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MaddogYZ

AIS questions

6 posts in this topic

Hi guys, new member here and a new WR owner as well. I recently bought an 05' WR450 that has a JD jet kit installed and the throttle screw replaced. I've been reading up on the "free" mods for the WR's for a little while on here and in magazines and I want to do them to gain some extra punch down low and get rid of the lazy throttle response. Coming from a YZ250 the WR lacks that hit that is so addictive :banghead:

So assuming I remove airbox snorkel (i'm not going to cut holes in the side of the airbox though), clip the gray wire, and buy the AIS removal kit from Yamaha , how f'd up is my jetting going to be? Looking at the pictures on yamaha's site it looks like the AIS kit comes with some extra jets, so does that mean my JD kit will be spitting and sputtering or will it be good with maybe the exception of the pilot jet? Just looking for some personal experience from you guys and any info is appreciated.

Thanks! :busted:

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The AIS kit removal won't have a dramatic effect on your jetting. If anything, it'll just get rid of any backfire that you have on decel. The snorkel removal, and airbox holes are going to screw up your jetting. My guess is that you'll have to swap out your pilot, main, and leak jets after altering your airbox - depending on what type of exhaust you've got.

check out the jetting database in the performance index, and you'll find some good guidance on where to start out.

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All the AIS does is inject air into the exhaust. This air assists in consumming unburned fuel in the hot header. It does not affect jetting whatsoever. Removing it means less weight and less crap to deal with. The AIS kit from Yamaha comes with the YZ throttle stop screw and a needle and a few mains, I think. You do not need these parts. Look into the F2Racing kit instaed. It is a much cleaner kit and coses up the port in the head with a much nicer method. Just be sure you have all the parts before you start the job. A few people have had poor jetting then using the carb parts from the Yamaha AIS kit.

Removing the snorkel and cutting the airbox will affect jetting. I hope the seller gave you the left over parts from the jetting kit. Sort of suprised it 'has' a JD kit installed and the airbox is still stock.

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The AIS kit comes with several types of jets not just several sizes of a few jets. In other words it rejets the whole carb. It is well worth the time and effort to remove and redo the carb.

G2

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