Two Stroke Motocross

Two Stroke Motocross Forum => Technical => Topic started by: luthier269 on June 20, 2012, 10:23:38 PM

Title: 38 PKW Airstrike Carb from JD jetting
Post by: luthier269 on June 20, 2012, 10:23:38 PM
I have a 2005 Cr 250 I see people have swapped out the stock carb for the 38mm  PWK carb. Question the stock carb has a  TPS sensor does the new carb have one also?
Title: 38 PKW Airstrike Carb from JD jetting
Post by: luthier269 on June 21, 2012, 04:02:13 AM
?????
Title: 38 PKW Airstrike Carb from JD jetting
Post by: Jeram on June 21, 2012, 04:58:00 AM
no TPS on the air striker.

if you want a large keihin with TPS, get a 39mm TPS from a late model RM250... cheap on ebay.

if you want to make them perform even better you can taper bore them out to 39/41.5 oval bore.
These carbs also have a powerjet solenoid which the airstriker does not.
Title: 38 PKW Airstrike Carb from JD jetting
Post by: Jeram on June 21, 2012, 05:00:48 AM
but if your hung on the idea of the air striker you can either just disconnect the TPS but this will mean that you will have full throttle powervalve openings and ignition timing ALL THE TIME.

Or simply install a TPS from an RGV250 that isnt connected to the carb.. eg: throttle cable goes to TPS and then another cable goes to the carb.


but If I was you, just buy a $50-100 PWK39 from the RM, thats what I use on my CR250 road racer.
Title: 38 PKW Airstrike Carb from JD jetting
Post by: arnego2 on June 21, 2012, 06:30:50 PM
Quote from: Jeram on June 21, 2012, 11:58:00 AM
if you want a large keihin with TPS, get a 39mm TPS from a late model RM250... cheap on ebay.

I got a '08 RM250 PWK here and wonder:
first how I do connect it to the YZ250 '09 I plan using it in and
second what would be the benefit vs the stock's PWK s?

Sorry for the highjacking  :-[
Title: 38 PKW Airstrike Carb from JD jetting
Post by: Jeram on June 22, 2012, 03:03:52 AM
theoretically it should fit, but what do you intend to gain from doing this?
I couldnt see any gain switching from a large bore pwk to a large bore pwk.

if you want bigger, just bore it out to 41.5
Title: 38 PKW Airstrike Carb from JD jetting
Post by: scotty dog on June 22, 2012, 11:32:09 AM
What are the benefits of putting the RM carb on the CR? I have an 05 CR 250 as well  ;D
Do you know what other mods can be done to the CR to get it really goin Jeram??
Title: 38 PKW Airstrike Carb from JD jetting
Post by: arnego2 on June 22, 2012, 12:23:40 PM
The RM 250 car is a 39mm and the YZ's carb a 38mm I think so 1mm could make a difference, that at least is what I'm hoping.
Title: 38 PKW Airstrike Carb from JD jetting
Post by: Jeram on June 23, 2012, 02:42:31 AM
it wouldnt be much of a difference, but if the carbs swap it'l only take you a few momments to find out.

you will need to rejet, go atleast 1 size bigger than whats in your stock carb and then work your way down till you get the jetting right.
Title: 38 PKW Airstrike Carb from JD jetting
Post by: arnego2 on June 23, 2012, 04:04:25 AM
Thanks
I run the bike with vortex cdi and JD kit with the needle being on the 4rth, so mostlikely I stay with the PWK 38S.
Title: 38 PKW Airstrike Carb from JD jetting
Post by: Jeram on June 23, 2012, 04:39:28 AM
Quote from: scotty dog on June 22, 2012, 06:32:09 PM

Do you know what other mods can be done to the CR to get it really goin Jeram??

yeah, but none are easy OR cheap and depends completely on the style of riding.

I was after top end, so I build a 6 speed counterbalanced bottom end with a top end thats similar in spec to a national superkart