Anybody run the Dubach jetting from the Feb Dirt Bike mag?


10 replies to this topic
  • cbrandt

Posted February 04, 2008 - 02:25 PM

#1

I am wondering if anybody on here with a 2007 or 2008 has tried the jetting that Doug Dubach came up with in the Feb issue of Dirt Bike. He was de-restricting the bike and used a widband Oxygen sensor to datalog the A/F ratio. He came up with theese settings:

The February Dirtbike actually had an interesting article in it.

They had Dr. D hisself doing a de-smog on an 08 WR450.

It was the usual binocular removal, YZ throttle stop, grey wire cut and a Dr. D pipe with a quiet insert.

He used data acquistion techology with a lambda exhaust sensor to do the jetting none of which I have a clue about.

His results were a 162 main, a NCVQ#4 needle and a 48 pilot. The stock leak jet was used and he had to adjust the accelerator pump was adjust 1/2 turn in from stock.

I am hoping somebody has run this set up with a stock exhaust (no baffle) and can report on the jetting at or near sea level.

Thanks guys

  • JSanfilippo

Posted February 04, 2008 - 03:03 PM

#2

His results were a 162 main, a NCVQ#4 needle and a 48 pilot. The stock leak jet was used and he had to adjust the accelerator pump was adjust 1/2 turn in from stock.


Jeez thats kinda lean for running a race pipe:excuseme: I mean the 162 main is stock and barely enough for a choked up WR...unless the NCVQ needle is hella rich.:busted:

Here is my jetting
165 main, JD red #4, 48 pj, gray wire, MSR F/S @ 1.75 turns (winter, 1.25 summer), o-ring mod.

Opened airbox, twin air filter, and stock muffler w/ PMB insert

Ridden with this set up from 1000ft-5000 ft and from 38 degrees F to 100 degrees F and it runs pretty good. Runs best around 2500ft at about 65 degrees. Even at 38 F it ran good with smooth, crisp, instant throttle response.

  • 123BigcoopDawg576

Posted February 04, 2008 - 03:39 PM

#3

Jsan is correct...also it should be stated that what works for DR. D doesnt mean it will work every where else as temp and elevation will be different.

  • erickdj

Posted February 04, 2008 - 04:05 PM

#4

Jeez thats kinda lean for running a race pipe:excuseme: I mean the 162 main is stock and barely enough for a choked up WR...unless the NCVQ needle is hella rich.:busted:

Here is my jetting
165 main, JD red #4, 48 pj, gray wire, MSR F/S @ 1.75 turns (winter, 1.25 summer), o-ring mod.

Opened airbox, twin air filter, and stock muffler w/ PMB insert

Ridden with this set up from 1000ft-5000 ft and from 38 degrees F to 100 degrees F and it runs pretty good. Runs best around 2500ft at about 65 degrees. Even at 38 F it ran good with smooth, crisp, instant throttle response.


I'll agree with Joe on this one. I've run a race pipe on the WR and a 162 mj would not be nearly enough. That's just too lean on the main. On the other hand, he might be on to something about the taper of the needle, it could be a pretty rich setup.

  • cbrandt

Posted February 04, 2008 - 05:13 PM

#5

Thanks guys,

The reason I asked is because it sounded so different from what everyone else is running. On my bike, I have run between a 168 and 175 main with best results from the 170 at about 50 degrees and virtually sea level. I have run the stock emissions needle and now the AIS kit needle and I have been up and down on the clip setting to find the best rideability at all throttle positions.

I feel like there is room to improve my bikes manners in the 1/8 to 1/2 throttle range because it still has a pronounced lean surge in these conditions at light load and steady throttle. I have adjusted the TPS and even tried riding the bike with the TPS unplugged but the symptoms are only reduced - but clearly not eliminated. So, I feel like it is a needle issue and want to get it sorted out....mostly because the bike is plated for dual sport use and light load steady throttle conditions come up a lot more on the street than on the dirt:banghead:

I have spent enough time trying to feel out the jetting so I am ordering a titanium nut to weld into the head pipe so I can run my own wideband oxygen sensor and datalog some results. I'm not sure that I will be able to rig the system up for a full test ride with the datalogger in place but at least it should nail down the pilot / needle transition at light load

Later,
Chris

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  • suzukipoo

Posted February 05, 2008 - 12:14 AM

#6

My bike 07 wr450 also had a surge in the same spot so i dropped the ais needle 1 place to make it leaner 3 rd clip from top and whola it runs perfect with the 170 main, 48 pilot, 1 1/4 turn fuel screw twin air filter, fmf factory 4.1 slip on, all free mods!!!!

  • JSanfilippo

Posted February 07, 2008 - 12:51 AM

#7

I feel like there is room to improve my bikes manners in the 1/8 to 1/2 throttle range because it still has a pronounced lean surge in these conditions at light load and steady throttle. I have adjusted the TPS and even tried riding the bike with the TPS unplugged but the symptoms are only reduced - but clearly not eliminated. So, I feel like it is a needle issue and want to get it sorted out....mostly because the bike is plated for dual sport use and light load steady throttle conditions come up a lot more on the street than on the dirt:banghead:


I've read of this TPS issue in the past...funny thing is I've never had a lick of trouble with it :busted:

I should unplug it and see what happens just for shits and giggles:ride:

  • beezer

Posted February 07, 2008 - 06:26 AM

#8

I think Dr. D was running the pipe with the quiet baffle in place so that might make a difference.

He was using some pretty sophisticated equipment so it wouldn't be a bad idea to give give his jetting a try.

  • JimL

Posted February 26, 2008 - 04:54 AM

#9

without knowing the relationship between main jet size and needle size it's hard to know if he's leaner or richer than what we're running. anyone know how the ncvq needle compares to the jd red needle, the ais needle, and the yz needle. Doug Dubach is certainly the man when it comes to yamaha's, and that is some high tech equipment he is using for dirt bikes. My bike runs good but it's always in the back of my mind could it run better? I hated the fact that I had to spend money on an ais kit and then turn around and buy a jd jet to get my bike to run right.

  • Idaho450

Posted April 16, 2008 - 08:24 PM

#10

That's pretty close to the jetting I run, except with a 45 pilot. How's your mileage? Mine was terrible with a 50 pilot ( an accidental holdover from the ais kit)

  • tweav

Posted April 16, 2008 - 09:30 PM

#11

what I find really odd is my jetting was done on a dyno . and look at everbody else's mine is way lean . does the dyno lie? or does everybody believe more fuel is aways better ? I don't really get it I'm running a full fmf pipe all the free mods , a zip ty fuel screw , a rd power bowl 1/2 turn out a dyno jet jet kit , needle clip on the 3rd one from the top , a 42 pilot jet and a 150 main . at 75 degrees at 750 ft above sea level .

I really think people should just put it on the dyno instead of guessing . but hey to each his own right ?




 
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