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The joys of jetting

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Hey guys,

New around here and glad to find the site. For all you jetting gurus out there, I just installed a Moose jet kit. Needle clip is 5th from top, cj136 main jet, and fuel screw is 2.5 turns out. I am running stock exhaust with a PMB high flow spark arrestor, stock baffle removed. Running elevation is around 4000-6000ft. Bike had horrible sputter on decel when I first got it. Kit may have tamed it a little bit, but not too much. Any ideas on what might be causing the decel pop?

I recently bought a Moose fuel screw in hopes I might be able to "tune by ear". Think this might do the trick?

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If it sputters on decel that typically means a lean running conditions.

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The air injection system will cause popping on decel. There is a $35 kit you can buy to plug the hole in the cylinder-head after you remove the AIS.

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^^^ Agreed.

that is a pretty lean MJ. Try putting the stock 145 back in and see how it does. Maybe try a 150 as well.

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Do the high-altitude bikes come with a smaller pilot from the dealer? I just assumed you are running a stock 45. Mine idles perfect and doesnt pop with a 48. But Im at sea level

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does the moose jet kit use keihin main jets?

what do you mean " cj136 " main jet?

hard to believe they would give you a 136 jet when we all run 160-170 mj

I think there was a company "F2" maybe that used a main jet adapter and different jets

not sure why anybody would go that route as proper keihin jets are cheap

they may design their own jet needles also to work with their jets?

I have a JD red needle and the NCVR stock KX needle and both work good.

good luck .....

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No the moose jet kit uses the dynojet style adapter and main jets. And I agree its better to use genuine Keihin jets.

I figured out last night that I can change the main and pilot in 10 minutes without removing anything except the chain guard. All you need is a 17mm, a 6mm, and a small flathead socket bit in 1/4 drive along with a u-joint adapter and 6" extension for your ratchet. This really saves a lot of time and hassle versus stripping half the bike to get to the carb.

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No the moose jet kit uses the dynojet style adapter and main jets. And I agree its better to use genuine Keihin jets.

I figured out last night that I can change the main and pilot in 10 minutes without removing anything except the chain guard. All you need is a 17mm, a 6mm, and a small flathead socket bit in 1/4 drive along with a u-joint adapter and 6" extension for your ratchet. This really saves a lot of time and hassle versus stripping half the bike to get to the carb.

EXACTLY how I do. No need to remove the carb!

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168-170 main

KX NCVR needle on the 3rd clip (from the top)

45 pilot

Stock exhaust with promoto billet end cap and sparky.

Remote mixture screw.

I also shaved the accelerator pump diaphram stop, tweeked the spring (not the oring mod that rots), and changed the pump timing.

AIS removed. Bike runs great and never overheat in the woods.

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Anyone know if FCR jets and two stroke PWK jets are interchangeable? Same number sizes.

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Anyone know if FCR jets and two stroke PWK jets are interchangeable? Same number sizes.

.

They are, and same numbers, helps to have one set of jets for both my bikes, kx500 and klx 450:)

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168-170 main

KX NCVR needle on the 3rd clip (from the top)

45 pilot

Stock exhaust with promoto billet end cap and sparky.

Remote mixture screw.

I also shaved the accelerator pump diaphram stop, tweeked the spring (not the oring mod that rots), and changed the pump timing.

AIS removed. Bike runs great and never overheat in the woods.

Thank god, finally someone wrote his jetting settings.

Just wanted to ask you, at what altitude and temperature do you ride?

(I have read, that quite a few of you guys are using KXF exhaust - can somebody PLEASE tell me, how does the KXF exhaust affect on the running of the bike - does it run even leaner, etc? And if it does, what kind of jetting correction's have to be made?)

Edited by theBillSLO

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Thank god, finally someone wrote his jetting settings.

Just wanted to ask you, at what altitude and temperature do you ride?

(I have read, that quite a few of you guys are using KXF exhaust - can somebody PLEASE tell me, how does the KXF exhaust affect on the running of the bike - does it run even leaner, etc? And if it does, what kind of jetting correction's have to be made?)

. Not sure what the big secret is. I would rather ride with someone with a good running bike that can keep up than someone that is overheating and pissed because his bike is not running good. Running sea level to 6000'. I also unhook my gear shift sensor when it get in tight woods or higher elevation so I retard on timing and don't chance over heating when I am working the crap out it. So may disagree, but they don't ride my bike now do they:)

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Which of the following two main jets is the right one for the Keihin FCR carburetor of my KLX 450R 08? The regular or the long one?

http://www.ebay.co.uk/itm/Keihin-FCR-CV-CVK-PD-VB-VE-VA-Main-jet-99101-393-170-/250990615441?pt=UK_Motorcycle_Parts&hash=item3a7034db91#ht_814wt_905

http://www.ebay.co.uk/itm/KEIHIN-Main-Jet-Long-Hex-CR-FCR-PJ-Motocross-Enduro-168-/290746824965?pt=UK_Motorcycle_Parts&hash=item43b1dc7905#ht_691wt_1185

crazyal426, where did you get your NCVR needle? There is not a single one on the whole e-bay??! Even google has very few results for this needle... :)

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Which of the following two main jets is the right one for the Keihin FCR carburetor of my KLX 450R 08? The regular or the long one?

http://www.ebay.co.u...91#ht_814wt_905

http://www.ebay.co.u...5#ht_691wt_1185

crazyal426, where did you get your NCVR needle? There is not a single one on the whole e-bay??! Even google has very few results for this needle... :)

The second one is the correct one. with the hex head. The needle is OEM, search 08 or 09 kx 450 and it is in the carb breakdown as an option.

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Thanks a million man, we did everything as you instructed, bike works like a charm.

It uses more gasoline, but that was expected due to larger main jet, and it is a little louder (KXF exhaust), but everything else is just great. A lot more power, throttle much more responsive, less overheating, very satisfied with it.

I guess the big secret of writing ones jetting settings goes something like this: "if I had to buy a jetting kit for 80$, no way that I'm giving you settings for free, so you can fix your jetting for a few bucks. Go buy yourself a jetting kit and spend as much as I have spent to fix my jetting..." Very sad way of thinking <_<

Thanks again Crazyal426 :thumbsup:

Edited by theBillSLO

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Great to hear! Too bad you are a little far away to go riding with. Keep it ripping all the same.

Alex

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