Posts: 31
Joined: 2/12/2019
Location: Simi Valley, CA USA
I need to jet this 2006 yz250 I picked up.It runs rich and is fouling plugs. I know someone on here has the titty set up. Please share!
Bike specs:
FMF gnarly pipe with turbine core sparky
vforce3 reed valve system
Premix is 50:1 Motul 800 2T
I am in southern California and ride in elevations between 500 - 2500 ft.
It currently has a 52 pilot and the main is unknown(No label found - Does that mean it's stock?). I haven't checked the needle yet.
Posts: 536
Joined: 4/1/2008
Location: Upstate, NY USA
layenpipe25 wrote:
I need to jet this 2006 yz250 I picked up.It runs rich and is fouling plugs. I know someone on here has the titty set up. Please share!
Bike specs:
FMF gnarly pipe with turbine core sparky
vforce3 reed valve system
Premix is 50:1 Motul 800 2T
I am in southern California and ride in elevations between 500 - 2500 ft.
It currently has a 52 pilot and the main is unknown(No label found - Does that mean it's stock?). I haven't checked the needle yet.
Needle--Suzuki NECJ in the #3 clip position https://www.rockymountainatvmc.com/oem-schematic/2
Pilot Jet--42
Main--172/170
Power Jet---40 https://www.rockymountainatvmc.com/parts/keihin-n424-52-series-leak-jet-p The 2t power jet is the exact same jet as a 4t leak jet. Same exact jet, two different names.
Air Screw---1.5 turns out
Posts: 8
Joined: 9/22/2018
Location: GBR
178 main , 48 or 50 pilot. 2nd clip on needle. Ditch the turbine core if you dont need it.
Should put you in ball park and not risk being on the lean side.
Posts: 151
Joined: 7/17/2018
Location: West bend, WI USA
Posts: 1327
Joined: 3/12/2012
Location: The Woodlands, TX USA
layenpipe25 wrote:
I need to jet this 2006 yz250 I picked up.It runs rich and is fouling plugs. I know someone on here has the titty set up. Please share!
Bike specs:
FMF gnarly pipe with turbine core sparky
vforce3 reed valve system
Premix is 50:1 Motul 800 2T
I am in southern California and ride in elevations between 500 - 2500 ft.
It currently has a 52 pilot and the main is unknown(No label found - Does that mean it's stock?). I haven't checked the needle yet.
digger wrote:
Needle--Suzuki NECJ in the #3 clip position https://www.rockymountainatvmc.com/oem-schematic/2
Pilot Jet--42
Main--172/170
Power Jet---40 https://www.rockymountainatvmc.com/parts/keihin-n424-52-series-leak-jet-p The 2t power jet is the exact same jet as a 4t leak jet. Same exact jet, two different names.
Air Screw---1.5 turns out
Listen to this guy, he knows his stuff.
2018 KTM 250sx
Instagram CamaroAJ
Posts: 31
Joined: 2/12/2019
Location: Simi Valley, CA USA
layenpipe25 wrote:
I need to jet this 2006 yz250 I picked up.It runs rich and is fouling plugs. I know someone on here has the titty set up. Please share!
Bike specs:
FMF gnarly pipe with turbine core sparky
vforce3 reed valve system
Premix is 50:1 Motul 800 2T
I am in southern California and ride in elevations between 500 - 2500 ft.
It currently has a 52 pilot and the main is unknown(No label found - Does that mean it's stock?). I haven't checked the needle yet.
digger wrote:
Needle--Suzuki NECJ in the #3 clip position https://www.rockymountainatvmc.com/oem-schematic/2
Pilot Jet--42
Main--172/170
Power Jet---40 https://www.rockymountainatvmc.com/parts/keihin-n424-52-series-leak-jet-p The 2t power jet is the exact same jet as a 4t leak jet. Same exact jet, two different names.
Air Screw---1.5 turns out
Wow this is a pretty significant change. Not going to lie, a little scared to throw this combo in right off the bat.. mostly due to the fact that I am riding the desert tomorrow and won't be able to make any changes in the case it doesn't pan out. That suzuki needle is something that will have to be ordered. My local shop only has the jets in stock. Can you recommend a jet only set up, progressesing toward your intial recommendation for my ride tomorrow?
Posts: 536
Joined: 4/1/2008
Location: Upstate, NY USA
Edited Date/Time:
layenpipe25 wrote:
Wow this is a pretty significant change. Not going to lie, a little scared to throw this combo in right off the bat.. mostly due to the fact that I am riding the desert tomorrow and won't be able to make any changes in the case it doesn't pan out. That suzuki needle is something that will have to be ordered. My local shop only has the jets in stock. Can you recommend a jet only set up, progressesing toward your intial recommendation for my ride tomorrow?
