Another leak jet question


6 replies to this topic
  • projected

Posted January 23, 2010 - 05:35 PM

#1

I've searched and read and still have a question.

I just bought a <10 hour like new 07 WR450. I only rode the bike once in my neighborhood and could tell the jetting was all wrong for 6000 feet and 45 degrees. The bike was supposedly jetted for sea level (still had stock needle) since it came from CA.

Anyway I've got the bike apart to grease the linkage, swingarm and head bearings. I also bought the GYTR AIS removal kit as well as an 07 YZ std needle and have taken all the garbage off.

Since this carb is so difficult to get to should I just put a #40 leak jet in now while it's all apart or just leave it stock and find out later if I have a bog? I haven't read anything negative about using a #40.

I would think know one can know 100% for sure what I should do, I'm just looking for opinions whether I should start with the stock leak jet or with the #40. Any advice would be appreciated, thanks.

  • jlow

Posted January 24, 2010 - 06:12 AM

#2

projected, go to the sticky seciton for the wr's. bottom sticky, think it is the performance index. click on the jetting database. bout 3 or 4 posts down, you will see a post by indywr450 with all the specs you will need for jetting. you will need a james dean jet kit and adjustable fuel srew. some people say the jd ket kit is a waste of money, but i disagree. my ais kit came with a 175 main, way to rich. rode with the ais kit setup for awhile, but after doing the setup per indywr450, way better perfromance!

  • William1

Posted January 24, 2010 - 10:15 AM

#3

Stick the #40 leak jet in.
Do the oring on the AP linkage or install a Merge Racing AP spring.
Jet according to the excellent instructions that come in the James Dean jet kit.
Ride the bike and adjust the AP timing screw until the bog (if it has one) just barely goes away.

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  • projected

Posted January 24, 2010 - 10:33 AM

#4

Stick the #40 leak jet in.
Do the oring on the AP linkage or install a Merge Racing AP spring.
Jet according to the excellent instructions that come in the James Dean jet kit.
Ride the bike and adjust the AP timing screw until the bog (if it has one) just barely goes away.


Thanks William. I don't know if I have a bog since I haven't ridden the bike yet. I'm just looking for the best baseline for the leak jet since I have the bike apart already.

In your opinion I should put it back together with the #40 correct?

What I would like to know is: Is there a negative to using the #40 if you don't require it? Is there any reason not to put the #40 in?

Thanks.

  • William1

Posted January 24, 2010 - 02:18 PM

#5

Ride the bike before you do anything. You have to have a baseline to know if what you are doing is better or worse.

With a #40 and a properly adjusted AP timing, you will never have a bog. The down side is fuel consumption can go way up.

What you want to do is run the largest leak jet you can, with the AP timing set just right and not have a bog during 99% (almost any 4S can be forced to bog, that is the 1%) of normal riding.

Out of the box leak jet selection is based on how good a rider you are and the type of riding you do. If you are an A class desert racer, the stock leak jet is fine. Possibly true for the same rider on an real MX course. Get into a stadium or other slower venue and a smaller leak jet may be needed. Same goes with rider ability. I run a #55 (I use an adjustable leak jet) most of the time and I mostly ride tight woods.

  • projected

Posted January 24, 2010 - 04:44 PM

#6

William stop making sense, I was trying to be lazy since the bike is apart but I guess I'll have to do this the correct way. :banghead:

I like very technical mountain singletrack as well as desert singletrack, I ride at an A level.

Thanks again.

  • OUTERLIMITS

Posted January 25, 2010 - 02:37 PM

#7

Probably best to look at the database for what others have done at your elevation. I'm in So Cal so cannot help, but will say that the 40 leak was a big help to me as it got rid of that last bit of hesitation right off idle (no AP timing adjustment needed for mine). I would rather see what others have run and go from there to do it once, but at worst you'd only have to pull the bowl off and not the whole carb anyway.




 
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