who's running a keihin PWK carb on their 250 2-stroke

[joe_f7]

looking for some starting points on jetting my 86 tecate with some porting, (don't know who did it), boysen stage 2 reeds in stock cage, stock airbox with filter, and fmf pipe and DG silencer. might be similar to other 250 strokes baseline

[Daddio]

What size pwk?

[joe_f7]

it is a 39mm PWK

[ChrisD]

Well it will depend on your pipe, temperature, sea level and compression in addition, but I can at least give you what I use.

For the summer, I use a 190 main and a 60 pilot jet on my 39PWKs. It has worked well on great on both of my R's with 250 and 270cc motors. I finally got my 330 jetted on the last day of this winter. That carb is a 40.5 A/S PWK. I use a 175 main and a 62 pilot. I also had to set the needle clip on the highest groove to smooth out a fat spot at mid range.

You will have to figure these things out. I would start fat and go leaner until it stops breaking up at top end. Then if you still get some sputter at mid range, I would adjust your clip position. I would start my clip position in the middle groove.

[joe_f7]

it's a fmf pipe with a dg silencer. i'll be riding very close to sea level in anywhere from 60-80 degree temps. just looking for a all around jet. another guy on a kawi forum said he was running a 170 in his KXF 300 big bore with a 55 pilot.

[3Razors]

Start out really fat on the the main jet like (190) and work your way down until it revs out clean. Then do a plug check for color.

[Bryan Raffa]

I got a 39 PWK with a #55 and a 160 main 50:1 ratio

[joe_f7]

Start out really fat on the the main jet like (190) and work your way down until it revs out clean. Then do a plug check for color.

really. go that fat?

[Bryan Raffa]

I would say start at 175..maybe even 180 they go down two sizes at a time

[joe_f7]

well i had a 42 pilot and a 160 main, and i was lean on the pilot and rich on the main. 1/2-3/4 throttle felt better that full. i was 3 turns out on the air screw and i put a 150 pilot in and am only 1 turn out now. i will be going to a 155 main to see how that does. i lowered the needle all the way when i had the 160 and it helped out a little. the top of the piston was almost completely washed clean too.

[cr480r]

In my 250 kawi I use a 40 and a 168 (still fat)with my 38pwk.. Do you still use an airbox? I would alter one circuit at a time.. I usually start with the pilot and airscrew.. then move to the needle in the middle and lean it out til it runs clean... then start tuning the main starting way fat... the only way to know if its rich IMO is to make it obviously rich.. and then creep down

[joe_f7]

yes, i'm running the stock air box. it's close, but too rich on top. piston wash wasn't right. it smokes alot too. the only thing i don't see is how everyone else is so rich on there main, but i suppose no one near my area has given any jetting that they've run. i'm also running the DG jets out of the 5 pack that they sell. so i don't know if that makes a difference.

[3Razors]

What needle are you running? Klemm Research recommended a DEF needle for the tecate and I found it ran awesome with that needle.

The DG packaged jets are good, they are genuine Keihin so no worries there.

My tecates use a 55 pilot

What fuel/oil ratio are you running?

[Daddio]

There are a lot of variables in jetting a 2stroke. I don't think most people ever get theirs totally dialed in because it is a very tedious task. It's safer to run a little on the rich side so a lot of people choose to run theirs like that.
My son drag races an air cooled 250r with a ported hondaline 300 kit on it. He is running vforce3 reeds and a 39 pwk carb with a uni pod filter, no airbox and a cobra pipe. He is running 110 octane with amsoil dominator racing oil at 20 to 1. The carb has the stock 50 pilot jet and a 152 main jet. The last time he had it out he decided that the main was still a little on the rich side and will try a 150 or smaller the next time out.
One thing to remember is decide what kind of fuel and oil you are going to use and the mixture you want to run and stick with that. Then get it jetted properly. 2strokes are very sensitive to change and even the slightest change in anything will throw off the jetting a little.

[joe_f7]

right on. i'm at a 42 pilot with the air screw out 2.5 turns, and it doesn't want to idle. i have a 158 main in right now with the clip in one down from the middle. it is 70 right now and it's running totally different than last weekend when it was warmer. my power valves were stuck open too. now those are working the thing has it's bottom end power back but it seems like i'm starting over on the jetting. seems to run good on the top end, but i need to get this pilot dialed in. i had a 50 pilot in and it was doing the same thing. i don't see a idle adjustment so i assume you do it with the pilot?

update: now with a 42 pilot and 4 turns out onthe screw it is starting to idle. looks like i may need a smaller pilot. maybe a 38 or 40?

[3Razors]

If its a pwk it has has both a idle screw for the slide and a air screw. Ideally you want your airscrew between 1 to 2 turns out, if not pilot jet needs to be changed.

Joe how did you like getting that stock airboot over a 39mm? A pain in the but!

[joe_f7]

ok. i think the screw for the slide is all the way in. i ended up boiling the air boot in water and stretching it over a lysol can for a couple of days. it helped a little, but yes it was a pain. not for carb adjusting i'm just removing the boot from the airbox and leaving the carb attached to it.