Just got my YZ needle. Any suggestions?

I am going to try the yz needle in my WR450. I am currently running with all the free mods done a 160 main, 50 pilot, 1-1\2 turns out on fuel screw, and stock needle in 4th position. elevation 1000-3000 ft. Any one have a suggestion for a starting point?



Uncork your pipe and you should be close with the needle in clip #4.


Wassup with the YZ needle? You hold'in out on me?


Indy, you are referring to the YZ needle in the 4th position right? Pipe is already uncorked and the bike runs real well. Just thought I would see if there is any thing else in there. I need something to be able to compete with the Jimmy tube. :)


Not an expert, this board helped me alot. Mine ran rich with anything other than close to stock YZ jetting with the EKP needle. See my sig. for jetting. I believe EKP needle is a little richer than the YZ needle. Your pilot seems a little rich. Again, I am no expert. I only followed the advice of this board and started out in the right direction.

OK, I think I'll start with the stock YZ jetting. It seems kind of strange that the standard pilot jet for the YZ is one size smaller than the one for the WR. #42 for YZ and #45 for the WR. It must be because of the differances in the needle and the way bigger main jet. :)


Yes, you are right, it is because the YZ needle is much more agressive than the "D" WR needle. This logic has eluded many people including the previous owner of my bike. Most people put in the YZ or EKP needle and move up a few sizes in jets. This throws everything off, way too rich. My bike had a EKP needle in 4th position, a 68 pilot and a 172 main. It was way rich and would miss under rollon throttle (from 0 to 1/2). See my sig. for what works much better now.

Wrkaholic is right the needle taper plays a lot into the size of your main jet. The more aggressive tapers use a smaller main jet. There seems to be different strategies but with most of the mods TT members are doing, I favor dropping the stock needle which has a mild taper and going to a more aggressive and richer needle. :)

I think the WR450 and the WR426 are jetted differently.

Indy did you put your YZ needle back in ??? I took mine out when it got over 65 degrees F. My bike was running way to rich. If I ever get a chance to ride again I might find out how it runs with the temps in the 70/80's :) July is the projected date to be done with training. Hope to ride with you in Attica. :D

The carb bodies are slightly different.

Hey Scott, I am on the YZ needle NDJN and will be switching when it gets hot to a P needle. It still has been cold around here. We have yet to have hot weather this year. It has been an unseasonably cold spring. The thunder alley pipe does not like the stock needle. Attica in July will be good when I get back from Colorado. Gone from July 3rd to the 14th. Talk to you later. :)

I ran the stock YZ jetting on Sunday and was pleased. Seemed to really liven up the mid range. Off idle performance was great. Rode up to 6000 feet and was a little rich up that high but not terrible. As the day grew warmer it lost a little performance so I think I'll try lowering the needle one position for the next ride as the weather is getting warmer here. May need to go to the next leaner needle when it gets real hot. It still kind of baffles me as to why the stock YZ pilot is smaller than the stock WR pilot. I was running a 50 with the WR needle and 160 main. Now its a 42 pilot with a 162 main for the YZ needle.


it's really quite simple the difference between a 'D' taper needle and an 'E' taper needle is that the needle taper on the 'D' starts a lot higher up the needle it then crosses a point in the middle of the needle that none of us can see and comes to a fat blunted end.

in the meantime the 'E' taper needle starts a lot lower and a lot later. 4mm anyone?

it cuts straight down and in to a point. this means my frinds that for a short distance the 'D' series is a thinner needle!!!!!!!!! and that friends, is the bit right where the pilot jet works!

thinner needle = needs smaller pilot jet.

just try to think of a wide based cone that cuts in to a pencil point and another that has a narrower base and comes to a fat blunted end.

remember that until you understand it all you don't understand any of it (i think, er maybe) :)



Thanks for the insight Taffy, I always suspected that the pilot circuit and needle overlapped a lot more then others have said on this forum. :)

yep, just so's everyone knows the needle isn't important here, it's not even what you set the bike up by. treat it as a cake and the icing is the PJ. it takes a change in taper just to change 1 pilot jet number so it doesn't happen everyday.

the problem with the 'D' taper is that if it is on clip 1, 2 or 3 the damn taper start is so low in the hole it can cause a slight bog.

the answer is funnily enough right up the other end. if you lean the MJ off the needle needs lifting. this is why when you read jetting Qs you'll note that there are dozens of jetting changes going on but that the bloody needle bobs up and down like a float on the river!

thus my dig at yami the other night.


E taper and D taper? How do I convert those to what Yamaha has listed for the WR450 and the YZ450? All I know is that the WR needles are listed like OBDUQ and the YZ needles are NCVQ and so on.

Also, can any one tell me what the standard pilot air jet is on the WR450's. I guess I can take it out and look.


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