JD jet kit any good

[Rider1998]

Wondering if this kit is worth it

[Tankslap]

I bought it for my YZ125 (a few years ago, and have transferred it from the original bike to my current one), but not my YZ250.  Really, you are just paying a ton for the needle, unless you don't have the main jet(s) you need either (which are fairly cheap).

I think most guys here will tell you it is unnecessary for the YZ250.  Lots of guys recommend the Suzuki needle, while some recommend the #8 slide instead (I'm in the latter group).  Everybody recommends sending off your head to correct the squish no matter what else you do, and preferably before you even mess with the jetting.  So if it were me, I'd say no it's not worth it...that money is much better put to use fixing the head.

[Rider1998]

What Suzuki needle and why is it recommended so much

[rpt50]

The JD kit is awesome if you live in a city or somewhere where you can't conveniently do a lot a testing before a race or ride.  I've used them for several bikes and they typically need very little tinkering before they are ready to go.  Also great for the summer when it's to damn hot to spend time swapping brass. 

[Tankslap]

4 hours ago, Rider1998 said:

What Suzuki needle and why is it recommended so much

NECJ (or NEDJ to go 1/2 clip position leaner).  Just do a search on this forum for "NECJ" and you'll find a lot of posts.  The rationale is, the stock needle (and its close siblings) are a bit fat at 1/8-1/4 throttle and then a bit lean after that, causing a sputter-then-hit transition through that throttle range.  The problem being that you can't fix one issue without making the other worse.  I personally did the squish and slide first (I live in Colorado, and the leaner slide works well here), and used the needle that is half a clip leaner than stock, and I never really had an issue in that throttle range at that point.  My YZ250 is a track bike though, and maybe if you ride ST/woods more it could be more noticeable if you are constantly traversing that range.

If you do decide to use the NECJ, I believe you have to run a leaner main jet than you normally would (by 2 sizes or so) because that needle is richer in its upper range that overlaps with the main.

[Rider1998]

I think I got it now. The bike came with the N3ew needle and It has always been too rich. So I had a the stock needle laying around which is the n3ej put it back in and wow what a difference that's as close to a brown spark plug I have ever got too so I think that was my problem