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Needle question

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Happy new year all

I am experimenting with a complex pipe, the dreaded SST plus a Vortex ignition set up on my YZ250 year 09. So far I tried out several needles, from Stock @ 48/NP3/190, N8RW @ 48/NP3/185 which runs best but has the lightest gray color on the plug, the NECJ at 48/NP3/175 and latest the NEDJ @ 45/NP3/182. Both suzuki needles have the hick up at low RPM. When in the powerband the bike runs nicely.

The stock needle I even tried once @ 48/NP4/190 but it was way to fat. Still the plug showed almost the same gray color tone like the Suzuki needles. NECJ and NEDJ.

The piston pics are after 40 hours and with the NECJ. Now the top end has 25 hours the underside:

piston-underneath.jpg

and the top of the piston. I run the engine with 30:1 and with 95 octan.

http://arnego2.com/download/last-piston.jpg

Can I run the bike with the needle which is best? The N8RW has no problemes just the plug looks too bright for me. If the N8RW is similar to the NECJ I would do that.

The piston pics look already as if the engine runs lean, maybe too lean.

The plug color I had after putting in the vortex cdi. I put the timing back about 3mm. No change at the plug just a bit less power on the bottom.

thanks

Edited by arnego2
needle name error

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what is your altitude? I ran the sst at 5000 ft with stock needle on my 05 yz250 with no problems.

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I live on Margarita Island, so the altitude about 200 Feet to 500 feets with about 30 degress Celsius.

Vortex says to run at least 50/NP3/180 with the stock needle but apart from the pilot I ran it at 190.

As I cannot get a slim enough spacer to make a NP3.5 on the stock needle I used a Suzuki needle I had.

Edited by arnego2

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Changing the exhaust and silencer to fatty and PC r304 shorty using the needle N8RW with 48/NP3/190 airscrew 1 turn and had the same color than the other needles.

But I might have found the issue, today I had some time and waited a tat so the engine cooled a bit when in the riding area.

Pulling the plug the plug looked wet and brown. So I came to the conclusion that the last 2 miles from the riding area to get home are to blame for the gray color.

Street jetting must be by far richer so it seems to me.

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That sounds right to me, street riding needs extremely rich jetting, Id personally jet for where you spend most of your time riding, which would obviously be in the woods?

You may need to take it pretty easy on the street though. Your def. lean, which may be directly related to your time on the street.

Edited by ftball90

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I live on Margarita Island, so the altitude about 200 Feet to 500 feets with about 30 degress Celsius.

Vortex says to run at least 50/NP3/180 with the stock needle but apart from the pilot I ran it at 190.

As I cannot get a slim enough spacer to make a NP3.5 on the stock needle I used a Suzuki needle I had.

You don't need to make spacers for the needles, just get the needle with is half a clip different.

Also it seems from your posting that you do not move the needle positions, always around 3.

Personally I have my needle set on #1. I have tried tuning with half clip increments.

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I have tried NP4 to get a richer mixture just riding was not a pleasure any more with that setting.

So far I went through 4 needles and the last one is the N8RW which gives me a NP3.5 translated to stock NP.

Good to get a confirmation about street jetting vs offroad. Thanks a lot :bonk: I'll take it easier now on street. It's about

a mile to the place where offorad starts. :smirk:

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With the vortex I did use NP2 but is did give me a lean problem with the piston. Vortex said that you have to use the 50/NP3/180 at least.

When I got th ebike I put it at 48/NP2/172 and it was OK but when you change your riding way, riding harder I went to NP3.

Edited by arnego2

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With the vortex I did use NP2 but is did give me a lean problem with the piston. Vortex said that you have to use the 50/NP3/180 at least.

When I got th ebike I put it at 48/NP2/172 and it was OK but when you change your riding way, riding harder I went to NP3.

I wouldn't worry too much what vortex say, they do not understand you riding conditions or your bike set up. Jet to suit.

You tried the stock needle in Position #4 and notided that it was too fat, what about 1,2 & 3?

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Not really as I did not change the jetting when putting in the vortex. So they were right.

On the stock needle I did try the NP4 and it was too rich IMO now I use the needle N8RW at NP3 = to N3EW NP3.5 to be sure that I don't get another lean seize of the piston which happend when having the NP2 with the stock needle. So far the N8RW works for me.

NP1 I did never try, as NP2 was Ok with the Stock CDI. But the change to the Vortex needed to put the NP to 3 at least.

Now I ride harder than before and riding harder needs a richer jetting so far I know. Here you can have a look of the riding area click here

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