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Jetting Question (sorry)

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First off I know there is hundreds of jetting questions including a jetting sticky but everyones set up is alittle different and I have never rejetted anything. If you could please give me some advice on exactly what jets I need to change and to what size. Hopefully this is all the info you need, I have a bone stock 2005 crf450x with only 11 total hours on it. The only change ever made was I turned the fuel screw out 1 6/8 turns to help with idle. Im wanting to open the top of the airbox, do the stock exhaust mod, and the AP mod. I dont race I only trail ride between the altitude of 1500-5000 feet. What is the best jetting for this set up? Also, there is a bog if you open the throttle up quickly from idle but once your moving it accelerates great and sometime once it gets warm it wont return to idle like normal and seems to hang alittle? What would cause this? I know there are lots of questions here and you have probably heard them 1,000 times (sorry) but any help you can give me would be greatly appreciated! Thanks for your time.

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Open the top of the air box

Remove one stage of the muffler after the spark arrestor

165main

45 pilot

NCVS needle 3rd clip

R&D remote fuel screw, adjusted for highest idle (then drop idle with idle screw)

50 leak jet

Merge Racing apump linkage spring upgrade

That will fix everything

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follow Krannie's guidelines and your bike will RIP! You will not believe the difference when its done, like a new ride.

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I have the same year bike and followed all the above advice and it rocks. If I remember right I also replaced the gasket on the throttle valve to help with the hanging idle. Another recommendation from one of Krannie's or others older posts, don't use rubber cement though, I remember that much ;)

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I believe, going from memory, that my bike has the same setting that Krannie just posted. It runs really well with those.

The NCVS needle can be hard to dig up, it's an option for the early (maybe 2002) CRF450R bikes. So dig around in the online fiche's to find it.

The R&D Flexjet is really nice, I highly recommend it.

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The NCVS needle's part # is 16233-MEN-671

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Here's the Yamaha # and its less money than the Honda part #

5TA-14916-VS-00

Correct! The Kawi and Honda are both around $20-22 bux, and the Yamaha part number is $12.

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Thanks for all the help guys. Im having trouble finding the leak jet..does anyone have a part number? Where is the best place to order the jets from? Thanks again

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Thanks for all the help guys. Im having trouble finding the leak jet..does anyone have a part number? Where is the best place to order the jets from? Thanks again

http://www.jetsrus.com/a_jets_by_carburetor_type/jets_keihin_N424-52_leak.html

Not the cheapest, but it's one-stop shopping.

Most Yamaha and Kawi dealers stock Keihin parts.

High end watercraft from 2006 and before all used FCR 39 MX/CR carbs too, so they are usually the cheapest source.

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ok - I can jump onto this rather than start a new thread. 2008 CRF450X FMF Q4 J&D jetting kit, sorck airbox uncut, and pops back on decel... has a hard hit friend says it is lean. I think it is just super strong.... what say you....?

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ok - I can jump onto this rather than start a new thread. 2008 CRF450X FMF Q4 J&D jetting kit, sorck airbox uncut, and pops back on decel... has a hard hit friend says it is lean. I think it is just super strong.... what say you....?

Adjust your fuel screw with every change in air pressure.

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Open the top of the air box

Remove one stage of the muffler after the spark arrestor

165main

45 pilot

NCVS needle 3rd clip

R&D remote fuel screw, adjusted for highest idle (then drop idle with idle screw)

50 leak jet

Merge Racing apump linkage spring upgrade

That will fix everything

Thats my setup for about 2 years now, except the LeakJet, mine is a 55.

The part with adjusting fuelscrew:

It never did it that way with the R&D flex screw, so this seems to be a great help. But isn't it running too lean in idle with this setting?

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Thats my setup for about 2 years now, except the LeakJet, mine is a 55.

The part with adjusting fuelscrew:

It never did it that way with the R&D flex screw, so this seems to be a great help. But isn't it running too lean in idle with this setting?

Some use the 48 pilot (most).

My bike for some reason likes the 45 better.

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So if the bike pops on decel after adding an aftermarket exhuast (spark arrestor removed), airbox is uncut/stock and jetting is stock the bike is running too lean or too rich?

My bike has crank case vent kit and the emissions block off kit installed.

2009 450X.

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So if the bike pops on decel after adding an aftermarket exhuast (spark arrestor removed), airbox is uncut/stock and jetting is stock the bike is running too lean or too rich?

My bike has crank case vent kit and the emissions block off kit installed.

2009 450X.

Adjust your fuel screw.

Make sure it is not a tapered or aluminum fuel screw too.

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Adjust your fuel screw.

Make sure it is not a tapered or aluminum fuel screw too.

Open the top of the air box

165main

45 pilot

NCVS needle 3rd clip

R&D remote fuel screw, adjusted for highest idle (then drop idle with idle screw)

50 leak jet

Would the above setup work in 2500-4200 Feet above sea level and temperature ranges from 50 Degrees F to 85 Degrees F?

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Open the top of the air box

165main

45 pilot

NCVS needle 3rd clip

R&D remote fuel screw, adjusted for highest idle (then drop idle with idle screw)

50 leak jet

Would the above setup work in 2500-4200 Feet above sea level and temperature ranges from 50 Degrees F to 85 Degrees F?

Yes

0-6500 no sweat

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