AIS kit jetting too rich?

8 replies to this topic
  • mvryder

Posted March 06, 2008 - 02:14 PM


I have been reading the jetting database and I still have a question. I am running the AIS removal kit jetting. What do you think of this? Too rich? I know based on what a lot of people are using this is pretty fat at 175-50. I am not sure of the needle because it seems that most are using some JD needle and I don't know how this compares to the AIS kit needle. Also I am not sure how the other jets in the kit effects the hole picture. So those of you using the AIS kit....what have you changed since that?

I ride a 07 wr450 in Southern cal 1000'-7000'. I run the stock pipe with the inner most baffle removed (the one that need the rivets drilled out to remove).

  • WR450RICKO

Posted March 06, 2008 - 05:46 PM


I have the 06' and the only thing I have done in addition to the GYTR AIS Removal kit is put a Zip Ty air screw in and turned it out 2.75 turns. Dyno indicated this setting for optimum. If you ride above 4000' regularly, 2 turns probably will work better.

  • William1

Posted March 06, 2008 - 06:36 PM


If running a stock exhaust, a 175 main is about right at sea level to 1,000'. Above that, you should run a smaller main to about 5,000, than a smaller main again above 5,000. Each time you put in a smaller main, you should move the clip on the needle one position closer to the flat to lean out the mid range to match.

  • mvryder

Posted March 07, 2008 - 07:32 PM


do you mean move the clip up (lower the needle) or move the clip down (raise the needle)?


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  • alburito

Posted March 08, 2008 - 09:10 AM


On my 08 wr 450 i used the gytr ais kit, it does seem to run a bit fat, it likes the gas, but overall it runs aswesome, too much work to re do so i am leaving it alone.

  • dirtysouth

Posted March 08, 2008 - 09:29 AM


I dunno for sure as I am no expert but that sounds fat to me. I ride an '05 with AIS gone and stock can/pipe from 0' to 3 or 400' most all of the time. I have been running a 160MJ and 45PJ with great results down here when temps are in the 80-100 range..Needle's a red JD on 5th cp. I just now opened up the exhaust by removing a baffle and so now I am gonna move to a 162 and see whats up. INDY recommends a 165/48 but I think that the 162/45 is gonna scream on the way up. The biggest I have ever gone with good results here is a 165 in 30-50 deg weather. 168 and 170 didn't work as well but these carbs require more than a MJ change to show off anyway. Try stepping down to a 165 and see what you think about it up top. Might try the OEM pilot with it and set the needle a little thinner. Just my opinion though:thumbsup:

  • William1

Posted March 08, 2008 - 09:44 AM


do you mean move the clip up (lower the needle) or move the clip down (raise the needle)?


Moving the clip towards the flat (flat/top of the needle) to lean (lower the needle) as you go up in altitude. Less air density = Less fuel needed.

  • BajaFool

Posted March 08, 2008 - 10:52 AM


Below are my comments on your jetting issue. They are excerpted from an earlier discussion thread on this same subject.

What follows is the excerpt from the October 2007 Dirt Rider 450 shootout article entitled 2007 450 Off-Road Comparison: "Making the Yamaha Run. It is pretty easy to make the WR go from snore to score. Just buy the GYTR kit (GYT-5TJ93-69-01, $49.95) that includes the shorter throttle stop, a block-off kit for the Air Induction System (AIS) and a set of jets that bump the power by richening the jetting, then follow the included instructions. This is how we tested the bike in Costa Rica for its debut and in our first test. But in light of current standards and enforcements here in California, we also came up with the setting that we tested the bike in for this comparison. We used the shorter throttle stop, took out only the smallest stuffer from the muffler and removed the restrictor from the top of the airbox. We also disconnected the gray wire at the six-pin connector underneath the left sidepanel. We left the stock jetting in the bike and did not mess with the AIS, as it has no performance effect on the engine aside from causing the lean popping noises inside the exhaust. With this setting, we felt the bike was more ridable and smoother in the smaller throttle positions than the GYTR-jetted bike, and it got better fuel economy. Plus, it ran better at elevations above 7000 feet."

Finally, leaving the stock jetting alone as mentioned in the article would seem to imply that the stock needle was not changed. However, I would still get rid of the AIS, if you want to go with the Dirt Rider recommended jetting, because listening to it pop is annoying and may cover up a lean jetting problem.

Finally, finally. The SEARCH function is a great tool on Thumpertalk.:thumbsup:

  • esbotto

Posted March 08, 2008 - 08:11 PM


On my 08 wr 450 i used the gytr ais kit, it does seem to run a bit fat, it likes the gas, but overall it runs aswesome, too much work to re do so i am leaving it alone.

Same here with the stock pipe opened up.


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