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Rejet w/o AIS removal

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I have an 08 WR250F. I can't seem to find an AIS removal kit. Can I rejet with a JD jet kit and leave the AIS alone? Is there any other reason to remove the AIS besides the slight weight savings? Thanks for any help.

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Yes you can use the JD kit without removing the AIS.

But that's an easy kit to find. Order this kit online or from your local dealer: GYT-5UM93-69-01

http://www.yamaha-motor.com/sport/accessories/acscitemdetail/5/66/55/2301/2008/all/6228/0/detail.aspx

It's easier to work on the bike if you remove the AIS. There's really no performance difference power-wise with it on or off. I'd remove it for the weight savings and ease of maintenance if your state doesn't require it to be installed.

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Yes you can use the JD kit without removing the AIS.

But that's an easy kit to find. Order this kit online or from your local dealer: GYT-5UM93-69-01

http://www.yamaha-motor.com/sport/accessories/acscitemdetail/5/66/55/2301/2008/all/6228/0/detail.aspx

It's easier to work on the bike if you remove the AIS. There's really no performance difference power-wise with it on or off. I'd remove it for the weight savings and ease of maintenance if your state doesn't require it to be installed.

AIS does not affect the jetting at all.

All AIS (Air Injection System) does in inject air into the exhaust to dilute it.

Thanks guys, just what I needed

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You don't really need a kit to take it off. All you'd need to do is go buy 2 rubber plugs (1 big one for the airbox and 1 small one for the little nipple) from an auto parts store for about 50 cents, and thread the metal tube and put a 50 cent nut on it...

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You don't really need a kit to take it off. All you'd need to do is go buy 2 rubber plugs (1 big one for the airbox and 1 small one for the little nipple) from an auto parts store for about 50 cents, and thread the metal tube and put a 50 cent nut on it...

True; all you need to remove the AIS is maybe $2.00 in parts. The GYTR kit includes new pilot, main, and leak jet (depending on the kit), a YZ needle and YZ throttle stop, and some plugs and a tie wrap or two. If you haven't already changed those parts, you can kill a couple of birds with one stone and save some $$ overall. :thumbsup:

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Hey David,

Great advice mate. Having the exact same problem with my bike. Has that throttle bog real bad soon as you rap it on round tight corners or trees for that matter. Very used to my old YZF always pulling me out of a bad situation with its serious aggresion, but the WRF i just bought doesn't have any of that. It just dies when you give it to much. Will call my local dealer about the Jetting kit GYT-5UM93-69-01. I'm hoping this is the remedy because so far i've been pretty disappointed with the bikes pick-up. It already has a GYTR exhaust, could possibly be that the previous owner didn't re-jet after the mod. Got me buggered. But i gotta race it this Sunday which at the moment i'm really not looking forward to.

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YW. Look up the o-ring mod, Ash_88.

Basically, slip a small, thick o-ring over the Accelerator Pump spring and AP lever to pull them tight together. That, combined with a #50 or #55 leak jet should fix that throttle bog. (some people go as low as a #40, but larger is better IMO for things like woops and bumpy trails)

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