James Dean Carb Kit Installed ~ I Need A Little Fine Tuning



95 replies to this topic
  • basicblues

Posted July 10, 2003 - 05:20 PM

#21

Lowedog,

Sounds like a stand up triple on your first at bat. Simple base hit clip adjustment and your home. Nice Job...

Despite being at similar elevations, with my 68 PAJ to your 100PAJ and my airbox possibly being modified heavier, I cannot get near your results.

Time to play the trump card. I installed the RED JD needle (4 position) late this afternoon. I already had a 165MJ installed and decided to start there. Right away I noticed my low end problems are gone and I have a little soft popping with an occasional backfire on decel. I adjusted the fuel screw and improved it somewhat but still backfiring. I changed to a 170MJ and adjusted the fuel screw back in a little. I am real close now and maybe there, I didn't get to ride much after making this latest adjustment. I still may need some tweakin but JD was right on in his earlier post recommendation. :)

I still have a issue of the bike missing when pushed to the peak in gears 1 thru 4. The bike pulls hard and strong up to that point. I may just be hitting the rev limiter because I am not use to reaching peak rev's this quick since switching to JD jetting.

Question: What's the major difference or response by going from a 68~70~72 PAJ to a 100 PAJ?

  • Indy_WR450

Posted July 10, 2003 - 06:45 PM

#22

tctrailrider, I am glad I am not the only one to notice the bike likes to be jetted spot on. I have also noted in other posts that needle length (type and clip position) and clip position 4 and 5 work best for stock needle lengths to give great response at 1/4 throttle. So I end up playing with needle diameter and tapers to get where I need to be. I am very satisfied with the EMN. I have not yet measured the JD needles to see where they fit on the Sudco chart. I have charted all my needles in main diameters, taper, and tip diameter. I am interested to see where JD needles measure. I will get to that this weekend. :)

  • Indy_WR450

Posted July 10, 2003 - 06:56 PM

#23

BasicBlues, I think the pilot air jet controls the air to the pilot jet for venturi type pick up of the fuel. Therefore a 100 PAJ should make the pilot circuit richer for the same pilot jet. I have heard mixed answers on this forum about leaning versus richer as a result of increasing the PAJ. There also seems to be a consensus on ratio of the PAJ/PJ size. You will find a chart on this forum that recommends a 100PAJ for a 45PJ. I am not able to comment on the logic since Yamaha Factory specs out a 100/50 for YZ450 and a 70/48 for the WR450. :)

  • Lowedog

Posted July 10, 2003 - 08:03 PM

#24

BasicBlues, I have found that the PAJ plays a major role in the pilot circuit. The bigger the PAJ the more air it lets through. For example, I jetted my carb to YZ standards as far as needle(NCVQ), MJ(162), and PJ(42). Then I noticed that the YZ runs a 100 paj compared to the 70 for the WR. So I installed a 100 PAJ and found it leaned out the pilot circuit too much. Quite a change actually because I was a tad on the rich side before. The reason the YZ can run this combo is because the YZ carb has no air cut valve (ACV). The ACV lets more air through naturally so that is why the WR has a smaller PAJ. So what I did was go to a 45 PJ and it was spot on with the 100PAJ wich I believe falls in line with Taffy's PJ\PAJ chart found in Jetting Qs.
So what Indy said is true that a bigger PAJ allows more fuel to flow but it takes the correct PJ to do so.

Anyway that is my understanding of how it works.

Lowedog

  • 450roost

Posted July 11, 2003 - 05:20 AM

#25

Just installed my JD kit.

170 MJ
red needle, 4 clip position
45 PJ (stock)
70 PAJ (stock)
FS 1-3/4 turns out
Temp 70
Humidity 84%
Elevation 1200 ft

**Was dark when I got done with the installation**

Would not start with E-start (Has been this way since yz cam) :D.Kick started on the 3rd kick with chock out.

Pushed chock in after 10 sec. and is seemed to idle ok. Since it was dark outside I did notice after about a minute the power bomb header pipe started to turn cherry red(scary).

