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How do you know when your Jetting is just right?

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So i've been working on this FCR carb on my yz250f ever since I got it. It had hot start problems, bogging, stalling, poor power etc.

So I think i finally figured out the jetting that it needed, has new needle, 40pilot and 175main. For first time ever it starts hot with a single kick and performes from idle to WOT almost perfectly. If it's in high gear going slow and I want to build rpm slowly across the powerband it will occasionally bog and try to stall, I really have to be picky to get it to do this by tractoring in 3rd gear, but it still bothers me. I want it to be perfect at all rpm all throttle positions. Am I just being too picky? When do you decide jetting is "good enough"?

 

 

 

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Stock should of been a OBEPQ, leaner at wide throttle openings and richer at small throttle openings. I'd source a NFPN.

A lot of guys love the 5TA-14916-YS-00 (#NCYS) But they are MX riders.

Remember too, you have a race MX bike and it is not designed to tractor. It is supposed to be run at 5,000 rpm and up.

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yeah but except at that 1000 RPM band just before it gets on the pipe the engine should run clean with correct jetting.

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Hum, well I can always  experiment with different needles, they are cheap. I know i'm getting very close with the jetting. 

Im shocked at how different these small 4 strokes change before and after they are warm. When I went to test after making some changes to the clip position this last time, I thought it wasn't going to run well because it kept stalling before it was warm enough. It would bog and stall 2 or three times when I'd get on it before it reached full temp. Soon as it was at fully warmed up  it was running great, but not a minute before.

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Dig in to the accel pump circuit and get that sorted.  Had all kinds of trouble with mine till I figured out the AP.

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On 5/22/2017 at 8:45 PM, William1 said:

. I'd source a NFPN.

 

What is the difference between he NFPN and the NFPR (stock) i'm running now and why this recommendation? 

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13 hours ago, xtactical said:

 

What is the difference between he NFPN and the NFPR (stock) i'm running now and why this recommendation? 

Slightly richer on the straight diameter (between 1/8th throttle and 1/4-actual throttle position, not rpm)

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