2001 CR250 carb sucks

[dogger315]

The new style uses a top retained by 2 screws

The version you are talking about is a Keihin PWK OE spec carb.
These use the PWK basic features like the semi D slide with the
air strykers, but the rest of the carb is heavily modified to suit
a particular application. Kawasaki, Suzuki, Yamaha and even
KTM all used this version that features a throttle position sensor,
electronic power valve and modified cap. This is a very trick
carb with a very trick price (retailing for almost half what bundyho1
paid for his bike). Honda was the loan user of the Mikuni TMX and
paid the price.

It was like Honda hired a bunch of idiots to ruin their two stroke
program - Case reeds, electronic power valves, "boat anchor"
crankshafts, Mikuni TMXs. The list is long and ridiculous.

You can get a similar version of this carb called the PWM which
is available without the electronics and would make a killer carb for
any 250.

dogger

[bundyho1]

Originally Posted by YZhallsme

bundyho1 do you know what bike your PWK came from? The PWK from the 00' is the old style which has a twist on top, shown here. [Only registered and activated users can see links. ]
The new style uses a top retained by 2 screws (similar to your TMX).
[Only registered and activated users can see links. ]

The newer style is reported to be shorter in distance from the inlet to the outlet than the older style. If I remember right the float settings between these 2 carbs is also different. Most of the newer style PWK's I've seen come with some type of electrical wiring (similar to what you see in the link). However KTM's been using a 36mm version of this newer style PWK carb without the electronics for several years now. As far as I know the jets, needles, and slides are interchangeable between the newer and older style PWK's.

FWIW I haven't had any trouble getting the TMX to idle. But I'm with you in thinking that it is jetted way too rich in stock form.

Its like the first one..from the 2000 model

---------- Post added at 05:44 PM ---------- Previous post was at 05:36 PM ----------

Originally Posted by dogger315

The version you are talking about is a Keihin PWK OE spec carb.
These use the PWK basic features like the semi D slide with the
air strykers, but the rest of the carb is heavily modified to suit
a particular application. Kawasaki, Suzuki, Yamaha and even
KTM all used this version that features a throttle position sensor,
electronic power valve and modified cap. This is a very trick
carb with a very trick price (retailing for almost half what bundyho1
paid for his bike). Honda was the loan user of the Mikuni TMX and
paid the price.

It was like Honda hired a bunch of idiots to ruin their two stroke
program - Case reeds, electronic power valves, "boat anchor"
crankshafts, Mikuni TMXs. The list is long and ridiculous.

You can get a similar version of this carb called the PWM which
is available without the electronics and would make a killer carb for
any 250.

dogger

Man that PWM carb sure do look pretty ,WOuldnt have a clue on jetting it though,also looked around there isnt much info on this carb,none on ebay just the pwk

[YZhallsme]

Originally Posted by dogger315

The version you are talking about is a Keihin PWK OE spec carb.
These use the PWK basic features like the semi D slide with the
air strykers, but the rest of the carb is heavily modified to suit
a particular application. Kawasaki, Suzuki, Yamaha and even
KTM all used this version that features a throttle position sensor,
electronic power valve and modified cap. This is a very trick
carb with a very trick price (retailing for almost half what bundyho1
paid for his bike). Honda was the loan user of the Mikuni TMX and
paid the price.

Aside from a power jet circuit thats controled by a solenoid, and a throttle position sensor what other mods do these carbs incorporate?

I think KTM's only use of a PWK power jet carb was on the 2000 SX. Heres a link to the PWK used on most of KTM's 2strokes today, no electronics.
http://65.57.254.60/shoponline/catal...85033111%2Egif
If you look around you'll find you can get a new 38mm version of this carb for @ $250.