I was able to ride around the yard and go through the lower gears at up to half throtle. Im not sure yet what to think.
It did not seem to have any misses when on the gas, it seemed to pop some when letting off. (ohh yea it really likes to backfire if you try to use the E-start).
My first impression was that it seems to either have less power over all or that maybe the power is just being more controlled. Feels like the bike is saying let me go, like it has the power to give but it's working hard to find it. It kind of felt more related to a XR 400 type power.

I would like to put some riding time on these settings this weekend since JD has said in the past that unless your bike is rally warmed up then it's not a true test. Is there any harm in this being that the pipe is getting so red? What should I watch out for as danger signs? I ride agressive woods and hill climbs.

My reason for starting out with the red needle was that most of the time the temps are above 80 degress when I get to ride. Could this be the reason I may be to lean? maybe I should change to the Richer blue needle. :D

I will follow up on Monday. Have a good weekend guys. :)

  • James_Dean

Posted July 11, 2003 - 06:40 AM

#26

Use the fuel screw to adjust the idle mixture, turning the fuel screw out will richen and reduce popping on deceleration.
Stock jetting will have the pipes glow red after dark too and the red marked needle is close to stock at idle-1/8 throttle, so look back at the jetting pre-kit to compare when setting up your bike. If you're jetting a bike for higher altitude and less oxygen (warmer temps), you can expect the jetting will be leaner when it's cool out.
The blue marked needle will run slightly richer at idle than red, and then evenly richen the lower half of the throttle range compared to the red marked needle. Even at full throttle there is a slight leaning effect from the red marked needle.

If you're riding in-between conditions, the red marked needle #5 or blue #3 are excellent alternatives.
-----------------

It's great to see the performance gains posted above!

Thanks,
James

  • 450roost

Posted July 11, 2003 - 09:16 AM

#27

JD,
When going for my test ride this weekend I will try turning the fuel screw out to adjust the idle mixture as you said. As I ajust I will continue to look for popping on deceliration and red pipe.
Sorry but I'm unclear as to what you was asking to look for when you sayed "look back at the jetting pre-kit to compare when setting up your bike". Was you meaning to compare what I was running before I used your kit? If so here is what it was
170 MJ
OBDUT, 5 clip position
50 PJ
70 PAJ
FS 3 1/2 turns out

At this time of the year I think most of my riding will be in-between conditions (HOT low elevation 80-95/mild 70's low elevation).
If the fuel screw out does not seem to fix then I will try the red marked needle #5 first. If I need try more the I will try blue marked needle #3.

I will stay with the 45PJ throught these test unless you (JD) think otherwise?

I'm ready for the weekend. :)

I'll update ASAP

  • James_Dean

Posted July 11, 2003 - 10:11 AM

#28

450roost,

You were using clip #5 before with DUT, so clip #5 on the red needle will be closer to what you had near idle speeds. The soft bottom-end power is because it's running leaner than before.
I'm a little surprised by the #50 pilot and 3 1/2 turns out on the fuel screw. Try turning the fuel screw out to 2-3 turns to see if the popping is reduced (with 45PJ & red #6).

The blue needle will richen the idle mixture and lower 1/4 throttle range, so if your bike likes the fuel screw out that far, the blue needle #3 or #4 is probably a better choice. This is the standard setting.

Thanks,
James

  • dominator426

Posted July 11, 2003 - 03:35 PM

#29

So what are these blue and red needles? Are they YZ optional needles? ELN or something similar??

  • Indy_WR450

Posted July 11, 2003 - 05:12 PM

#30

They are JD'S custom grind needles not available anywhere else. JD took the time to develop his own needles to make early 4 strokes run. He then went on to focus on KTM and is now supporting us with the WR series bikes. :)

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  • Ronnie Mac

Posted July 11, 2003 - 06:04 PM

#31

My wr450 sputters alittle.The sputtering follows the clip position on the needle. The lower on the clip on the needle the higher the rpm the sputtering takes place (hope this makes sence). Would I be a good canidate for one of JD's needles :D :) :D

  • James_Dean

Posted July 12, 2003 - 06:36 AM

#32

Dominator,

The needles are based on the ELP/EKP/EJP (YZ426 & 250 needles) and have richer and leaner diameters. There are 3 tapers to transition with more power in the 1/4 and 3/4 throttle ranges. The full throttle setting is also improved by using a main jet that matches the last taper on the needle.

