Help : Keihin PWK 38 Air Striker on 1991 CR 250 R

Maxx MRP
Posts
207
Joined
11/18/2015
Location
FR
Hello everyone
I have my 1991 Honda 250 CR that you may have seen in the "bike of the day's" which has a problem with the original carburetor, there is a problem between the needle well and the carburetor body and I can't disassemble, it's on the original PJ 38, so I couldn't get the carburetion properly adjusted.
So I ordered a PWK 38 Air Striker, I will receive it in about 3 weeks, I would like to know if any of you have done this assembly on the same bike or the same engine, to be able to give me (even if I'm in France and the gasoline is not identical) the main jet settings, idle jet, needle model, position of the needle clips, air screw etc...

I thank you for your invaluable help, in order to allow me to leave already on a good basis, because I think that it will arrive with adjustments which will not be compatible with the motorcycle.
Thank you all
take care of yourself
Cordially
Max
|
digger
Posts
800
Joined
4/1/2008
Location
Upstate, NY, USA
4/23/2022 8:07am Edited Date/Time 9/8/2022 6:57pm
Maxx MRP wrote:
Hello everyone I have my 1991 Honda 250 CR that you may have seen in the "bike of the day's" which has a problem with the...
Hello everyone
I have my 1991 Honda 250 CR that you may have seen in the "bike of the day's" which has a problem with the original carburetor, there is a problem between the needle well and the carburetor body and I can't disassemble, it's on the original PJ 38, so I couldn't get the carburetion properly adjusted.
So I ordered a PWK 38 Air Striker, I will receive it in about 3 weeks, I would like to know if any of you have done this assembly on the same bike or the same engine, to be able to give me (even if I'm in France and the gasoline is not identical) the main jet settings, idle jet, needle model, position of the needle clips, air screw etc...

I thank you for your invaluable help, in order to allow me to leave already on a good basis, because I think that it will arrive with adjustments which will not be compatible with the motorcycle.
Thank you all
take care of yourself
Cordially
Max
It’s a pretty smart move on your part to replace the PJ with a newer PWK. This is a common mod and will work very on your engine.
I’m going to assume you are using the bike for general offroad use, and that the carb you are buying has a #7 slide.
I recommend:
Needle—Suzuki NECH in the #3 clip position
Pilot—42
Main—172
Air screw 1.5 turns out from being fully closed
Slide—#7– assuming the carb come with it.
Float—make sure it’s at 16mm. This is for the screw top PWK
If you would like a harder hit into the middle, I have different specs for that.
4
Maxx MRP
Posts
207
Joined
11/18/2015
Location
FR
4/29/2022 8:48am
Maxx MRP wrote:
Hello everyone I have my 1991 Honda 250 CR that you may have seen in the "bike of the day's" which has a problem with the...
Hello everyone
I have my 1991 Honda 250 CR that you may have seen in the "bike of the day's" which has a problem with the original carburetor, there is a problem between the needle well and the carburetor body and I can't disassemble, it's on the original PJ 38, so I couldn't get the carburetion properly adjusted.
So I ordered a PWK 38 Air Striker, I will receive it in about 3 weeks, I would like to know if any of you have done this assembly on the same bike or the same engine, to be able to give me (even if I'm in France and the gasoline is not identical) the main jet settings, idle jet, needle model, position of the needle clips, air screw etc...

I thank you for your invaluable help, in order to allow me to leave already on a good basis, because I think that it will arrive with adjustments which will not be compatible with the motorcycle.
Thank you all
take care of yourself
Cordially
Max
digger wrote:
It’s a pretty smart move on your part to replace the PJ with a newer PWK. This is a common mod and will work very on...
It’s a pretty smart move on your part to replace the PJ with a newer PWK. This is a common mod and will work very on your engine.
I’m going to assume you are using the bike for general offroad use, and that the carb you are buying has a #7 slide.
I recommend:
Needle—Suzuki NECH in the #3 clip position
Pilot—42
Main—172
Air screw 1.5 turns out from being fully closed
Slide—#7– assuming the carb come with it.
Float—make sure it’s at 16mm. This is for the screw top PWK
If you would like a harder hit into the middle, I have different specs for that.
Thanks for your answer
Best regards
Maxx
5/2/2022 6:00am
Maxx MRP wrote:
Hello everyone I have my 1991 Honda 250 CR that you may have seen in the "bike of the day's" which has a problem with the...
Hello everyone
I have my 1991 Honda 250 CR that you may have seen in the "bike of the day's" which has a problem with the original carburetor, there is a problem between the needle well and the carburetor body and I can't disassemble, it's on the original PJ 38, so I couldn't get the carburetion properly adjusted.
So I ordered a PWK 38 Air Striker, I will receive it in about 3 weeks, I would like to know if any of you have done this assembly on the same bike or the same engine, to be able to give me (even if I'm in France and the gasoline is not identical) the main jet settings, idle jet, needle model, position of the needle clips, air screw etc...