The jetting changes I listed above are designed around that Suzuki triple taper needle. The duel taper needle(N3CW) that is currently in your bike requires different jetting. If you only want jetting around your current needle, I would start by putting the needle, N3CW, in the #2 clip with a 48 pilot, and a 175 main jet. Ideally the bike needs the power jet changed to a 38 with this setup. Regardless of which needle you use this bike really likes having a leaner slide. Your current slide is a #7, the bike runs much cleaner with a #8
. https://jdjetting.com/product/jdkh13-keihin-pwk-carburetor-slide-size-8/ The #7 can also be cut into a #8 fairly easily and cheaply.
Posts: 31
Joined: 2/12/2019
Location: Simi Valley, CA USA
Edited Date/Time:
digger wrote:
Needle--Suzuki NECJ in the #3 clip position https://www.rockymountainatvmc.com/oem-schematic/2
Pilot Jet--42
Main--172/170
Power Jet---40 https://www.rockymountainatvmc.com/parts/keihin-n424-52-series-leak-jet-p The 2t power jet is the exact same jet as a 4t leak jet. Same exact jet, two different names.
Air Screw---1.5 turns outlayenpipe25 wrote:
Wow this is a pretty significant change. Not going to lie, a little scared to throw this combo in right off the bat.. mostly due to the fact that I am riding the desert tomorrow and won't be able to make any changes in the case it doesn't pan out. That suzuki needle is something that will have to be ordered. My local shop only has the jets in stock. Can you recommend a jet only set up, progressesing toward your intial recommendation for my ride tomorrow?
digger wrote:
The jetting changes I listed above are designed around that Suzuki triple taper needle. The duel taper needle(N3CW) that is currently in your bike requires different jetting. If you only want jetting around your current needle, I would start by putting the needle, N3CW, in the #2 clip with a 48 pilot, and a 175 main jet. Ideally the bike needs the power jet changed to a 38 with this setup. Regardless of which needle you use this bike really likes having a leaner slide. Your current slide is a #7, the bike runs much cleaner with a #8
. https://jdjetting.com/product/jdkh13-keihin-pwk-carburetor-slide-size-8/ The #7 can also be cut into a #8 fairly easily and cheaply.
The stock needle in my bike is N3EJ.
My bike was running rich and my local shop only had a few jets in stock for my weekend ride so I went with a 48 pilot from a 52, 178 main(stock), and needle set to 2nd clip. It definitely improved and ran more crisp but when letting off full throttle it would wined out making a dinggg...dinggg...dingg. Does that mean I am running lean on the needle? The low seems to be fine... But my plug shows I am running lean somewhere as the electrodes appear to be getting really hot. Still getting a good amount of splooge out the exhaust. Would switching to the popular N3EW improve on this? 
Posts: 1327
Joined: 3/12/2012
Location: The Woodlands, TX USA
Posts: 9032
Joined: 7/6/2015
Location: Santa Clarita, CA USA
I'm honestly running stock jetting, C12 mixed 40:1 and my 05 runs perfect!
2017 RMZ450
2005 YZ250-sold :,(
1998 YZ250
2005 KX250F
80% of the time it works every time
IG @hammerfamily_4 & @2HRacing
Thanks to : Factory Effex, N2Dirt, Acerbis, DT1, Fasthouse, Matix, FMF, ASV, 100% & Mika Metals
Posts: 536
Joined: 4/1/2008
Location: Upstate, NY USA
layenpipe25 wrote:
Wow this is a pretty significant change. Not going to lie, a little scared to throw this combo in right off the bat.. mostly due to the fact that I am riding the desert tomorrow and won't be able to make any changes in the case it doesn't pan out. That suzuki needle is something that will have to be ordered. My local shop only has the jets in stock. Can you recommend a jet only set up, progressesing toward your intial recommendation for my ride tomorrow?
digger wrote:
The jetting changes I listed above are designed around that Suzuki triple taper needle. The duel taper needle(N3CW) that is currently in your bike requires different jetting. If you only want jetting around your current needle, I would start by putting the needle, N3CW, in the #2 clip with a 48 pilot, and a 175 main jet. Ideally the bike needs the power jet changed to a 38 with this setup. Regardless of which needle you use this bike really likes having a leaner slide. Your current slide is a #7, the bike runs much cleaner with a #8
. https://jdjetting.com/product/jdkh13-keihin-pwk-carburetor-slide-size-8/ The #7 can also be cut into a #8 fairly easily and cheaply.layenpipe25 wrote:
The stock needle in my bike is N3EJ.
My bike was running rich and my local shop only had a few jets in stock for my weekend ride so I went with a 48 pilot from a 52, 178 main(stock), and needle set to 2nd clip. It definitely improved and ran more crisp but when letting off full throttle it would wined out making a dinggg...dinggg...dingg. Does that mean I am running lean on the needle? The low seems to be fine... But my plug shows I am running lean somewhere as the electrodes appear to be getting really hot. Still getting a good amount of splooge out the exhaust. Would switching to the popular N3EW improve on this?
From what you are describing, it sounds like a run on idle which is caused by a lean condition. If your bike is good mechanical condition a 48 pilot jet will not run lean with that series needle. The easier thing to do would be to richer the clip position from, the current #2 to the #3 or #4. If that doesn’t work go to the next richer diameter needle, which would be an N3CW as far as you’re concerned.
