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Well, DR.D full system, race setup.
450x 06 model
twin air filter
the little 1" round air box vents

Want a good bottom and mid range punch, any suggestions on how many vents, what jets, and fuel screw/other settings to get this thing setup?

I'm at about 1000-1600 elevation.

Thanks in advance for the input!

are you running stock jetting now? if so, get the jd jetting kit for jetting. as far as opening up the air box start with the air filter and cage. the backfire screen is very restrictive. you can either remove it or replace the cage with the twin air powerflow kit. the kit includes a free flowing air filter. if you go the route of just removing the screen then get the twin air powerflow replacement filter to replace the stock filter. with the JD kit and this level of air box/filter modification you'll notice great improvements. if you feel you need more than read the how-to on modifying the air box for increase air flow.

ken

crfsonly wrote:are you running stock jetting now? if so, get the jd jetting kit for jetting. as far as opening up the air box start with the air filter and cage. the backfire screen is very restrictive. you can either remove it or replace the cage with the twin air powerflow kit. the kit includes a free flowing air filter. if you go the route of just removing the screen then get the twin air powerflow replacement filter to replace the stock filter. with the JD kit and this level of air box/filter modification you'll notice great improvements. if you feel you need more than read the how-to on modifying the air box for increase air flow.

ken

Yea, I'm still at stock jetting, I've not installed anything yet (meaning pipe, filter, so on so forth) the bike is still fully stock. I just have all this stuff ready to install. I do have the twin air powerflow filter, instead of the cage I'd probably rather remove the screen, I think it would work about the same. Will the JD kit cover it all the way up to the air box mods? I suppose the correct question would be, does it have a main jet large enough to cover that? Thanks!

jlee_evans wrote:

crfsonly wrote:are you running stock jetting now? if so, get the jd jetting kit for jetting. as far as opening up the air box start with the air filter and cage. the backfire screen is very restrictive. you can either remove it or replace the cage with the twin air powerflow kit. the kit includes a free flowing air filter. if you go the route of just removing the screen then get the twin air powerflow replacement filter to replace the stock filter. with the JD kit and this level of air box/filter modification you'll notice great improvements. if you feel you need more than read the how-to on modifying the air box for increase air flow.

ken

Yea, I'm still at stock jetting, I've not installed anything yet (meaning pipe, filter, so on so forth) the bike is still fully stock. I just have all this stuff ready to install. I do have the twin air powerflow filter, instead of the cage I'd probably rather remove the screen, I think it would work about the same. Will the JD kit cover it all the way up to the air box mods? I suppose the correct question would be, does it have a main jet large enough to cover that? Thanks!

Yes.

The jd kit I purchased had 1 pager of instructions that just said in order for this mod to work the airbox must be cut. The instructions showed how to cut your air box.

It then advised you on what jets and needle to use given a cut airbox. It did not go into baffle removed or or not removed, or anything about the air filter and screen. It did give good details about altitude.

I removed the baffle and it is running great.

I did email JD Jetting asking if I remove the screen would that require a different jet than what the instructions indicate. Someone told be me removing the screen would increase airflow by 20% and requiring rejetting. Let's see what JD jetting says.

Seriously bud,
You are worrying ...and thinking...way too much.
The JD kit works great at the suggested settings whether your baffle is in, out , or modified, same with your air filter screen.

Someone told be me removing the screen would increase airflow by 20%

Not in a million years.
Incidentally, my X had a HotCam Stage 2, a full aftermarket exhaust,a TwinAir screenless filter cage, the JD kit, and 162/45, and 1.75 out on the fuel screw had it running razor sharp with a beautiful tan plug. Some guys run 165's,some 170's, but most all stay put with needle clip position.
Ride your bike. After a couple hours pull your plug and check it. Note what rpm you spent most of the time at.
A lot depends on your type of riding, elevation but only in extremes as in very high matters, and temperature.
Most all eventualities with an open airbox,a JD kit or NCVS set-up can be dealt with by a tweak in or out of the fuel screw. You will find that most of the time what you need to do with your bike set up either way is....nothing.
Ride your bike. Get a plug read.Stop sweating the small stuff. Doug

I went 170 main, 42 pilot, and ncvs needle for now... all my wife would let me afford

I think it'll be fine, JD kit maybe in the future since I hear really good things about it, but in all honesty, my bike is hardly even broke in (about 200 miles at most). Which reminds me, I need to check up on a couple things in another topic.

Well just to close the loop...according to JD jetting....

Question: I have 05 250x with cut airbox, stock filter, and baffle out. I am moving to a Twin Air filter and thinking about taking the screen out. Would that require rejetting?

Answer:

Yes, please increase the main jet by 2-3 steps with the screen removed and TwinAir filter. The filter alone will allow 1-2 steps bigger main jet.

But your point is well taken. Just ride the thing and check the damn plug.