It may sound like snake oil, but it's not. I've spent a long, long time getting these to the point where I felt they would be worth investing and having them machined for kits. The kits have instructions with settings, and the 2 custom needles with 4 main jets and spare clip.

Dirt bike manufacturers have stumbled around with jetting for years and it makes me and lots of other riders frustrated. A few basic settings and every bike should run great with nothing more than a main jet or needle clip change. These are simply at a more advanced level of development than stock single taper needle jetting. The bike manufacturers are spending all their time making new motors and saving a few ounces of weight. In a few years all the bikes will have something close to them.

Thanks,
James

www.JDJetting.com

  • captain_S

Posted July 12, 2003 - 01:11 PM

#33

Dominator,

The needles are based on the ELP/EKP/EJP (YZ426 & 250 needles) and have richer and leaner diameters. There are 3 tapers to transition with more power in the 1/4 and 3/4 throttle ranges. The full throttle setting is also improved by using a main jet that matches the last taper on the needle.

It may sound like snake oil, but it's not. I've spent a long, long time getting these to the point where I felt they would be worth investing and having them machined for kits. The kits have instructions with settings, and the 2 custom needles with 4 main jets and spare clip.

Dirt bike manufacturers have stumbled around with jetting for years and it makes me and lots of other riders frustrated. A few basic settings and every bike should run great with nothing more than a main jet or needle clip change. These are simply at a more advanced level of development than stock single taper needle jetting. The bike manufacturers are spending all their time making new motors and saving a few ounces of weight. In a few years all the bikes will have something close to them.
Yep for sure i just know james is right!,colour coding is a way to identify the one you need,sure i have a bike that runs well 2 depending on how i ride,if i go looking for a fault i can always find one,but no kit will help if you go out and just "thrash it `n` bash it",i think if standard parts are ok for you the jd kit wont help,but if standard parts dont give you just what you need james jetting kit may just give the bike that extra kick!.I think james dean has shown a lot of courage and bottle to put his neck on the line here,i reckon he knows the score and fair play to him too,a tripple needle taper has got to be a first,a pioneer even!,good on ya man. :)
Thanks,
James

www.JDJetting.com



  • Indy_WR450

Posted July 12, 2003 - 02:58 PM

#34

JD Blue rocks! :D :D
I thought I had the best needles going with the EMM,EMN,EMP. Then this weekend I measured the JD blue needle diameter and taper and found it to be richer down at 1/4 throttle and leaner at 3/4 throttle. So using my experience with this beast I put the JD Blue in clip #5 and upped the main jet to a 165. The bike is better then I have had it run in the summer. I thought I was on the right track with the other needles and smaller main but this combination works very well. My bottom end stayed the same but my midrange and top end felt stronger. JD did his home work well. This blue needle fits me very well. Today it was low humidity and 72 degrees. Perfect riding weather with near perfect jetting. What a blast! :)

  • Mike_Hudson

Posted July 13, 2003 - 04:47 PM

#35

Thanks to JD and TT :D As a 4 stroke rookie I could never have brought my bike to where it is now. Here is what I had:
OBDUT 4 clip pos
MJ 160
PJ 48
Stock MAJ (200) & PAJ (70?)
Running about 3/4 out on fuel screw (original set up was done back in Feb when it was 60 deg F)
See below for mods

Got my JD kit, current temp 90 deg F with 80%RH. Based on other posts and the instructions that came with JD's kit, I went with the following

"Red" needle, 4 clip pos
MJ 170
back to PJ 45
Fuel screw 1 3/4
FYI-I run 100 octane unleaded racing fuel

