125-200cc tuning 09 wr125

I have started yard testing my wr125 and am having difficulties. it will lug pretty well at low rpm but as soon as I open the throttle it totally dies like it is running out of fuel. Kit needle, 450 main, #4 slide and I have gone all the way up to 50 on the pilot. Changing the pilot doesn't seem to matter. Airscrew at 1.5, I turned it in a little, didn't help. It does a little better if I am carrying some speed, but where i will be riding, I need to pull strong off the bottom. When it hits midrange, it seems to go rich, then runs perfect on top. Anybody experience anything like this?
GP

Hi, does the bike die when you wack the throttle?

Have you tried a smaller pilot jet? 32.5 or 30?

Also, check your plug.


JS

Sounds to me like a lean bog and I would try richening up the needle one clip and see how that goes.The pilot is your starter circuit so it's not going to have any affect with what you describe.
I have a '09 CR125 and stock it had what you describe and I went one richer on the clip and cleared it right up.

I agree with with riching up the needle. One clip position made all the difference in the world on my WR. It was falling on it's face, then became a rocket!

WR Bob

Yes, when I whack the throttle, it dies like I hit the kill button. If I roll on the throttle it is ok, but I think it is still too lean. I tried a 35 pilot the smallest I have, but the pilot seems to make no difference. I have also tried a new plug, and raising the needle. I want to check the reeds, but first have to find the right tool to remove those anti theft allen heads!
GP

I have the 1998 model but it sure seems to be pretty much the same by the exploded views. Perhaps I am all wrong but I have heard that those bikes for the european market have special exhaust systems with catalysts. They are put into the crate jetted for that special exhaust and some emission rules. They also put into the crates a kit to install in the carburetor designed to be compatable with the exhaust they ship the bike with. Is this true or a rumor? I know when I bought the 125 the dealer handed me a wrench for the axles and nothing else but a few years later I bought another bike from another dealer and got a plastic bag with a whole lot of stuff to change inside the carb if I felt like it. If you can contact the selling dealer with this in mind I would start there.

Fran

I'd richen the needle first, then I'd make sure the float level is spot on.

Beyond that I've had great success with a carb divider on the engine side of the carb in my 07, really wakes up the transition from the low end to the midrange. I can literally ride at 0-1/3 throttle all day if I want.

Today out of desperation, I drilled out a pilot jet with a .032 bit. Now it is a little rich, but the bike rips with good low end. I am not sure why mine needs such a big pilot, I need to check out the rest of the engine. I will order some bigger pilots and continue tuning. I am really excited about the potential of the bike now, don't need no stinkin KTM 300!
I am not sure where spot on is for the float level. Maybe since It has been lean, I will try raising it.
What carb divider are you using? I wasn't sure which side of the carb they go on.
GP

Water Racer,

Damn if you have to go that rich on the pilot I wonder if you have an air leak some where, base gasket, reed cage gasket, etc.

Walt

Power Now carb divider goes on airbox side of carb. '09 YZ125 application works. I tried running a 32.5 pilot on my '09 and definitely had a lean bog. My bike runs well with 45 pilot.
Throttle position and circuits involved....
0-1/8 pilot size, 1/8-1/4 how rich or lean the needle size is, 1/4-3/4 needle clip position, 3/4-WO main jet size.

I sprayed some carb cleaner around the carb and reed block while it was running, no difference. I think I will take a few things apart and investigate though.
Gotta remember, I am in a different climate, and it has been 35-45 degrees out, most of these jetting threads were done in the hot summer, and higher elevation.
I am just excited to know that it will run once everything is right.
GP