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PWK Jetting cr250 06

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Hi guys, Im looking for some suggestions for jetting a PWK Airstryker carb on my 2006 cr250. The carb was from an 03 kx250 and came with a #8 slide and NAFF needle. Im running a PC pipe and silencer, v-force 3 reeds and mainly ride single track around 0-1000m. Cheers for your help:thumbsup:

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I'll give you a couple of options for the #8 slide.

1--very responsive and clean, Suzuki NECH in clip #2, 42 pilot, and 172 main, AS@ 1.5 turns out.

 

2--little stronger off the bottom and into the middle, Yamaha N3CW in clip #3, 45 pilot, 178 main, AS@1.5 turns out. 

These are starting points for temps in the +60 deg F

 

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On April 12, 2018 at 8:04 PM, Ben Mcnamara said:

Thanks for your quick response. I'll give the first set up a try. Is that based on 93 pump fuel?

Yes, either setup will work with pump fuel.

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On 4/12/2018 at 6:04 PM, Ben Mcnamara said:

Thanks for your quick response. I'll give the first set up a try. Is that based on 93 pump fuel?

Did you try the NAFF needle it came with?

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...to add some jetting spice into the mix....

For slow single track riding, ie, averaging 20-25 mph typical of most enduro type stuff, I like my jetting tb on the rich side in the low to mid revs to get me more traction with loose, slippery hill climbs and smoother pulling power as I'm snaking through tight trees . In many tight technical sections and rocky climbs I ride on, a crisp throttle -one that cleans out quick for acceleration through the more open stuff - unfortunately will  have my front wheel coming off the ground everytime I throttle through the tough stuff. 
Needles that starts out richer earlier in the throttle opening and then tapers more lean later in the throttle opening works better for single track riding w/ the tough technical rocky slick hill climbs thrown in b/c they don't seem to be as abrupt as they transition into getting on the pipe. I find the single taper needles better vs. the double and triple needle tapers like the NAFF, NECH, N3CW. Nothing wrong w/ those if that's what you want, but imo the double and triple tapers are better if you ride more open single tracks where you're getting on the pipe more frequently.

The two straight taper "woods friendly" needles I've used for slow single tracks on my '05 is:

Sudco DCK for the 38mm pwk

Sudco DDK for the 36mm pwk

Note: premix ratios are between 40-50:1, and the premix I use for slow woods riding is a light/thin viscosity premix to eliminate excess spooge for riding that's mainly under the hit of the pipe. I try not to use premix that says "Racing premix" as these are often thicker viscosities made to work at higher rpm and won't evaporate quickly at higher cyl temps. But there's nothing wrong w/ using race premix for woods, except I see more spooge coming out the pipe when I don't ride it hard.

 

 

 

 

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On 4/12/2018 at 0:13 AM, Ben Mcnamara said:

Hi guys, Im looking for some suggestions for jetting a PWK Airstryker carb on my 2006 cr250. The carb was from an 03 kx250 and came with a #8 slide and NAFF needle. Im running a PC pipe and silencer, v-force 3 reeds and mainly ride single track around 0-1000m. Cheers for your help:thumbsup:

 

On 4/12/2018 at 0:44 AM, rtv said:

I'll give you a couple of options for the #8 slide.

1--very responsive and clean, Suzuki NECH in clip #2, 42 pilot, and 172 main, AS@ 1.5 turns out.

 

2--little stronger off the bottom and into the middle, Yamaha N3CW in clip #3, 45 pilot, 178 main, AS@1.5 turns out. 

These are starting points for temps in the +60 deg F

 

i can honestly say that these suzuki needles are awesome , rtv put me on to them and i have never looked back

i currently run 42 pilot , NEDJ clip 2 with my stock main with the #8 slide and bike runs clean from idle to WOT with no hesitations 60 deg f to 105 deg f

all that is required is an Air Screw adjustment . i run 50:1 with full synthetic low flash point oil and the bike blows minimum smoke and zero spooge ever

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Ben , good luck with the swap. Keen to know how it goes for you.

The mikuni TMX (even with JD kit) seems to need constant adjustment, I have been fixing/tuning bikes and classic cars for years , so no stranger to jetting but this carb has got me beat. :banghead:

I own a '06 cr250 with cylinder and head mods and have purchased a Keihin airstriker off a 2003 kx250 for my bike.


The TPS will be disconnected and the powerjet circuit will be blocked. Using kx throttle ass. and cable (honda cable too short)

RTV and others have a lot of good info , so will be trying his suzuki needle recommendations for trail/woods riding.

Seems a lot of people sort out their gen3 CR's with the airstriker swap .