You can get a similar version of this carb called the PWM which
is available without the electronics and would make a killer carb for
any 250.

dogger

I don't think the PWM has a seperate idle circuit like the PWK. It looks like you get the old combination choke/idle that was on the PJ. IMHO for the money, I think I'd rather have the old PWK airstriker and it's seperate idle screw. If I was spending $250 for a new carb it would be on the KTM PWK mentioned above.

bundyho1 I think it's a good thing that you have the older style PWK as I'm afraid you might have trouble trying to get a newer style to fit. It looks to me like the newer PWK is a good 13mm shorter than our CR Mikuni's.

[dogger315]

YZhallsme and bundyho1,

I don't want to beat this to death, but Just to clear up some misconceptions,
I submit the following:

Here is a picture from the Keihin website of the PWK quad vent air striker.


It has a screw-on cap, is 91mm from front to back and has a modified
D slide with bat wings.

The carburetor shown in the exploded parts diagram you listed IS a PWK
by virtue of the slide design and the separate idle circuit. But it is also a
"boutique" (specially made to a manufacturer's specifications) carburetor.
The carb body, cap, dimensions and electronics are all unique to that
version for that application.

There are no early or late model PWKs. If you ordered the latest model
of PWK from Keihin or Sudco, you would get a carb that looks just like
the one in the picture. Any other PWK is a specialty version
manufactured by Keihin to an OEs specifications.

The newer style is reported to be shorter in distance from the inlet to the outlet than the older style

The distance from the inlet bell to the spigot directly affects the position
of the powerband. For instance, a 91 mm PWK will have better low to mid
than a 75mm PWM which will be more mid and up. Unless you know what
you are doing, I wouldn't recommend altering any of your carb dimensions.
Just replace like with like, size wise

IMHO for the money, I think I'd rather have the old PWK airstriker and it's seperate idle screw.

Agreed. The PWM is Keihins latest and greatest, but I also like the convenience of a separate idle screw.

bundyho1 I think it's a good thing that you have the older style PWK as I'm afraid you might have trouble trying to get a newer style to fit. It looks to me like the newer PWK is a good 13mm shorter than our CR Mikuni's.

The Mikuni TMX is 76mm from spigot to bell, basically the same as a PWM.
The PWK on the other hand, is 15 mm longer than the TMX, which is why
many comment on the difficulty of stuffing a PWK into their TMX equipped
bikes. On the plus side, the PJ that the steel framed CRs came with is 91mm
from spigot to bell just like the PWK. Which means I will have no trouble
substituting a "striker" for the PJ on my '93 resto.

dogger

[bundyho1]

really good info,i will update when i get the pwk carb installed.

[YZhallsme]

dogger315 I think it's important that those reading this or considering a change to a PWK carb understand that there are variations of the PWK carb. Yes there are PWK's that are made for the O.E.M.'s and they are made to the manufacturers specs, they can and do differ from the aftermarket versions offered from Keihin, those differences can be minor (00' cr 250) or huge (03' YZ 250). My guess is that most (not all), will look to E-bay or a similar source for a used carb and there they can find any of the variations produced to date, most likely though all will be refered to as simply "a 38mm PWK". Even today the aftermarket PWK offered from Keihin appears to be available in 2 variations. The standard 38mm PWK = part# 71R, and the Quadvents/Airstriker 38mm PWK = part# S66. [Only registered and activated users can see links. ]

bundyho1 I'm still unclear as to which version of the PWK your getting, I understand it's an airstriker but is it the aftermarket S66 or one from an O.E.M.? At any rate I wish you well and look forward to hearing how it works out.

[bundyho1]

here is the one i got ebay Item number: 320385691952
i had a coupon and didnt pay that much

man i hope its not too hard to fit in there.

---------- Post added at 09:57 PM ---------- Previous post was at 09:46 PM ----------

Originally Posted by dogger315

YZhallsme and bundyho1,

I don't want to beat this to death, but Just to clear up some misconceptions,
I submit the following:

Here is a picture from the Keihin website of the PWK quad vent air striker.


It has a screw-on cap, is 91mm from front to back and has a modified
D slide with bat wings.

