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DRZ400 jetting question


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Hi Eddie,

I did the 3 x 3 mod with JD kit installation and extended fuel screw ( I have KN filter in and stock exhaust; mostly ride at 800ft). I basically followed JD's intsructions, which is:

- blue needle, clip at the 3rd

- mj 155

- pilot 25

- fuel screw 2.5

Bike idles great, snappy at the bottom end. The only questionable for me is the last 1/3rd of the throttle pull. It seems like it didn't get better (compared to stock jetting ..), I might even loose some top speed (I did few passes on the hwy, which is hardly conclusive, but that's the way it feels for now ...). It feels like it stops building speed a touch earlier than it used to, especially in 5th gear.

I noticed that 3 x 3 post recommends clip at 2nd. I also noticed that you said that 22.5 pilot should be used when extended fuel screw is used. Considering that the bottom end and idling is fine, should I go back to 22.5 or leave it as is?

Thanks for your help,

Marek

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take the air box door on and go ride.if it pulls harder at high rpm you need a msller main jet.if its worse,tape off 1/3 of the hole and put the door back on.go ride. if its better you need a bigger main jet.

also typically 4th clip works better.

22.5 is usually needed with the extended screw to have control over the pilot circuit.

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Thanks Eddie. I will do the testing with the air box door and see what my bike will like better.

Could you pls explain to me what exactly does the position of the clip do and why is 4th generally better? Is it the part of taper on the needle in relation to the throttle position?

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I ran some tests yesterday as you recommended. I have a feeling (and I hope I am not getting fooled by the throaty sound of the air box honk/thump sound when ran without air box door; it's very easy to do ...), that I am running rich so I am planning to put 150 main in and see how it goes.

Now considering the clip position ... if I go to 4th as you suggested, how big of a change is it when compared to the drop from 155 to 150? I can easily experiment with the clip position without getting the carb out, but I just don't trust my testing skills as much. I am just trying to get a feel for changing a clip position vs main jet. I realize that the clip position only affect partial throttle, not WOT.

Thanks

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