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Please Help on 05 CRF250R Jetting

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Brand new bike...Like the current gearing setup so I am sticking with that. The bike pulls great in mid range and top but is sluggish coming out of corners(even when I added one tooth-just basically lost mid to top when I did that). It just won't get up and go out of corners. I am running completely stock settings. 172 main, 42 pilot, 1 3/4 turns out. Do I need to lean it out or go up to a 175. I am running the backfire screen but will be changing that tomorrow to the twin air cage and filter. I am located in Atlanta Georgia Area with elevation between 700-1100 and right now the weather is between 56 or so at night and 70-76 during the day. The manual shows I am where I need to be but something just doesn't feel right. What do I run to make this thing run stronger off the bottom? Like I said, mid to top feels fine. Thanks for any help you can give me.

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Alright, put the twin air and didn't notice any difference between the backfire screen and twin air. Doesn't bog but just lacks bottom end kick or torque. Before I go leaner, I have the power now and power now plus that I am thinking of installing. Should I install it or is it just a waste? I am thinking of just returning the power now system but want honest opinion if it will help at all. Would going leaner accomplish the same thing as the power now plus system or would you recommend slapping it in and staying at stock jetting?

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The Power-Now will richen the jetting for low-end torque. You will trade off some top-end for more low end. It's your decision to make.

You might want to try a richer needle clip position setting as an alternative, keeping the fuel screw setting a little further in.

James

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JD,

Same problem as above, though I'm not going to a Powernow. So you would say a 170 MJ? 168? I had read pc's recommendation of 162. Too much? Also, what about the fuel screw to 2 turns out? I took the backfire screen off, but haven't ridden with it off, yet. My wife's bike is noticably stronger off idle, so I don't think it's just me adjusting to a 250.

My first thought was to go 1 clip leaner on the needle. I'll be glad if I don't have to disassemble the bike to get to the top of the carb!

Thanks!

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So you would say a 170 MJ? 168?

Try a #168 and compare.

The needle can be accessed with tank and seat off using the crf needle removal tool. Loosen the carb clamps to rotate the carb slightly (left/right) for access.

See- Needle Access

Needle Removal

James

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JD, how does leaning out the MJ make the bike more responsive? doesent the main affect the upper end of the powerband? And why leaner if you take out the backfire screen, with more airflow shouldnt you go up on the MJ? thanks in advance.

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Yes, this is aimed at the upper end of the power-band.

There is a little background to look at here. The stock '04 CRF250R ran a #160 MJ and most aftermarket pipe makers recommended a #165 for more response. In '05 Honda went much bigger to help bottom-end power and has a #172, which seems excessive overall with the stock needle and bigger pilot jet. I don't expect a #175-178 would help in this case (too rich) with stock needle, so the estimate is to try for more crisp jetting with a #168-170 which is slightly more than the #165 to adjust for a more open air filter.

James

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Am I reading this correctly??? To achieve the same results as a powernow one can adjust the jetting to be slightly richer on the pilot and needle diameter? That's all a powernow does is pull more fuel at small throttle openings? If that's the case then I can see and understand the advantages of the custom needle tapers.

Question #2

The JD kit for the 2005 CRF250R, are there different settings when compared to the 2004? Did the head and map changes require different settings?

Thanks

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James, You recommended below settings which I have been running. Should I try leaner settings or have you tweaked this a bit?

05CRF250R

sea level, no backscreen

Red needle, 5th

42 PJ- stock

180 MJ

1 1/2-1 3/4 fuel screw

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The stock '05 jetting is richer than '04, but the kit instructions were already suggesting this change.

MMotohead,

Use the 180MJ for more low-end and mid-range at full throttle. Make sure it revs out, and if you want the top-end to rev cleaner, lower the main jet back down to a #175-172. I would try both and decide which setting better suits your conditions and how you ride.

James

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Ok. I will try both. Why does a bigger main run cleaner low and mid at full throttle?

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