The carburetor shown in the exploded parts diagram you listed IS a PWK
by virtue of the slide design and the separate idle circuit. But it is also a
"boutique" (specially made to a manufacturer's specifications) carburetor.
The carb body, cap, dimensions and electronics are all unique to that
version for that application.

There are no early or late model PWKs. If you ordered the latest model
of PWK from Keihin or Sudco, you would get a carb that looks just like
the one in the picture. Any other PWK is a specialty version
manufactured by Keihin to an OEs specifications.


The distance from the inlet bell to the spigot directly affects the position
of the powerband. For instance, a 91 mm PWK will have better low to mid
than a 75mm PWM which will be more mid and up. Unless you know what
you are doing, I wouldn't recommend altering any of your carb dimensions.
Just replace like with like, size wise


Agreed. The PWM is Keihins latest and greatest, but I also like the convenience of a separate idle screw.



The Mikuni TMX is 76mm from spigot to bell, basically the same as a PWM.
The PWK on the other hand, is 15 mm longer than the TMX, which is why
many comment on the difficulty of stuffing a PWK into their TMX equipped
bikes. On the plus side, the PJ that the steel framed CRs came with is 91mm
from spigot to bell just like the PWK. Which means I will have no trouble
substituting a "striker" for the PJ on my '93 resto.

dogger

So dogger are you saying that with this switch i will loose some topend?I dont think i like the sound of that.Also would a 2000 model intake boot help?So dogger what would you do keep the TMX or go with the PWK?Again thanks alot for this info dogger.

[dogger315]

dogger315 I think it's important that those reading this or considering a change to a PWK carb understand that there are variations of the PWK carb. Yes there are PWK's that are made for the O.E.M.'s and they are made to the manufacturers specs, they can and do differ from the aftermarket versions offered from Keihin, those differences can be minor (00' cr 250) or huge (03' YZ 250). My guess is that most (not all), will look to E-bay or a similar source for a used carb and there they can find any of the variations produced to date, most likely though all will be refered to as simply "a 38mm PWK". Even today the aftermarket PWK offered from Keihin appears to be available in 2 variations. The standard 38mm PWK = part# 71R, and the Quadvents/Airstriker 38mm PWK = part# S66.

Excellent points and I agree with all of them. You and I are on the same
page here.

are you saying that with this switch i will loose some topend?

You will loose a little overrev, but gain a little punch at low to mid which
is where you spend most of your time. Unless you are an A class (expert
or pro) you won't even notice, much less miss the change.

would a 2000 model intake boot help?

Good idea, the 2000 intake/airbox distance is identical to the 2001,
so substituting a '00 carb insulator for an '01 would compensate for
the additional carb depth. The Honda part number for the insulator
you need is 16221-KZ3-J20. The reed valve is the same for both years.
We're only talking 3/4" here, but the fit is tight already so this change
would definitely make life easier.

keep the TMX or go with the PWK?

Personally, I would go with the PWK. You already bought one. The PWK
is less tempermental and I think it will be beneficial in that it will allow you
to ride and have fun on your CR instead of constantly screwing with the
jetting as the temperature and humidity change. By the way, I was wrong,
you don't have to change the throttle cable.

dogger

[bundyho1]

OK i priced the carb insulator and its 50+$.Im wondering what do you all think of the boyesen rad valve.I have seen them for 129$.I might as well get reeds for it too i guess.THey are the stock ones in there.I wonder how well they work with the cr250 ?

[dogger315]

I still recommend the VForce over the Boyesen. I have used both and
both are an improvement over stock, but the VForce is superior to the
Boyesen.

The one on Ebay is 5% off for a total of $114 and free shipping from
Trinity Racing. Got mine two days after I bought it. Here is the Ebay
item number: 260398261088 By the way, the 5% off ends tomorrow.

