Michigan Jetting questions with mods.

OK, first post, new bike. I purchased my bike over the winter and only rode it twice stock. Just installed the duall sport kit and BD Baffle. I have been reading much on the forum and wanted to see if anyone in Michigan (or Midwest) has any advise on the stock Jetting. It seems to be fine stock but everyone seems to want to change the stock jetting? My airbox cover is removed which would suggest a leaner mixture. I am used to riding Honda's and they never seem to have jetting problems (XR models). Just trying to figure out optimum settings. Is the Jetting really that finicky on the WR? :)


You need to either get the YZF throttle stop or cut yours down. Also look into the BK mod. I think if you raise the needle one clip you will be very happy. My setup is in my signature, stock jetting, needle raised one clip and in a little on the fuel screw. Starts great and runs wonderful. With a Vortip you won't need to do much with the stock jetting to get it rippin. Also check out this site, its for the 250F but the info. is the same.


It seems to be fine stock but everyone seems to want to change the stock jetting?

The stock WR jetting is kind of weird IMO, and that is why a lot of folks want to improve upon it. The stock restrictions (lid and baffle) are pretty extreme, so it stands to reason that the stock jetting would have to allow for this. So a lot of jetting changes get made during the process of getting the motor to live up to its potential (uncork/unstop/uncover).

Another way to look at this is you are turning your WR motor into a YZ version. So why not use YZ jetting? I've jetted three WR's to identical settings as my YZ and of course they then ran pretty much like my YZ (one had YZ timing, stock uncorked, other two had WR timing and WB exhaust).

A lot of guys at lower elevations like the ELN needle, an option from the YZ 250 fiche that is a bit richer than the stock YZ 426 needle.

Hope this helps.

I will try the clip position thing. I looked into the BK Mod..a little intimidating as I don't like messing with Carbs. Maybe I will get around to that a little later. How long did it take to perform? Is there an easier way to do this without taking the subframe off?

I've done all the free mods to my bike which is an '01 and the work is easy. The bike ran rich after doing the airbox and exhaust and fouled plugs. I then went to the settings in my signature (with a few adjustments to get me where I am today.) I may go leaner as the temps and humidity both are above 90 as the typical MI summers go, but I am really happy for now. It ran great this Friday and Saturday at Mio and Bull Gap in 45-55 deg F.

The BK mod is simple and makes a lot of difference and none of the free mods requires the removal of the subframe, just the seat, shrouds and tank. The carb should not be looked at like something difficult to tackle, its really easy to adjust once you do it the first time. The total time on all the mods, if done all at the same time should not be more than 2 hours even for the newbie. I've found that it takes me longer to drain the carb and remove all the other stuff than to remove the carb itself and adjust. I would recommend the following mods: get a Kouba t-handle to make adjusting the fuel screw easy, remove the grey wire, install the YZ throttle stop (or cut the WR one), remove the light blue wire, which makes starting easier and so far has reduced the # of fouled plugs since removal.

If you haven't yet done so check out www.cycleconservationclub.org for a great group of trail riders. The Rites of Spring are coming up May 3-4, can't wait.


My earlier post to you I was running stock jetting on clip 5 with very good results. Past weekend the temp. got up to 70 and I developed a miss at about 1/3 throttle. Went to clip 6 got worse, clip 4 (stock) pretty good. Had an EKN needle and put it in on clip 3 with a 160 main jet. Great results. I need more ride time with it but so far I like it.

P.S. Did you cut that throttle stop yet?

Thanks again. I have checked out the CCC over the winter and I am considering joining. Might not get to ride a whole lot as I am expecting my first baby :) I did do the throttle stop over the weekend. I may try the ELN or EKN needle as the weather begins to warm up. I am assuming that when I pull the carb to do the needle, I will attempt the BK. I have read a few other posts in similar climates that left the main at 165. I may leave that alone at first to see how it does.

Hey Holland,

I am just north of you in Muskegon. If you need someone to ride with just give me a shout. I am always up for a ride either saturday or sunday morning (wife works nights).

I am a ccc member also. As well as a local chapter of the ccc called the West Michigan Trail Ridders.

My yz is scattered all over my buds garage right now. Maybe in a week or 2 it will be runnin again.

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