Ran a 10-mile loop (tight single track ran 2nd gear from idle to limiter occasionaly touched 3rd), main was obviously too rich with sputtering at top end as revs built. Changed to the 168 main....very good overall. Sputtering on top gone. Only question left is the pilot circuit. I tried the trick for setting the fuel screw by running idle up and listening for pickup in speed...I am clearly not very good at this as the bike would still run if the screw was completely in or 3 turns out :D I ran at 2 1/4 for most of the day. The snap open the throttle in neutral will bog the engine although this doesn't seem to hurt anything on the trail. (Is this snap throttle thing a real test?) With this pilot setup or the old setup I have never experienced any decel popping. Should I go down to a 42 PJ and listen for the pop and slightly richen?

Performance is just awesome. I kept the bike in 2nd almost all day..my only problem is keeping the front wheel on the ground! :)

Mike

  • James_Dean

Posted July 13, 2003 - 07:38 PM

#36

Great to see the results here!

-The "Air Bypass Valve" ( or Air Cut Valve) will reduce or eliminate popping on deceleration on the WR, so no need to go looking for it.
-Performance while you ride is the best way to judge the idle mixture. If it feels crisp and has good torque from the bottom, keep the settings and go have fun.

Thanks,
James

  • 450roost

Posted July 14, 2003 - 07:29 AM

#37

JD:
Just wanted to following up with what I tryed this weekend. Turning the fuel screw out to 2-3 turns to see if the popping was reduced (with 45PJ & red #4)I't continued to get better (no popping) but the soft bottom-end power was still there from running to lean.
Saturday I decided to try the blue needle it was better (night and day), the bottom end is really snappy and there is no popping or hesitation throughout the throttle range.
I would have started with the standard settings but I figured that the temps here would be more toward using the red needle (wrong :D).

End Results:
170 MJ
blue needle #4 clip
45 PJ
70 PAJ
FS 1 3/4 turns out
Temp 74
Humidity 81%
Elevation 1200 ft

Thank you JD for all the great advice. I'm happy with the results. :)

I may later try the #3 position on the blue clip. Would like to see if I can get just a little more from the top end.

Thanks, Rick
:D

  • Mike_Hudson

Posted July 14, 2003 - 11:12 AM

#38

Are most of you guys leaving your pilot setup the same as pre-JD needles and just changing MJs? I changed my PJ from 48 down to 45, but am wondering if the 48 and less turns would be better? I'll probably swap it out and see this weekend. Just to help my understanding is the performance equal if you have say a 45 w/several turns (dialed in appropriately) vs. a 48 that is close to one turn?

Thanks for the expert opinions.
Mike

  • Indy_WR450

Posted July 14, 2003 - 01:41 PM

#39

Mike,
I like staying with the 48 pilot and adjusting the screw close to 1 turn. There is a difference. The 48 pilot gives me more bottom end snap. I run the JD Blue needle because my low end pipe needs it. Stock pipe should work better with the red needle. I am not a fan of changing the pilot on the WR450's the carburator is very different from previous years and the pilot circuit should be adjustable with the air screw. I set my bike to idle and run at 6 mph (Panoram & stock gearing ratio in first gear) with no throttle. If it stalls then I adjust the air screw in until it does not. That is where it rips from the bottom and runs the best. Forget this high idle low idle because my bike runs with the zip ty screw all the way in without stalling. I have tried the leaner pilots from 45, 42 , 40 and 100 PAJ combinations and JD is right to say this bike does not need its pilot circuit messed with unless you can not get it to idle with the air screw. :)

  • Beta_Man

Posted July 15, 2003 - 05:03 PM

#40

The kit is designed to work with the stock US jetting on the wr 450 will it also work with the canadian jetting too. I know all the jets are diffrent, but i am not sure what the stock canadian paj, sj and maj are I know the pj is 48 and mj is 160 also the needle is diffrent. the elevation i ride at is from 3500' to 6000' some times 8000' with temps around 70 to 85 in the summer.




 
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