Better Reed for less money, sounds like an easy choice.

dogger

[bundyho1]

hey dogger do i need to buy the clamp that goes with the INSULATOR, or does the 2001 one work?Just want to know before i get one soon..

[dogger315]

No problem using your OE clamp.

Here is a picture of my new-in-the-bag Keihin PWK quad vent
air striker. Pre-jetted, float level already set and ready to bolt
on for $168 from Honda. I can't believe what a good deal it is!
You can't buy a lousy PJ for under $200 from Honda. I am going
to buy a few more to have for spares and use on other projects
at this price.

By the way, I did a little research and found out the only CR that
came with this carburetor was the 2000 250. Prior years came
with non air striker PWKs or PJs and subsequent years came
equipped with the TMX.

dogger

[bundyho1]

yea that is a great deal.Im wondering what Pre-jetted settings is on the carb?the 2000 model jetting?Well i went ahead and got those reeds(v-force).Now do i have to cut the 00 carb insulator when it gets here to fit the reeds in?Thanks

[YZhallsme]

Originally Posted by bundyho1

yea that is a great deal.Im wondering what Pre-jetted settings is on the carb?the 2000 model jetting?

bundyho1 the stock 00' comes with a 180 main, 48 pilot jet, needle# A715/289R/A327/A487 clip position #3, airscrew 1.5 turns out, float level 16mm.

Dogger I've been told the 99' carb was a PWK airstriker also but don't know for sure!

The 00' needles are triple taper needles. The first 3 numbers in the needle number relates to the needles straight diameter, the stock A715 then = 2.715mm. They are available in .10mm increments from 2.685 thru 2.745. In the parts fiche they show another set of needles with the same diameters but the second set of 3 digitis is 294R instead of 289R. I think these needles are the same except for a 1/2 clip position. Don't know if they are richer or leaner, they aren't mentioned in the service manual.

[dogger315]

I've been told the 99' carb was a PWK airstriker also but don't know for sure

I thought the same thing. While I was researching this, I took a look at the
exploded parts diagram for both carburetors. If you look at the slide in the
first diagram, you'll notice it is a straight up D-slide with no "bat wings".
This indicates the carburetor is a non air striker PWK. It is also listed as a
PWK00A A in the parts description which corresponds to a normal PWK quad
vent.

Now look at the slide in the '00 carb diagram. The "bat wings" are present
so this carb is an air striker PWK.

Honda used a PJ28LA with throttle position sensor and power jet in 97 and
98, which was a bust. Then switched to Mikuni and the TMX in '02 and
stuck with that until CR production stopped, leaving '00 as the only year
the Air Striker made an appearance on the CR.

dogger

[YZhallsme]

Originally Posted by dogger315

I thought the same thing. While I was researching this, I took a look at the
exploded parts diagram for both carburetors. If you look at the slide in the
first diagram, you'll notice it is a straight up D-slide with no "bat wings".
This indicates the carburetor is a non air striker PWK. It is also listed as a
PWK00A A in the parts description which corresponds to a normal PWK quad
vent.Now look at the slide in the '00 carb diagram. The "bat wings" are present
so this carb is an air striker PWK.

From my research the 99' diagram is reported to be incorrect. Actually the slide shown in that diagram is a PJ slide. I think you may be confused on the difference between a PWK and a PWK airstriker. It is the vanes in the bottom of the carb that make it the airstriker version (not the slide), the slides are all the same. Look at the carbs in this link [Only registered and activated users can see links. ] the one on the left is a PWK, on the right is the PWK airstriker. So to me there are 3 versions of this carb. And my guess is they showed up or were developed in the following order.
1=standard PWK (no vanes), available from Keihin and the O.E.M.'s
2= PWK Air striker (vanes), available from Keihin and the O.E.M.'s
3= PWK Air striker with shortened body (my 03' measures 75mm), available from the O.E.M.'s. Used on YZ, KX and RM 250's since @ 00' and by KTM since @ 04'.

