Jetting confusion, help mr. wizard


20 replies to this topic
  • boznblack

Posted December 05, 2008 - 06:33 PM

#1

My bike: 07 49 State 400E, stock FCR carb. Snorkel removed.
Elevation 2500 to 4500 typical range. Sometimes higher.
Carb set up:
145 Main jet (changed from 142)
DYP needle on 5th clip setting
Merge fuel mixture screw, 2 turns out
All else stock, including stock exhaust.
Bike is running very well, but want to get it to full potential

Needles needles needles. Don't want to spend on the JD kit. Which one is best if I am going to buy? EMM, EMN, EMP, DXP, or stick with stock DYP?

Honestly, going to larger main jet worth the mileage change? Was getting 49mpg with the stock 142 main.

Whats the real benefit of removing the coast enrichener? Which way works best...plugging all with vacuum plugs and changing to the 100 pilot air jet, or....leaving PAJ stock and connecting the two ports on the carburator with a short length hose. I've seen it both ways mentioned, and PAJs are not locally found. Worth the effort, or just a clean up?

Why does the MX version of the FCR need the PAJ removed and the stock 400E FCR does not?

BTW, the Merge Racing Fuel Screw was not a good fit. I had to remove the carb bowl and the plastic wing nut on the Merge, because the hole in the carb bowl was not large enough. Also, the Merge extended screw will not clear the starter motor unless you go to small 7mm nut on the end and toss the wing nut...

I've learned a ton from you guys, but it can get confusing for a novice tuner...

  • Eddie Sisneros

Posted December 05, 2008 - 07:11 PM

#2

is this a canadian bike? 07 drz E model in the us did not come with a fcr.there was no 49 state E in 07.

the stock needls is a DXP,not DYP.

the DXP needle works ok.the EMN is a better needle.

the bigger main jet is needed because of the snorkel removal.

main jet has little effect on gas mileage unless you are running with the throttle wide open always.

doesnt matter wich method of CE removal you do.works the same.removing the CE not only removes clutter the CE over time tends to become inconsistent.

the fcr-mx requires the PAJ to be removed becuase it has a internal passage difference.the fcr-mx is a completely different carb than the old style fcr.

the merge fuel screw is made for the fcr-mx.thats why its a little long.

you need to open the hole in the bowl regardless of fuel screw choice.thats no fault of merge.

  • Noble

Posted December 05, 2008 - 07:21 PM

#3

What Eddie said. Personally I like the original OBDXP needle. Use clip position 5 (from the top). I'm also happy with a 158 main jet. If you really do have a DYP needle, it is so close to a DXP its the same thing.

  • Eddie Sisneros

Posted December 05, 2008 - 07:26 PM

#4

i should have said the EMN is a better needle for agressive riding.

the DXP works well in a variety of conditions.

DXP works on clip 5,EMN on clip 3.

  • boznblack

Posted December 05, 2008 - 07:31 PM

#5

Thanks for the info Eddie! This bikes origins have perplexed me. I bought it new from a dealership in Florida in July 08. I was quite surprised to see it had the FCR when it shipped to my house (I live in Boise, Idaho). VIN indicates its an 07, but it has the FCR, thinner base gasket etc.... Maybe it has a different country code, but I don't know how to verify. Stock main jet is a 142, and it has the DYP needle.

With the EMN needle on 3rd clip, which main????

Thanks again.....

  • Noble

Posted December 05, 2008 - 07:48 PM

#6

Look on the steering head and front down tube for compliance labels. That may identify the counrty.

  • areyou4real

Posted December 05, 2008 - 10:57 PM

#7

FYI: The OBDXP needle may not always come stock. My 2006 US DRZ400E came stock with the OBDYP needle. At first, I thought it was mistake becuase everything I read on here, including the service manual said it should be an OBDXP.

Since the needles are identical except for the OBDYP being 1/2 a clip (0.45 mm) longer, maybe Suzuki changed to it in attempt to make the bike more emission friendly. Or maybe Keihin just changed it and didn't tell anybody :thumbsup:

FWIW, I am at 1000 - 2500' feet with the same setup as you - 3x3, stock exhaust. I am running a 155 main, EPN clip 4 (= EMN clip 3), 45 pilot with Keintech ext fuel screw at 1.25 turns out, and my bike runs great. My guess would be that this setup would work for you, too, if only you changed to 148 (most time at 4500') or 150 main (most time at 2500'); however, Eddie could confirm that for you.

