Jump to content

JD Jetting 38mm PWK Shorty

Recommended Posts

I just got this in the mail. I have a 2017 250 XC-W. The kit does not distinguish between settings for a 250 or a 300 :(

It's 60 degrees at sea level here in San Diego.

Went with the recommended 172 Main, Blue 3rd clip, 42 Pilot (came in the carb), bike runs like garbage from 0 to quarter throttle then she takes off. Very blubbery, lots of pipe bang. Setting the air screw the revs continue to pick up after three full turns out. Seems like I need a smaller pilot. 

I can't find any other threads here where people used this kit and what their settings were? I emailed JD but have not hear back and I'm supposed to ride tomorrow!

Took off my Mikuni which ran quite well (when it felt like it) with a JD kit,  430 main, blue needle third clip - their recommendations. I did drop the pilot from a 32.5 to a 30 and the bike ran much better. 

Put a 38 Pilot in the new carb and she runs better but power is down. I don't have a 40 pilot. Question - should I run the 38, or go with the 42 and either raise the clip on the blue needle or replace with red needle 3rd clip? Sorry for the boring post!!

Share this post


Link to post
Share on other sites

I could never get the JD needle to run how I wanted it to run, pretty much the same problem having to go leaner down low and then it felt anemic. The red needle is a little leaner off the bottom if I recall, you could try that. I like the way the NEC(x) suzuki needles run with the keihin carb, lots of people do because of the strong bottom end.

Share this post


Link to post
Share on other sites

I am running the same carb on a 2017 KTM 250XC. 

I ran 42 pilot, 175 main, blue needle #3, AS at 2. 100FT ASL, temps 50-65F. 

Pump gas @ 50:1.

The above setting were ran at Ocotillo Wells. If you are in San Diego you know where that is.

Ran great, I do have an RK Tek head however which helps dialing in jetting, and uses slightly richer jetting.

 

**If you have a stock head..I'd run red #3, pilot at 42, main at 172.

 

Edited by shrub73

Share this post


Link to post
Share on other sites

2017 300 + RK head + 38 keihin from JD.

Recently ran 42PJ, red 3, 172 main in the SoCal high desert from 2500-7000 ft. Very linear. Cannot find a fault in it. Maybe a bit lean on the main circuit on the big sandy hill climbs of SoCal. I've had good results with this setting at sea level in Norcal as well.

Prior to the temps dropping, I was running 38PJ, red 3, 170 main from 3-8K elevation (65-100 degrees) with good results as well.

I would follow Shrub73's suggestion of 42 pj, red 3, 172 main, AS 1.5, and go from there.

Share this post


Link to post
Share on other sites

Than you all SO much for the replies. 

I have a confession to make/ I had a realization. I don’t fully dry my filters before I add oil. I figure the oil displaces the water, at least that’s what it seems to do when I squeeze them out. Had a fresh filter in there for the new carb, and although it felt dry - it dried overnight - i think the oil may have locked some dampness in which mad the bike run rich. Anyway I put the 42 pilot back in with red needle in third clip and let the bike fully warm up again and she seems a lot better plus the temps dropped 10 degrees. I’ll confirm how things are running after riding on Sunday. 

  • Like 2

Share this post


Link to post
Share on other sites

I got the same carb for my Beta 300 3 years ago to replace a Lectron. Night n day difference (have since sold her).

Your jetting actually sounds right - you don't want to run much leaner in a 38 PWK. 

  • Like 1

Share this post


Link to post
Share on other sites

I run the same jetting on my 17 250xc, other than I run the Suzuki NEDW needle.  Bike runs great, and, always dry your filter before you oil them!  But...you know that now.

Share this post


Link to post
Share on other sites

I tuned my 2019 300xc using a JD kit.

I didn’t like the suggested pilot. The kit called for two sizes bigger than factory installed pilot. So I put that back in and she ran great!

25 p
440 m
Red needle 3 clip
Aso 1 @ sea level to 2000 feet

Then all I have to do is wind out the air screw another 3/4, and I’m good up to 4500 feet. I love it.

Share this post


Link to post
Share on other sites

2017 TX300 1000' ASL with 36mm Keihin and just installed RK Tek head.  Prior to the head I had been running jd red #3, 40p 168m with good results.

Kelsey recommended going much richer.  Today I will be trying 42p 178m with his recommended N8RG needle.  This is the same needle that came in the 2015 300 which also had the 36mm Keihin.

I will report back later.

Share this post


Link to post
Share on other sites
5 hours ago, WoodsRacerDotCom said:

2017 TX300 1000' ASL with 36mm Keihin and just installed RK Tek head.  Prior to the head I had been running jd red #3, 40p 168m with good results.

Kelsey recommended going much richer.  Today I will be trying 42p 178m with his recommended N8RG needle.  This is the same needle that came in the 2015 300 which also had the 36mm Keihin.

I will report back later.

All I can say is WOW!  Now I understand all the claims of 1 to 2 gears higher with the RK Tek head!  At first I was a little disappointed but listened to Kelsey about going very rich with the jetting and I am a happy camper now!  It does have a bit of a rich gurgle right off the bottom, but it pulls so nice and smoothly I don't think I'm going to mess with it unless I have to.  Not only does it lug better but it is smooth tractable power approaching four stroke levels!  

Share this post


Link to post
Share on other sites
On 12/29/2018 at 12:20 PM, WoodsRacerDotCom said:

All I can say is WOW!  Now I understand all the claims of 1 to 2 gears higher with the RK Tek head!  At first I was a little disappointed but listened to Kelsey about going very rich with the jetting and I am a happy camper now!  It does have a bit of a rich gurgle right off the bottom, but it pulls so nice and smoothly I don't think I'm going to mess with it unless I have to.  Not only does it lug better but it is smooth tractable power approaching four stroke levels!  

Very interesting with the huge jump in MJ size. I should try this myself as I'm running the same head. Maybe the gurgle can be cured of the bottom with pilot or needle?

My report - carb working much better, moral is dry your filters before oiling them! Doesn't pull any harder than the Mikuni when the Mikuni was running well, but that's fine - just hoping the jetting will be less volatile with temps and elevation. 

  • Like 1

Share this post


Link to post
Share on other sites
7 hours ago, sammyd173 said:

Very interesting with the huge jump in MJ size. I should try this myself as I'm running the same head. Maybe the gurgle can be cured of the bottom with pilot or needle?

My report - carb working much better, moral is dry your filters before oiling them! Doesn't pull any harder than the Mikuni when the Mikuni was running well, but that's fine - just hoping the jetting will be less volatile with temps and elevation. 

Much more stable carb, that's the real benefit in the swap.  Glad you're getting close.

  • Like 1

Share this post


Link to post
Share on other sites

well, my fuel mileage is way down with the 42/178, but low end torque is off the charts!  I might try and drop the pilot to a 40 and see if that helps any.  Last ride I got 31 miles before reserve.  

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×