I thank you for your invaluable help, in order to allow me to leave already on a good basis, because I think that it will arrive with adjustments which will not be compatible with the motorcycle.
Thank you all
take care of yourself
Cordially
Max
digger wrote:
It’s a pretty smart move on your part to replace the PJ with a newer PWK. This is a common mod and will work very on...
It’s a pretty smart move on your part to replace the PJ with a newer PWK. This is a common mod and will work very on your engine.
I’m going to assume you are using the bike for general offroad use, and that the carb you are buying has a #7 slide.
I recommend:
Needle—Suzuki NECH in the #3 clip position
Pilot—42
Main—172
Air screw 1.5 turns out from being fully closed
Slide—#7– assuming the carb come with it.
Float—make sure it’s at 16mm. This is for the screw top PWK
If you would like a harder hit into the middle, I have different specs for that.
That's very close to the settings on my PWK 38 for my 79 YZ400.

Needle-- DDJ Second from bottom clip
Pilot-- 42
Main-- 170
Air screw-- 1.75 turns out from being fully closed
Slide-- #7
Float-- set at 14mm-- 2mm below stock setting

Runs great with these settings.
Alex814
Posts
1257
Joined
12/18/2014
Location
USA
5/18/2022 10:02pm Edited Date/Time 5/19/2022 11:18am
Maxx MRP wrote:
Hello everyone I have my 1991 Honda 250 CR that you may have seen in the "bike of the day's" which has a problem with the...
Hello everyone
I have my 1991 Honda 250 CR that you may have seen in the "bike of the day's" which has a problem with the original carburetor, there is a problem between the needle well and the carburetor body and I can't disassemble, it's on the original PJ 38, so I couldn't get the carburetion properly adjusted.
So I ordered a PWK 38 Air Striker, I will receive it in about 3 weeks, I would like to know if any of you have done this assembly on the same bike or the same engine, to be able to give me (even if I'm in France and the gasoline is not identical) the main jet settings, idle jet, needle model, position of the needle clips, air screw etc...

I thank you for your invaluable help, in order to allow me to leave already on a good basis, because I think that it will arrive with adjustments which will not be compatible with the motorcycle.
Thank you all
take care of yourself
Cordially
Max
digger wrote:
It’s a pretty smart move on your part to replace the PJ with a newer PWK. This is a common mod and will work very on...
It’s a pretty smart move on your part to replace the PJ with a newer PWK. This is a common mod and will work very on your engine.
I’m going to assume you are using the bike for general offroad use, and that the carb you are buying has a #7 slide.
I recommend:
Needle—Suzuki NECH in the #3 clip position
Pilot—42
Main—172
Air screw 1.5 turns out from being fully closed
Slide—#7– assuming the carb come with it.
Float—make sure it’s at 16mm. This is for the screw top PWK
If you would like a harder hit into the middle, I have different specs for that.
Op - Did you install the PWK on your '91 yet?

I'm having issues getting an '89 CR250 running that I just put a PWK 38 on. Also has a new top end. I bought the carb through JD jetting with the jet kit and am using their recommended settings, below.

It fired when cold a couple of times but would die very quickly without applying constant throttle.
A day later I tried going to 3 turns out on the air screw and it doesn't start at all.

Should I try a different float level? Stock is 16mm and the PWK also came set at 16mm. I didn't note the slide # in the carb before assembling. UPDATE: I have the #7 slide and the JD red and blue needles have no markings. Also have a DDJ needle that came with carb.

