing with it oughta help

I have had a similar issue before. It was caused by a rich needle position.

Just thought of something.....when I bought my '03 YZ, it had the WR gears 3-5th, and a home made skid plate on it....it was having a TOUGH time getting on the pipe in 5th. I figured it was jetting or timing....when I pulled off the skid plate, I found the plate mounted to the frame had pinched the power valve vent/drain tube. When I rode it without the plate, it pulled 5th with 0 problems, and also puked out a pretty good amount of sludge from the drain tube....

Just a thought....

def rich, def the needle, I had the same problem when I got my JD jetting kit. The needles in those kits are extremely sensitive to ambient conditions and jetting, but they do make the bike haul ass.

If it's your stock needle, they aren't as sensitive, but either way, you'll want to raise the clip one or two and get back to us on how it performs.

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