stock (OBDUQ) needle with air box cut outs


9 replies to this topic
  • simon@vic

Posted March 23, 2004 - 06:28 PM

#1

i have cut out the indents in my 04 air box and i cant seem to get the mid range perfect. 90% of riding time it is fine, well actually amazing when grunting in tight single track or when wailing down a fire road banging through the gears.

the problem if you wish, occurs when i get fallowing a car in traffic at a steady speed. it seems to flutter a bit when you have to hold it at 1/8th-1/4 for an extended period of time.

I'm at sea level and jetted as fallows.
165 main
48 pilot
80 PAJ
OBDUQ-4 {i tried 5 and it was a bit worse}
1 3/4 turns
airbox ovals cut out
end cap out

i guess my question is can i use my stock needle and not have this problem? thx for any input.

and I'm loving the power :moon:to the 400 :worthy:to the 450

  • simon@vic

Posted March 25, 2004 - 05:47 AM

#2

any one?

  • ckulzer

Posted March 25, 2004 - 08:57 AM

#3

Simon,
The 04 WR450 comes with a DWR needle in the US and my 03 came with a DUT. If you have a DUQ, it means that you are about 10% richer up to 1/8th throttle compared to my DUT with all other settings remaining constant.

With the clip on position 4, I would try a DUR or a DUS needle since your problem got worse when you went to clip position 5. One step on the clip is a big jump compared to a needle with slightly less diameter.

I hope this helps.

Ride fast - take chances

Chad

  • Taffy

Posted March 25, 2004 - 02:58 PM

#4

can i butt in on this post and ask whop has a yamaha part # for that OBDUQ needle please?

cheers

Taffy

  • simon@vic

Posted March 25, 2004 - 06:05 PM

#5

part # for that OBDUQ needle please?



5TJ-14916-D1

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  • simon@vic

Posted March 25, 2004 - 06:13 PM

#6

If you have a DUQ, it means that you are about 10% richer up to 1/8th throttle compared to my DUT with all other settings remaining constant.

With the clip on position 4, I would try a DUR or a DUS needle since your problem got worse when you went to clip position 5. One step on the clip is a big jump compared to a needle with slightly less diameter.
I hope this helps.


it does help thx. what you are saying it to go leaner then stock for the low-mid to mid range? why? i have way more air and exhaust flow then stock. maby need a bit more but not as much as jacking the needle up.

I'm going to try a bunch of things. and keep the ideas coming.

thx

  • Taffy

Posted March 26, 2004 - 01:17 AM

#7

simon

i'm only here for the needle code so thanks for that but the information isn't quite right that you have been given so let me explain.

as long as JD has told the truth to me, the new Q needle's taper is set between the D and the E series needle tapers.

put simply, i want you to imagine a pivot point in the middle of the needle taper. it's exactly 2.515mm wide ok. the D series has a shallow taper and a fat point whilst the E series have a sharp taper to a sharp point.

this means that-using this pivot point-the taper of the D series needle doesn't hit the side wall or the 'straight bit' of the needle until a lot nearer the clip grooves.

so up to the 2.515mm point (that means from where the taper starts to this measurement) the D series is thinner and therefore allows MORE fuel past. from this 2.515mm point the D series as we've said barely tapers in and the E series sharply tapers in to that sharp point.

so the D series is richer at low revs, ok? the Q series sits between the two so that it's a compromise.

JD's needles are an E series with a D series grind up from the side 'straights' to somewhere around the 2.515mm mark.

i can't emphasis enough that to understand this all anyone has to do is draw a needle. forget all dimensions. then draw another one over the top with a different coloured pen only this time make the point a lot higher up and draw through the side of your first taper to the sidewalls so there is a cross point, (same both sides) you'll note that your original needle has longer straight sides before 'starting' it's taper.

so A q series is leaner than a D series at low throttle and not richer. that last suffix is the width of the needle straight and nothing else. it's dead easy to work out. an A is thin and therefore rich and a Z is thick/wide/fat and is therefore lean.

the width only affects tickover (idle to you 'guys'!) and just as you move off in first gear for ooohhh? maybe 1 yard and at the most two yards. that is all the width does.

so don't change the needle straight for anything else.

if you have a low speed hesitancy it is 90% of the time the needle is too high/rich and needs dropping two clips. that's two :)

your pilot jet is very very rich and added to this it's not in ratio to your PAJ.

the ratio, which you'll find on 'jetting Qs' as well. is; 15 0f air to each PJ.

so 35PJ is 45 PAJ and 38PJ is 60 PAJ. i suggest that you come down to a 40PJ maximum, drop the needle two and PM me as i don't visit here too often now although i'll keep an eye on this thread to help sort you out if i can.

good luck with it.

PS was the DUQ the only Q series i can get at the moment?

Taffy

  • simon@vic

Posted March 26, 2004 - 05:30 AM

#8

DUQ
came in my bike.

your saying to try it on pos #3.leaning it out when everything else {except main} is jetted stock??? and i have more airflow and exhaust then stock? i will try.........but...........

I'm am waiting on the 04 yami tech update book {coming soon} to see what there "closed course racing mod" suggestions are.

and thx for the info.

  • Taffy

Posted March 26, 2004 - 08:28 AM

#9

if you have done the end cap (and i've no idea what it is but i know what it means) and opened the airbox the jetting always goes up and from then on it always goes down as you increase the speed of the airflow.

so that 165MJ could do with being about 170-172 i should think. the neddle will definately have to drop after that though.

Taffy

  • simon@vic

Posted March 26, 2004 - 03:17 PM

#10

thx dude.




 
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