Fuel VPR 32:1 Honda HP2
Needle JD Blue #3 clip position
Pilot 45
Main 175
Air screw 2 turns out
Float 16mm
Slide #7


Could these settings really be too rich for the bike to even start ? I tested compression at 145psi, but the engine and gaskets haven't seen a heat cycle yet.
1

The Shop

digger
Posts
800
Joined
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Location
Upstate, NY, USA
5/20/2022 9:04am
Alex814 wrote:
Op - Did you install the PWK on your '91 yet? I'm having issues getting an '89 CR250 running that I just put a PWK 38...
Op - Did you install the PWK on your '91 yet?

I'm having issues getting an '89 CR250 running that I just put a PWK 38 on. Also has a new top end. I bought the carb through JD jetting with the jet kit and am using their recommended settings, below.

It fired when cold a couple of times but would die very quickly without applying constant throttle.
A day later I tried going to 3 turns out on the air screw and it doesn't start at all.

Should I try a different float level? Stock is 16mm and the PWK also came set at 16mm. I didn't note the slide # in the carb before assembling. UPDATE: I have the #7 slide and the JD red and blue needles have no markings. Also have a DDJ needle that came with carb.

Fuel VPR 32:1 Honda HP2
Needle JD Blue #3 clip position
Pilot 45
Main 175
Air screw 2 turns out
Float 16mm
Slide #7


Could these settings really be too rich for the bike to even start ? I tested compression at 145psi, but the engine and gaskets haven't seen a heat cycle yet.
Those setting may very well be a little on the rich/safe side, but they seem very well within the spectrum of getting the bike to start and run, while giving you a platform to tune from.
1
Alex814
Posts
1257
Joined
12/18/2014
Location
USA
5/22/2022 7:27pm
Alex814 wrote:
Op - Did you install the PWK on your '91 yet? I'm having issues getting an '89 CR250 running that I just put a PWK 38...
Op - Did you install the PWK on your '91 yet?

I'm having issues getting an '89 CR250 running that I just put a PWK 38 on. Also has a new top end. I bought the carb through JD jetting with the jet kit and am using their recommended settings, below.

It fired when cold a couple of times but would die very quickly without applying constant throttle.
A day later I tried going to 3 turns out on the air screw and it doesn't start at all.

Should I try a different float level? Stock is 16mm and the PWK also came set at 16mm. I didn't note the slide # in the carb before assembling. UPDATE: I have the #7 slide and the JD red and blue needles have no markings. Also have a DDJ needle that came with carb.

Fuel VPR 32:1 Honda HP2
Needle JD Blue #3 clip position
Pilot 45
Main 175
Air screw 2 turns out
Float 16mm
Slide #7


Could these settings really be too rich for the bike to even start ? I tested compression at 145psi, but the engine and gaskets haven't seen a heat cycle yet.
digger wrote:
Those setting may very well be a little on the rich/safe side, but they seem very well within the spectrum of getting the bike to start...
Those setting may very well be a little on the rich/safe side, but they seem very well within the spectrum of getting the bike to start and run, while giving you a platform to tune from.
I swapped the blue JD needle out for the red and got it running and idling, now to monitor the small coolant leak coming through the head bolts...
Maxx MRP
Posts
207
Joined
11/18/2015
Location
FR
9/8/2022 2:54pm
Maxx MRP wrote:
Hello everyone I have my 1991 Honda 250 CR that you may have seen in the "bike of the day's" which has a problem with the...
Hello everyone
I have my 1991 Honda 250 CR that you may have seen in the "bike of the day's" which has a problem with the original carburetor, there is a problem between the needle well and the carburetor body and I can't disassemble, it's on the original PJ 38, so I couldn't get the carburetion properly adjusted.
So I ordered a PWK 38 Air Striker, I will receive it in about 3 weeks, I would like to know if any of you have done this assembly on the same bike or the same engine, to be able to give me (even if I'm in France and the gasoline is not identical) the main jet settings, idle jet, needle model, position of the needle clips, air screw etc...