  • Eddie Sisneros

Posted December 06, 2008 - 05:38 AM

#8

Thanks for the info Eddie! This bikes origins have perplexed me. I bought it new from a dealership in Florida in July 08. I was quite surprised to see it had the FCR when it shipped to my house (I live in Boise, Idaho). VIN indicates its an 07, but it has the FCR, thinner base gasket etc.... Maybe it has a different country code, but I don't know how to verify. Stock main jet is a 142, and it has the DYP needle.

With the EMN needle on 3rd clip, which main????

Thanks again.....


what pipe?

  • boznblack

Posted December 06, 2008 - 08:00 AM

#9

Stock pipe Eddie. Much thanks!

  • Noble

Posted December 06, 2008 - 09:39 AM

#10

4real - Cool. Didn't now that. As if "X" wasn't lean enough already.

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  • boznblack

Posted December 08, 2008 - 08:33 PM

#11

Hey areyou4real,

I put in a 150 main, and she runs great. I have the same problem you indicated on a post in October. My fuel screw doesn't affect idle until almost all the way in. (It came stock only 1/2 turn out). What did you do to solve this and the off idle hesitation you mentioned in an earlier thread. Mine seems to be rippin real good now.

  • areyou4real

Posted December 08, 2008 - 09:16 PM

#12

What are your current settings?

150 main
Needle and position?
Pilot?
Fuel screw? Did you optimize it? As long you're between 0.5-2.5 turns after optimizing, you don't need to change pilots.
Idle at 1800 RPM?
Did you ever check AP squirt duration? It should be 1.5s or less.

Optimize fuel screw as follows:
First, warm it up for 15 min or so.
With engine running, turn the fuel screw all the way in - lightly seat only!
Turn idle speed knob down until it just stalls.
Next, back out screw 1 turn and try to start it. It should barely idle.
Turn screw in slowly and note when it just stalls.
Back out screw to 1 turn and start it again.
Turn screw out and note when it just stalls again.
Set screw at the middle between the 2 stall setings.
Start it and then adjust the idle back up to 1800 RPM or so.

Also, it is normal to have a slight hesitiation when you blip the throttle in N, especially if you do it more than once because the AP starts to load up the intake with raw fuel. Check it when you ride it. How is it then? That's what counts.

Also, what's your idle speed set at? It should be set at 1800 RPM or so, which is faster than you might think. This will help as well.

  • boznblack

Posted December 09, 2008 - 05:28 PM

#13

Thanks ru4real, :thumbsup:

That is the best description on setting the idle fuel mixture screw I have seen! I'll give it a crack. I really appreciate your needle advice and know how. The Yamaha dealer was totally useless on the EPN needle. Ah well, I guess I'll have to go through Sudco or the TT store. Here are my current settings:


150 Main
Stock Pilot (assuming 45)
Merge racing extended fuel screw, currently 1.5 turns out.
DYP needle, 5th position.
All other jets stock, CE intact, stock exhaust, snorkel removed. 2500 - 4000 typical riding elevation.

  • areyou4real

Posted December 09, 2008 - 05:50 PM

#14

The Yamaha part number for the EPN needle is: 5NL-14916-PN-00

The dealer should be able to get it no problem. Since it's one clip longer, you'll need to run it at clip 4 instead of clip 3 like the EMN. Depending on your riding style the EPN may be of limited benefit.

You can also get it here, but the dealer is usually cheaper since you don't pay shipping: http://www.boats.net...4916-PN-00.html

  • boznblack

Posted December 09, 2008 - 06:47 PM

#15

Areyou4real, thanks again.

Just curious, but what are the indications that the fuel mixture setting is out of sorts while you are rding the bike?? Stock, the screw was out 1/2 turn. I ran it last weekend at 2 turns out with the new 150 main setup. I'm having trouble telling a difference while riding. Currently set at 1.5 turns out for my next riding test....

  • boznblack

Posted December 09, 2008 - 06:56 PM

#16

One more thing, any ideas on how to check rpms without a tach on my bike.

  • areyou4real

Posted December 09, 2008 - 07:39 PM

#17

No way to know exact RPMs unless you have a tach. If you have a bike with a tach you can compare them by ear, but there's plenty of room for error using that method.