Honda used a PJ28LA with throttle position sensor and power jet in 97 and
98, which was a bust. Then switched to Mikuni and the TMX in '02 and
stuck with that until CR production stopped, leaving '00 as the only year
the Air Striker made an appearance on the CR.

To me the TMX is a mystery, apparently it came in several variations also, with at least 3 different slide configurations. A-The one I always see when looking up Mikuni TMX. Looks similar to what you call D shape with bat wings [Only registered and activated users can see links. ]

B-The square or match box shaped one used on the 01' to 03' CR 250 [Only registered and activated users can see links. ]

And C the curved one used on the 04' to 07' CR 250 [Only registered and activated users can see links. ].

[dogger315]

Thanks for the "schooling". I see the vanes cast into the inlet bell.
Learn something everyday.

I went back and looked at some additional resources after reading your
post and finally found one that included a description of the '99 carb.
According to this source the '99 carb is the same as the '00 carb, both
are PWK 38 quad vent air strikers. You are absolutely right and I stand
corrected.

I really appreciate this "refresher" on carburetor identification. Cleared
up some misconceptions and I picked up some useful information - what
more could you ask for.

dogger

[bundyho1]

Ok i have most of my parts in and will be installing and testing it out the next few days.I have been doing alot of reading on this and i have the stock 99 jet needle and the ddk one to play with.Im at about 900ft above sea level and from what i have read im going to start out with a 178 main and a 42 pilot.needle clip in the 2nd p. weather now is in the 80s.So what do you guys think?

[YZhallsme]

Originally Posted by dogger315

Thanks for the "schooling". I see the vanes cast into the inlet bell.
Learn something everyday.

I went back and looked at some additional resources after reading your
post and finally found one that included a description of the '99 carb.
According to this source the '99 carb is the same as the '00 carb, both
are PWK 38 quad vent air strikers. You are absolutely right and I stand
corrected.

I really appreciate this "refresher" on carburetor identification. Cleared
up some misconceptions and I picked up some useful information - what
more could you ask for.

dogger

Dogger your welcome. Now I'm hoping you can educate me. I've seen you post the carb ID #'s a few times. I was wondering if there is a place I can go (other than the manual) to find these identification #'s? For those that may be interested the identification # stamped in the 00' CR 250 carb is PWK00B. I'm wondering if the 99' CR 250 carb ID # is PWK00A??

---------- Post added at 08:23 PM ---------- Previous post was at 06:53 PM ----------

Originally Posted by bundyho1

Ok i have most of my parts in and will be installing and testing it out the next few days.

Could you clarify which parts you ended up with? V-force III or V-force Delta II, and wether or not you had to cut the insulator (stuffers) off? Also if you get a chance can you measure the overall length (inlet to outlet) of your stock Mikuni TMX?

I have been doing alot of reading on this and i have the stock 99 jet needle and the ddk one to play with.Im at about 900ft above sea level and from what i have read im going to start out with a 178 main and a 42 pilot.needle clip in the 2nd p. weather now is in the 80s.So what do you guys think?

Sorry but I haven't made the switch from the TMX to PWK so I have no clue. It might be best to use the info. from those that have. One thing you might want to make note of and/or post, is your throttle valve (slide) number. Keihin makes them with several different cutaways. [Only registered and activated users can see links. ]
The cutaway will have an effect early in the throttle range. See the graph and #7 [Only registered and activated users can see links. ]

Over the last two years I've read many many threads about this. I can't recall anyone (zero, zippo, nada) ever going back to the Mikuni!

[dogger315]

I'm wondering if the 99' CR 250 carb ID # is PWK00A??

Right on the money.

was wondering if there is a place I can go (other than the manual) to find these identification #'s?

Go to this website: [Only registered and activated users can see links. ]
Navigate to the specific model you are interested in, and scroll down to
the section marked serial numbers. The site contains lots of useful
information and is a "goldmine" for rare vintage parts - for a price.

dogger