I thank you for your invaluable help, in order to allow me to leave already on a good basis, because I think that it will arrive with adjustments which will not be compatible with the motorcycle.
Thank you all
take care of yourself
Cordially
Max
digger wrote:
It’s a pretty smart move on your part to replace the PJ with a newer PWK. This is a common mod and will work very on...
It’s a pretty smart move on your part to replace the PJ with a newer PWK. This is a common mod and will work very on your engine.
I’m going to assume you are using the bike for general offroad use, and that the carb you are buying has a #7 slide.
I recommend:
Needle—Suzuki NECH in the #3 clip position
Pilot—42
Main—172
Air screw 1.5 turns out from being fully closed
Slide—#7– assuming the carb come with it.
Float—make sure it’s at 16mm. This is for the screw top PWK
If you would like a harder hit into the middle, I have different specs for that.
Alex814 wrote:
Op - Did you install the PWK on your '91 yet? I'm having issues getting an '89 CR250 running that I just put a PWK 38...
Op - Did you install the PWK on your '91 yet?

I'm having issues getting an '89 CR250 running that I just put a PWK 38 on. Also has a new top end. I bought the carb through JD jetting with the jet kit and am using their recommended settings, below.

It fired when cold a couple of times but would die very quickly without applying constant throttle.
A day later I tried going to 3 turns out on the air screw and it doesn't start at all.

Should I try a different float level? Stock is 16mm and the PWK also came set at 16mm. I didn't note the slide # in the carb before assembling. UPDATE: I have the #7 slide and the JD red and blue needles have no markings. Also have a DDJ needle that came with carb.

Fuel VPR 32:1 Honda HP2
Needle JD Blue #3 clip position
Pilot 45
Main 175
Air screw 2 turns out
Float 16mm
Slide #7


Could these settings really be too rich for the bike to even start ? I tested compression at 145psi, but the engine and gaskets haven't seen a heat cycle yet.
I have not yet installed the carburettor because I have just received it, it was out of stock since April at my supplier.
so I haven't been able to ride the bike since my 1st message, as soon as I have time in front of me, I mount the carburettor with the settings given by Digger
Maxx MRP
Posts
207
Joined
11/18/2015
Location
FR
10/17/2022 7:52am
Hi buddies
It's been a while since I've been here, the bike had carburettor issues, so I've been ordering a Keihin PWK 38 Air Striker since April and still haven't received, I've received a late September and it wasn't an Air Striker, so I sent it back and while waiting for the right one to arrive, or unless I'm falling for a Lectron or a Smartcarb, but bringing this to France from the USA costs a lot expensive in customs fees.
So in the meantime I bought a copy of PWK 38 Air Striker and I mounted everything in Keihin inside, jets, float etc..
I haven't ridden the bike since April 3, 2022 and this Saturday I went to test the bike on a field 60km from my home, a track that I didn't know, hard hard the dust, the heat, the holes and the stones, but I have the banana, the bike is not like before, now it works, I think maybe refine the carburation a bit more and we'll be ok, I'll do it on the track of my club or you have seen the other videos, if you had not seen them they are in the playlist of this video.
Thank you, my MX brothers.

1
Maxx MRP
Posts
207
Joined
11/18/2015
Location
FR
11/17/2022 4:40pm
I changed the carburettor, it worked well, I still enriched the mixture because of suspicious broken engine noises and this Sunday we went to drive in Italy and the engine broke.
piston cylinder blockage

I will enrich again, I was to pass to the adjustment of the original carburettor, with larger glcleurs than those given here above.
And I'm thinking of putting more oil in my premix, I always run at 2% I'm going to go to 3%.
I use the BelRay H1-R




captmoto
Posts
5909
Joined
4/22/2009
Location
Rancho Cucamonga, CA, USA
11/20/2022 9:03pm
That's very close to the settings on my PWK 38 for my 79 YZ400. Needle-- DDJ Second from bottom clip Pilot-- 42 Main-- 170 Air screw--...
That's very close to the settings on my PWK 38 for my 79 YZ400.

Needle-- DDJ Second from bottom clip
Pilot-- 42
Main-- 170
Air screw-- 1.75 turns out from being fully closed
Slide-- #7
Float-- set at 14mm-- 2mm below stock setting

Runs great with these settings.
I have this carb on a YZ465. I haven't spent much time with it since the first ride but it was real flat on top under a load. Abrupt off the bottom. My jetting is very similar to yours. I haven't messed with 2 stroke jetting in a while. Any suggestions on which way to go with this?
11/21/2022 5:46am
Have you tried a wide open spark plug chop test? If not, I suggest trying that first.
1

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