What is the difference from the RED and BLUE JD NEEDLE???

[jetpilot2002]

Does anyone know what the difference is between the RED and BLUE JD NEEDLES??? Does one give you more low end and one give you more high end? I ride around 4k-5k and do not know which one to use. Any information would be great. What have you found out to work the best?

[Chas_M]

The blue and red needles are the same, except the red needle has a slightly greater diameter (leaner) at 0 - 1/4 throttle. In my 525 EXC, I prefer the red needle #3, 170 main jet at elevations above 3,500 feet.

[REDCHIP]

Per his instructions, the blue is for under 50 degrees and the red is for over 50 degrees.

[saucebox]

blue ones are for yami's and red ones are for hondas

[jetpilot2002]

So is the red needle give you more top end WOT and the blue one give you more low end?

[Chas_M]

Since the red and blue needles are the same from roughly 1/4 to 4/4 throttle, the top end response and WOT should be the same or at least very similar for both needles. At higher elevations, I find that the red needle provides better low speed response and therefore a better lowend.

[jetpilot2002]

I tried the blue needle and really did not like it, it has ok 1/4-1/2 throttle but 0-1/4 was not very clean and it would hesitate. WOT I felt was about the same as stock, but I thought stock might of been a little better holding the r's up the hill. Maybe I will try the red needle. Stock I was a 165 main jet, 4th clip and then I tried the blue needle third clip 178, that was to rich, 175 better, 172 about the same as 175 but I felt it struggling at WOT, like it was lean and after checking the plug it was. So what should I try with the red needle? What main jet and on was clip? Thanks for your help.

[superslyko]

Come on guys!?

Read the instructions that came with the kit! Do some thinking...........all you're questions are answered there! He even explains the steps to take with the needles and the clip position.

[jetpilot2002]

Come on guys!?

Read the instructions that came with the kit! Do some thinking...........all you're questions are answered there! He even explains the steps to take with the needles and the clip position.

I did do what his instructions said and the bike ran like crap, that is why I am asking for help.

[Ga426owner]

Does anyone know what the difference is between the RED and BLUE JD NEEDLES??? Does one give you more low end and one give you more high end? I ride around 4k-5k and do not know which one to use. Any information would be great. What have you found out to work the best?

You are looking at this wrong - please come back JD!!!!!!!!!!

The difference in needles solely is for changes in temp and altitude - NOT LOW / HIGH END.

What temps are you riding in? At 4-5k elevation which needle does the instructions say to use and which main -

For me altitude = 900-2500ft

I use the Blue needle with a 170main or a 168main in my blue 450 for temps ranging 45 -69 (larger main = colder temps 45-55 approx)

I use the Red needle for all temps above 70 with either 170 or a 168 (168 seems better in hotter/humid temps above 85)

hope this helps

[Domenic_WRF]

If your above 4,000 feet with temps above 50 degree's the red needle may work better for you..Start with JD's recommended main jet..The 450's seem to like clip 5 on the red..Only way to test the main is WOT in forth or fifth If it still bog's 0-1/4 throttle a leaner pilot or bigger leak jet may be in order..The Red needle cleans up low end responce in these bikes when winters over..Good luck

[jetpilot2002]

I finally got to ride and I put the red needle in on the 5th clip and WOW what a differerence it made with the throttle response, it was a lot cleaner and crisper, I think I might have had one step to high main jet, so I am going to go down one and see if it makes it any better. The red needle at 4k elevation and about 55 degrees was a lot better then the blue needle. Thanks guys for all the help.

[kelstr]

thats correct the needles are for a different range due to temp and altitude,

has nothing to do with low end or top end, its what kinda air do you have at the time .

they both are designed to keep the bike in a close state of tune with each other depending on what kinda air and what kinda track.

when your at sea level and its 45 degrees out 15 % humidity, the blue on 3rd with a 180 makes the thing a monster, i just love it , but ------its because the air is heavy and there is lots of oxygen to mix and burn,

most of the time in az where I'm at you can't use the blue, I'm 1250 feet at 100 degrees at 10% humidity i have to run red 3 clip and a 175 main,

and alot also depends on fuel , with normal leaded race fuel ( not u2 or u4 , thats another discussion ),

but i will be red 2nd clip 168 main 40 pilot with no squirt at all , and the thing runs great,

it doesn't run as good as when its cold with the blue needle , but of course not , it can't

there is not the same oxygen in the thin air , ------so thats all the needles are for ,

just to keep the thing running crisp depending on where and what and why,

thats what james is explaining in his instructions !! ?

[motomike137]

kelstr, you mentioned two things in your post that interest me. You say that with leaded race gas and the right jetting you completely disable the ac pump?

[kelstr]

yes since the first 98 yz 400f thing that the public got i have almost shut it off for most riders , and so has every body else, when jimmy button got henry's thumper jimmy could not deal with it and it was shut off,

i have always not liked the dam thing, and with real fuel and careful tuning you dont need the thing,

most the pros dont run them

even on pump fuel you can get away with .2 or .3 tenths of a second witch is almost none.

its really not that big of a deal either way( i think they can run cleaner and be jetted more spot on without the thing) , it just depends on not only track but rider,

on some of the tight tracks in the heat of the summer you can dam neer start to load the thing up because you are constently wacking the throttle

every 50 or 75 feet and the bike starts to spudder and not keep clean because its so overfueled , all your doing is adding more and more and putting out the fire ? ,

and if you ever noticed when you slowly roll on the throttle the ap dosent squirt anyway,

some guys dont even know they are barley using it at all.

so no i am not a fan of the slopy ap circut.

[jetpilot2002]

One last question, if I am going downt the road at WOT and then I let off the gas and de-excelerate and I get popping/backfiring, what would I need to do to fix/solve that. Is it too rich, too lean?

[kelstr]

your slow speed circut in lean, ( the germans call it a slow jet , the japs call it a pilot jet , the brits and americans call it a idle jet).

what you need to do is to open up your fuel screw to ritchen up the pilot circut some and retest,

it has nothing to do with the ap .

now you also have to make sure your not pulling air in through a leaking exhaust flange gskt or slip conection,

the pilot circut even with a large 45 pilot at 3 turns out cannot overcome sucking air into the exhaust and it will also give you this poping !!