Jetting recommendations 1997 cr 250 with 99 cr 250 PWK AS


11 replies to this topic
  • Rottn1

Posted September 16, 2013 - 03:52 PM

#1

Hi, chasing a starting point for jetting a 1997 cr 250 with 99 cr 250 PWK AS Carby. The bike has Procircuit system ( Platinium & R304), VForce Delta 2 and port matching and burs cleaned and tidied.

 

Pro circuit has specs for the '99 '00 CR 250's same carb on both bikes but Different jetting specs

 

CR 250 '00

Pro Circuit 172 STD STD 2ND 1 1/2

 

CR 250 '99

Pro Circuit 168 55 1370M 3RD 1 1/2         NEEDLE# 16204-K23-690

 

I Live in Australia similar climate to coastal S Cal

 

Thanks

 

Alan



  • frdbtr

Posted September 16, 2013 - 06:56 PM

#2

Hi, chasing a starting point for jetting a 1997 cr 250 with 99 cr 250 PWK AS Carby. The bike has Procircuit system ( Platinium & R304), VForce Delta 2 and port matching and burs cleaned and tidied.

 

Pro circuit has specs for the '99 '00 CR 250's same carb on both bikes but Different jetting specs

 

CR 250 '00

Pro Circuit 172 STD STD 2ND 1 1/2

 

CR 250 '99

Pro Circuit 168 55 1370M 3RD 1 1/2         NEEDLE# 16204-K23-690

 

I Live in Australia similar climate to coastal S Cal

 

Thanks

 

Alan

 

Go with the 99 recommendations.



  • adam8781

Posted September 16, 2013 - 07:24 PM

#3

beat me to it,  PC jetting specs is always a good starting point.



  • Rottn1

Posted September 16, 2013 - 07:26 PM

#4

Go with the 99 recommendations.

Thats my inclination, I will have to go with a 170 main as I cannot buy a 168 main jet locally



  • heart_of_darkness

Posted September 18, 2013 - 04:36 AM

#5

The 1999 carb has a #5.5 slide, which means you'll need slightly leaner low end jetting.  I have the same carb and am running a #42 pilot and the stock #1370DKA needle on the second clip in similar summer temps.

 

The #55 pilot suggested above is extremely rich.  That's the size the old PJ carb would have used.



  • frdbtr

Posted September 18, 2013 - 07:06 AM

#6

The 1999 carb has a #5.5 slide, which means you'll need slightly leaner low end jetting.  I have the same carb and am running a #42 pilot and the stock #1370DKA needle on the second clip in similar summer temps.

 

The #55 pilot suggested above is extremely rich.  That's the size the old PJ carb would have used.

 

True but PC is recommending a different needle so if you go strictly with their settings including the different needle, you had better follow their settings.



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  • Keith72

Posted September 18, 2013 - 09:22 AM

#7

What was wrong with the 97 carb?

  • frdbtr

Posted September 18, 2013 - 10:04 AM

#8

What was wrong with the 97 carb?

 

The Keihin PJ carb on the 97 cr250 is a very good carb.  The PWK from the 99-00 CR250's is a far superior one.  Hard to believe but true.  If it were my bike, I would buy the 7.0 slide and 00 needle  and then run the 00 jetting.  the 7.0 slide much more compatible for a cr250 than the 5.5 slide in the 99 carb.


Edited by frdbtr, September 18, 2013 - 10:05 AM.


  • Keith72

Posted September 18, 2013 - 02:58 PM

#9

The Keihin PJ carb on the 97 cr250 is a very good carb.  The PWK from the 99-00 CR250's is a far superior one.  Hard to believe but true.  If it were my bike, I would buy the 7.0 slide and 00 needle  and then run the 00 jetting.  the 7.0 slide much more compatible for a cr250 than the 5.5 slide in the 99 carb.

 

 

I dont have experience with the 99 carb. However the carb on the 97 I owned was flawless. Thats why I asked. Seemed like a strange unneeded swap.



  • frdbtr

Posted September 18, 2013 - 03:28 PM

#10

I dont have experience with the 99 carb. However the carb on the 97 I owned was flawless. Thats why I asked. Seemed like a strange unneeded swap.

 

I wouldn't make the swap unless the 97 carb was malfunctioning in some way but the Keihin PWK carb is a better carb then the PJ carbs.  You get better throttle response and cleaner running motor with the PWK, it is a surprise but true.  I replaced the 36mm PJ carb that was running really well on my 94 cr144 (eric gorr big bore kit) with a 38mm PWK in order to get more top end power out of the bike and was shocked at how much better the bike ran overall, not withstanding the more top end.



  • Rottn1

Posted September 18, 2013 - 11:50 PM

#11

Ok we are at 170 48 1370M 3RD 1 1/4 TURNS.    Still needs fine tuning hopefully get a few Hours on track towmorrow :)  

 

(Please note the 55 Pilot was WAY to rich, would not idle with it in, it was at about 3 3\4 turns so gave me a rich starting point)

 

I changed the Carby for 2 reasons. 1st the Choke/Idle adjuster on PJ appears on the fritz and 2. the PWK  38 AS   "IS"  a far superior carby

 

Thanks for the input

 

Alan



  • Rottn1

Posted October 29, 2013 - 07:24 PM

#12

Ok I have an update, I tried the Suzuki N3EW Needle, 42 PJ, 170 main @ 11/4 turns and WOW!!!!   it is now so smooth from bottom to top, the power just builds strongly no flat spots,  can not wait to get it on track again to give it a good run :ride:


Edited by Rottn1, October 29, 2013 - 07:25 PM.






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