02 CR125 Flat Spot

I just picked upan 02 CR 125 and noticed it had a flat spot in it. You have great response from closed to 1/4 throttle. You go from 1/4 to 1/2 or 3/4 and there is a flat spot that you have to feather the throttle to get through it. Once you get through it, it will put you in the power band and pull hard. My question is how do I fix it.

So far I have taken the carb off and made sure it wa clean. Also I saw that the jets were not the correct ones. I have a Pro-Circuit Works headpipe and Pro-Circuit R304 Shorty silencer on it. It had #410 main, 35 pilot and needle clip in the middle. On Pro-Circuit's website it says it should have #390 main, 32.5 pilot, and needle clip in the middle, air screw 2 turns out. I changed the jest to Pro-Circuits specs. Also it has a new top end and new Boysen Reeds. I also tried changing the needle clip up and down and putting it in the second notch (richer) it runs a touch better than the middle but not alot, still have a flat spot. Next I am gonna check to see if I have an air leak around the reed valve. Is there anything else I can check or try to do to get rid of that flat spot? Should I mess with the air screw some more and try that? If anyone has any ideas please let me know. Also I am at an alttitude of around 2000ft. Also my needle jet is 6DFY5-74. On Pro-Circuit it calls for a 6DFY-74, are these needles the same ones? Thanks in advance to anyone with some answers.

I am pretty sure Pro Circuit's jetting recommendations are based on sea level at around 70*. So, if anything, that should just be a base line for you to get started with. You will still need to adjust to your own particular area.

Air screw won't do anything for jetting the mid range RPM's, it works in conjunction with the pilot jet.

here is MXAs specs:

2002 HONDA CR125

Mainjet...stock

Pilot jet...30

Needle...stock

Clip...3rd

Air screw...1 1/2 turns

Play with the needle clip more.

Right now the clip is in notch 2. The bike starts up and idles great revs up nice in neutral, just has the flat spot in the middle. When at sea level which way do you go when you are higher? Do you have to lean or richen the bike if you are around 2000ft? The bike has alot of top end power if you keep it there, I would just like a smooth transaction instead of a bog then full power. The wheel comes up pretty fast if your not ready for it lol.

Also forgot to mention that I am not sure what his fuel mixture is too. I know he runs Castor 927 but dont know his ratio. Also it is getting low on fuel so I need to take those two things out of the picture when I put fuel in it.

Well I did some more riding around yestereday before I ran out of fuel. If I open the throttleat a slower rate, instead of cracking it open it will somewhat go smoothly through the transaction. I will mess with the needle clip again and drop it all the way to the bottom and see if it helps. If anyone else has any suggestions please let me know.

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