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Jetting kit for the wr250f

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Hi who will supply the most reliable jetting kit for a 2009 wr250 to get rid of this dreaded bog so many to choose from jd dynojet and more which do you all use thanks

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I do understand that they are not just a bolt in but it's been fiddled with before and been left worse I have managed to get it to pull clean ish once the throttle has been opened slowly to stop it Bogging

What's the AP ??

All the free mods are done apart from the Gray wire

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AP = Accelerator Pump, the mechanical diaphragm in the carburetor bowl that gets pushed on when opening the throttle, squirting some gasoline out of a nozzle and into the engine intake to prevent the bog you feel.

 

Typically, what's done with it is to make sure it starts to move at the right time (that the squirt of gasoline starts at the right time and lasts in duration for the right amount of time) and to make sure all passages are clear.

Parts of the carburetor are adjustable and replaceable in doing this (AP timing adjustment screw and leak jet).

A thick rubber O-ring is often used to tie the AP lever arms together to make the squirt of gasoline more immediate.

 

Once you look at all of the info both in your Owner's Service Manual and what is written on these forums, this will make sense to you as it's all basic Keihin FCR-MX carburetor tuning procedure.

 

Do the grey wire, too.

Edited by YZEtc

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Yes, the gray wire is on the list of 'must do mods'. You can slip the wire out of the socket, test ride the bike, see if you like the sharp response.

 

On my WR, I put a switch on the wire. I 'enable' the grey wire in very slippery/muddy conditions which makes for better 'bite'. To make this work, you have to shut off the bike, flip the switch and restart it. No 'switching on the fly'.

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Ok lads thanks I have ordered the j d kit but this will keep me busy for a while till the kit arrives from the US

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Well the Gray wires cut and what a deference it's made pulls harder and lifts the wheel in the first 4 gears with a bit of a pull also did the O ring around the AP thinks it's made a bit if difference but was hoping for a cure thanks for the help

Edited by Pete Thomo

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We'll I hope your all right as the postman has just delivered the jd kit so it will be going in tomorrow fingers crossed

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Riding a 08 WR250F, going to be uncorking as follows

 

Grey Wire Mod,

AIS removal kit (YZ  Throttle stop included)

Remove rear exhast internal baffle, Change exhaust external baffle

Remove Snorkel

AP Oring

R&D Flex Fuel Mix Screw

 

In the GYTR AIS removal kit comes a Main Jet and a Needle Jet.  Not sure what sizes they are.

 

Question is.  Do I really need to get the JD Jetting kit aswell??

 

I just figure no point spending the extra 100 bucks if the AIS removal kit jets will do the job.

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In the GYTR AIS removal kit comes a Main Jet and a Needle Jet.  Not sure what sizes they are.

 

Question is.  Do I really need to get the JD Jetting kit aswell??

 

I just figure no point spending the extra 100 bucks if the AIS removal kit jets will do the job.

No, you don't need to buy another brand jet kit if you already have the GYT-R AIS Removal Kit because, as you are thinking, it already comes with the parts to rejet the carburetor, especially the needle.

It IS possible you'll want to make some fine-tuning adjustments that the GYT-R kit will not include, like a different size leak jet or add a rubber O-ring to tie the accelerator pump levers together.

 

When I installed my GYT-R AIS Removal kit on my 2009 WR-250F, the bike ran well by simply following the instructions, and I rode the bike like that for over two years before (foolishly) selling it.

 

On the other hand, some guys will recommend you should still buy the JD brand jet kit because they are so much better, but that's something I can't vouch for.

Edited by YZEtc

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JD kits are the best but... you will stil have to adjust the carb. Kits are not 'bolt on and go' they get you close and it it is up to you to fine adjust. Did you read your owners manual about setting up the AP?

Jet kits are the biggest waster of money. There is nothing magical about them no matter how much they claim. Stock parts can and will achieve as good or better results. That is why there is a FAQ section. Save your money!

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On a 2008 WR-250F?

You'll be sorry.

At least, just make sure you don't ride one that was done with a jet kit.

 

The stock needle on that bike is a thick EPA needle that will not give good performance, but merely allow the bike to run while still passing regulations, and that's why the AIS Removal Kit comes with a different needle.

 

May as well not remove the throttle stop, too.  :)

Edited by YZEtc

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