 

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Ben , good luck with the swap. Keen to know how it goes for you.
The mikuni TMX (even with JD kit) seems to need constant adjustment, I have been fixing/tuning bikes and classic cars for years , so no stranger to jetting but this carb has got me beat. :banghead:
I own a '06 cr250 with cylinder and head mods and have purchased a Keihin airstriker off a 2003 kx250 for my bike.

The TPS will be disconnected and the powerjet circuit will be blocked. Using kx throttle ass. and cable (honda cable too short)
RTV and others have a lot of good info , so will be trying his suzuki needle recommendations for trail/woods riding.
Seems a lot of people sort out their gen3 CR's with the airstriker swap .
 


I have a 2003 and 2002 cr250. The 03 has a PWK and the 2002 the TMX. I use RTV’s jetting specs for the 2003 w/PWK and it is awesome in the woods with the Suzuki needles! I do however like the TMX on the 2002, but made sure the squish was cut and jetting tuned. I don’t find it to be that finicky, but I keep my riding from sea level to 1500’.

My opinion is that for track, I would go with the TMX, and off road, the PWK with Suzuki needle.

Seems to be much hate for the TMX, but I’ve found, just as with the case reed motors, you need to do your due diligence with setup. Once that is sorted, the bike just flat out rips!

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Yea , no worries with performance - bike is a beast. Pulls hard off the bottom, good mid range and top end rips.

Splooge and plugs that got me beat. 

I ride woods/offroad and get plug fouling in the real slow stuff. Did 3 rides - all good, then one muddy ride (lots of 1st and 2nd gear stuff)

and fouled 2plugs (BR8EG).

Seems to load up quick when not "on the pipe". I like this bike man , hope the airstryker help with this issue.

 

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On my 05 CR250 with the air Stryker from a YZ, it did make a positive difference once the TPS was connected.

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Interesting post GB1073, how much difference and where ??  some aftermarket carbs have no TPS.

I thought I'd be ok with it unplugged. :excuseme:

Will hook it up if there is any chance of losing performance.

 

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Thanks Jeddclampette and RTV for posting useful guidelines  :thumbsup: 

The 38mm PWK is installed on the CR (no TPS ) , using a KX cable and motion pro throttle assembly.

45 pilot - NC3W needle, 3rd clip - #175 main (all I could get, have ordered a #178 as recommended) , AS 1.5 turns

 

Holy S..... what a difference!   Starts 1/2 kick (never done that b4) 

Less splooge, and will lug to almost stalling point   :ride: 

Plug Chop Test when larger main installed,

Hopefully the OP gets the same results as I did  -- TT rocks

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RTV knows what he is talking about. I have used a bunch of his jetting recommendations.  I have used the N3CW needle but I ride at 4500 feet above sea level and higher so I settled on the N3EJ needle for a while because it works better at my altitude.  That needle needs the #7 slide though so it wouldn't help you much.  I finally settled on the Suzuki/Kawasaki N3WJ needle and I love it.  I don't know if you can use that needle with the #8 slide at your altitude but my 06 loves it at my altitude.  The bike is crisp and clean from idle and revs to the moon. 

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If you have the cash you could always opt for a lectron carb? Take all the hassle out of it for easy faff free riding. 

Edited by Martin King

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What's up guys. Lots of good info in this post. Was wondering if maybe I could get some help with mine.

I have an 06 cr250 with Eric gore porting, squish has been fixed, with high compression, vforce reeds, gnarly pipe with shorty silencer. 10 oz flywheel weight Currently running sunocco 110 but usually run straight c-12. 38mm airstryker. About 500' to 2000' above sea level

Race harescramles and enduros

Jetting currently is
180 main
Blue needle with clip in very top position
50 pilot I believe
The slide that came with the carb from jd
Temps 80+ right now.

I'm having issues getting it to run clean in the middle. Off idle is good top end is good

I've tried red and blue needles in all positions and richer and leaner mains. Have not put a leaner pilot in yet as I haven't had time to a whole lot of testing. Been super busy this year and only have been able to make it to the races.

When orders the carb from jd I sent all my info with it hoping to get it baselined but it wasn't even close. When I talked to them they said they don't pre Jett any more.

Can't seem to get it to not load up in the middle. I know I have a pretty rich main in it for the race fuel but it does the same thing no matter the main. I went down to a 170 and it just felt too lean so I'm staying on the safe side for now.

Any of you guys have experience with the race fuel and porting. My other stock bikes I've had were easy to get right. This is my first time jetting with the race fuel and porting at the same time.

I read in another forum that I might need the dgh needle that is a little longer.

Any info will help thx

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