From what I gather fuel screw tuning (and carb tuning for that matter) is part science & part art. If you do some research you will see that there are multiple ways to do it. I don't know which way is the "right" way, or even if there is a single right way. In the end what matters, is that your bike's pilot circuit responds and performs to your satisfaction. That being said, here are some good resources that I suggest you check out. I didn't know nearly as much about carbs until I started doing my homework.

http://www.dieseltwitch.com/YFZ450/

excerpt below from: http://www.factorypr...ch/carbkei.html

Fuel screw:

With the carbs synched, the engine warmed up to operating temperature, and the idle speed set, adjust the fuel screws so that when you rev the bike in neutral and release the throttle, the revs quickly drop to exactly idle speed again. If, when you release the throttle, the revs hang up a few hundred rpm above idle speed, then drop to idle, the idle mixture is probably a bit too lean. Turn the fuel screws out. Use a minimum of half turn increments until you know you've just about nailed it. You'll drive yourself up the wall trying to tune the thing in eighth or quarter turn increments if you're a mile off. In extremely lean cases the idle will hunt between the proper speed and something above it. If, when you release the throttle, the revs drop below idle speed then pick up, the idle mixture is probably a little bit too rich. Turn the fuel screws in. In extremely rich cases the engine will die after revving the bike and releasing the throttle, unless you've turned the idle speed screw way in, in which case it may act like the idle mixture is a little bit too lean. In slightly rich cases, the engine will respond well to throttle blips when cold, but will die or dip slightly below idle speed when hot.


  • boznblack

Posted December 11, 2008 - 05:18 PM

#18

Areyou4real,

You were right on the money with the EPN Yamaha needle. Dealer looked it up and its on its way with no shipping charges. Great call. I've seen it commented a couple of times now about the differences between the DXP and EMN (or DYP and EPN in my case). Both Eddie and yourself indicated that the EMN may only offer limted benefit, depending on your riding style. Can you clarify which type of riding style each needle type is better suited for? Thanks again for your sage advice.

  • areyou4real

Posted December 12, 2008 - 07:22 AM

#19

Both Eddie and yourself indicated that the EMN may only offer limted benefit, depending on your riding style. Can you clarify which type of riding style each needle type is better suited for? Thanks again for your sage advice.


EPN/EMN is better for aggressive riding.

The needle primarily affects 1/8 to 3/4 throttle. See here: http://www.keihin-us...mg/calchart.gif

Needles codes are composed of TAPER (1st letter), LENGTH TO TAPER START (L1) (2nd letter), and STRAIGHT DIAMETER (3rd letter).

How does each affect mixture? From: http://www.keihin-us.com/tune2.htm

TAPER: Changes are only made if there is a problem balancing the calibration between 1/4 and 3/4 throttle. If the mixture is rich at 1/4 throttle and lean at 3/4 throttle, a JET NEEDLE with a larger taper is needed. If mixture is lean at 1/4 throttle and rich at 3/4 throttle, change to smaller taper.

LENGTH TO TAPER START (L1): If the calibration is lean from 1/4 to 3/4 throttle, raise the JET NEEDLE by lowering clip position, or use JET NEEDLE with shorter length (L1). If the calibration is rich, lower the JET NEEDLE with a longer (L1) or by raising the clip position.

STRAIGHT DIAMETER: Changes the calibration in the transition range from the SLOW circuit to the MAIN circuit (1/8 to 1/4) throttle. A smaller diameter will make this range richer and a larger diameter will lean this range.

Knowing this, compare the DXP to EPN:

TAPER: D has less taper than E, thus D is richer than E at 1/4 throttle, but leaner at 3/4 throttle
LENGTH TO TAPER START (L1): X is longer than P, thus X is leaner than P at 1/4 to 3/4 throttle
STRAIGHT DIA: P is larger than N, thus P is leaner than N at 1/8 to 1/4 throttle

The following jetting calculator will allow you to really see what's going on: http://home.att.net/...ing_2002_VS.zip

Play around with it and you will get a good feel for how needles and jets affect mixture. It's a great tool to learn on and also has lots of good reference info.

  • boznblack

Posted December 12, 2008 - 04:13 PM

#20

Thanks areyou4real!

I kinda figured it was about aggressiveness. I'll mess around with em to get a feel.





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