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jmarnott

09 WR 450 backfires on deacceleration

14 posts in this topic

I have noticed that my bike backfires when I let off the throttle. Is this a normal happening with these bikes?. As far as jetting I have a JD kit installed follow all the settings for my weather conditions.

Thanks for your help.

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I have noticed that my bike backfires when I let off the throttle. Is this a normal happening with these bikes?. As far as jetting I have a JD kit installed follow all the settings for my weather conditions.

Thanks for your help.

Did you remove the AIS (air induction system, you know, smog crap)?

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No it should not backfire on decel. Check your header bolts , could be sucking in cold air .

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This is from the FAQ section of the WR450 mods. It is in the "stickies" at the top of this section.

I never rode my bike with the AIS on so I don't have first hand knowledge. It was the first thing to go along with the addition of the JDJetting kit and FMF slip-on exhaust.

Q: What is an AIS?

A: AIS stands for Air Induction System, i.e. the smog pump. It injects air into the exhaust system to help get rid of unburned fuel for a more environmentally friendly bike. It first showed up in '05 and has been on every WR since. It can be removed and the resulting holes plugged if you buy either the TT Kit or the GYTR kit. The TT kit has precision machined plugs that press fit into the engine, while the GYTR Kit’s plugs are removable and also include an adjustable needle, throttle stop and assorted items for the carb. The AIS removal DOES NOT improve performance, but it does decrease decel popping so you can more effectively jet your bike.

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Yeah I put on my DRD exhaust along with the JD jet kit before I removed the AIS and it was popping like crazy. I installed the GYTR AIS removal kit and and no more popping.

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On my bike I did all of the free mods(air box, throttle screw, gray wire unhooked) . I did notice that I will get a little less popping on deacceleration with the gray wire unhooked.

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Thank you for all the information.. I will give the gray wire a try and then move to the AIS removal.

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If you pull the AIS, the popping on deceleration will decrease significantly. At least it did on my 2009 :crazy:

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The gray wire has F.A. to do with decel popping. The AIS allows air to enter the exhaust , after the valves, on high vaccum decel situations and the air that enters into the exhaust at this point can re-ignite some of the unburned fuel in the exhaust system at this point. The AIS is there to allow air to enter with the exhaust so the bike will pass emmisions testing. Removing it, as stated , doesn't help performance , but it does make jetting easier and greatly reduces the popping in the exhaust. By all means do the grey wire mod as well though. WR Dave.

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The gray wire has F.A. to do with decel popping.

Tell it like it is, Sir!:eek::crazy:

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Sorry SXP, I had an extremely trying day teaching mechanics yesterday and the misinformation was starting to work my nerve a little. I'm better now. :crazy: WR Dave

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I did the AIS removal last week, it seems to take care of the deccel poppong! But I was following directions on the grey wire removal, But I Didnt see a grey wire in the harness it said it was supposed to be in! :crazy:

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