Attn: 2002/2003 CR250 Keihin PWK Converts

Faded

~SPONSOR~
Jan 7, 2003
842
0
Okay, after doing a few searches I've noticed that there are a handfull of you out there that took the plunge and coughed up the money for the PWK. There are a few things I'd like to know and I think this could end up being a benificial thread for future DRN posterity.

I don't need to ask why anyone made the switch, but I'd sure like to get some feedback from those that have. Here are a few questions I have...

  • How is it working?
  • How does it fit (still easy to change jets)?
  • Are you happy/would you do it again?
  • Any performance gain?
  • Any quirks?
  • Any thing else you'd like to add...

If you don't mind please list your current settings, temps, and elevation. Also, if it's not too personal where you purchased your carb and what it set you back. I am considering this option and I know there are probably others that are to, so I'm just trying to get some of the info out into the open.

Thanks in advance,
Andrew
:thumb:
 

Faded

~SPONSOR~
Jan 7, 2003
842
0
James,

What is holding you back? No time, desire....need? It seems as if the Keihin is everyone's cure-all to the CR jetting plague. I don't know that I'm ready to make the switch just yet, but I am curious to the truth behind the matter. Basically I will have the opportunity to 'test' a Keihin on my bike (courtesy of one generous chap) and I'm looking for help/guidance on where to start...what jetting did you order your Keihin with?
 

James

Lifetime Sponsor
LIFETIME SPONSOR
Dec 26, 2001
1,839
0
Most times, my Mikuni works fine...so I haven't really felt the need yet BUT I still ride the 2000 a MAJORITY of the time. Rode the 02 two weeks ago and installed my fall jetting (30, 380, 2nd notch from bottom, S9 nozzle) back in before I left the house and it ran incredibly strong. I tried the S8 nozzle and I think it was too lean for all but the hottest and most humid days in the summer. I didn't go into this earlier because I didn't want the thread to turn into a theory debate....as I too would like to hear from those that actually did switch to the Keihin in the 02/03.

The Keihin I have came on the 2000 CR and I run 45/178/middle clip in it. Temps have been in the 70s, elevation of about 700ft. All of my bikes are stock so I know you'd have to adjust from there with the 265 and other mods...but stock 2000 CR jetting is 48/180/middle and that might not be a bad starting place if you can try the carb for free.

Just from looking at them....I'd say the fit should be fine and you should be able to get to the jets BUT the Keihin has 4 screws holding the float bowl on and is a bit harder to get apart. I bet that would be even worse with the Keihin on the 02 because the carb is very close to the cases on that bike.

I know there was a thread a while back where Motometal or one of the other CR250 guys put in a Keihin carb and liked it. I can't remember if it was an 01,02, or 03 though.
 
Last edited:

Faded

~SPONSOR~
Jan 7, 2003
842
0
James,

Thanks for the observations, I appreciate them. Any idea on what the needle # and slide # are for your Keihin? I'm not trying to be anal, but the Keihin I'll be using is coming off of a different bike.

Thank you,
Andrew
 

James

Lifetime Sponsor
LIFETIME SPONSOR
Dec 26, 2001
1,839
0
I understand. I'll have to look into the Slide and needle when I get home. I also promised somebody stock suspension clicker settings too so I better get busy tonite.

I just got through reading Bruce's thread on the PWK. I am glad mine seem to run well for me because you guys have a whole lot more patience than I do. I noticed that you ordered the 3.5 Mikuni slide which reminds me that I was supposed to try the 4.0 slide from the 01 in the 02 as I have heard about some guys doing this with good results.
 

Faded

~SPONSOR~
Jan 7, 2003
842
0
James,

Thanks, I appreciate you checking. From what I can gather the bike's stock jetting is good for near sea level. Throw some elevation into the mix and things start to get a little challenging. I've noticed that those bikes that I've kept tabs on all share almost the same problems and that is they're rich everywhere except a lean spot at just off idle to 1/4 throttle. Even modified mine exhibits the same traits, only worse. Stock this problem is masked by the stock pilot size, which was rich for me (and you too I noticed), and the overlap takes care of the lean spot but makes for slow revving off idle. So you drop the pilot, raise the clip (or worse, buy a leaner needle), swap in an S-8 and lower the main and all the sudden you have a hesitation at just off idle (or like mine which pings). If this is the case then a richer needle will do, problem is I'm at Honda's richest needle, 30-71...I called to order the 30-70 and, ummm they don't make that one. Now I'll be trying a richer slide with one of my needles to see if I can't make it work.

If this sounds like what you might be experiencing then the 4.0 slide will probably help you out. Of course being 4000ft closer to see level than I am might be enough that you don't have this problem... :confused:
 
Last edited:

Faded

~SPONSOR~
Jan 7, 2003
842
0
On a side note....if you'll notice for the '03s they came stock with a leaner pilot (30), richer slide (4.0) and a richer needle (38-73, meaning a straight section of 2.73mm), :think: :think: :think: which in theory should rev good off-idle and and remedy the lean spot at 1/4 throttle.
 

bclapham

LIFETIME SPONSOR
Nov 5, 2001
4,340
0
LOL: andrew, the carb i have will be coming with the stock 2000 cr250 needle and a #5 slide- since its the 39.5mm shell, this should bring you out in the same ball park as the stock #7 cr250 slide.

when i spoke to AJ at service honda, he said they were chucking the mikunis from their new cr250's- i suppose if you are going to try it, it might even be worth buying a pre-jetted carby straight from them; like i said, you are more than wellcome to try this spare carb, its all about how much time you have. send AJ an email and see what he says, their prices are more than reasonable, especially if you have to go out and buy a hundred new jets and needles. Not trying to put you off, its just that i know how annoying it is pi$$ing away hours working on these carbs when i should be flying around the track!
 

Faded

~SPONSOR~
Jan 7, 2003
842
0
Bruce,

Not to worry, I know you're not putting me off. :confused: Anyway, I blew yet another $20-ish and ordered that slide which should bring me back into the ballpark at 1/4 and (hopefully) let one of my five needles fine tune it. If this works I feel that my other circuits are close enough that I'll have it made with some ultra-fine tuning. Just for comparisons sake I'd still like to take the Keihin for a spin, I'm just trying to gather information to help me guesstimate where I'll need to be with that carb. Ultimately if the Mikuni doesn't work with my latest attempts I will refocus on jetting with the Keihin. That way I can get the Keihin figured out and order it with the jets I need. Remeber, my bike isn't your standard issue CR250...and I hate to say it but Santa may bring more variables to the party. :scream: If the offer still stands then I'm all over it. Thank you!


James,

Don't worry about those stock clicker settings, I gotcha covered. :)
 

James

Lifetime Sponsor
LIFETIME SPONSOR
Dec 26, 2001
1,839
0
Thanks for the cover :thumb:

I also should have checked this thread again before I pulled my slide out as Bruce has it right....it's a #7 slide and a A715/289R/A327/A487 needle. ;)

I should check into getting one of those chucked 03 carbs just so I can say I have that one too.
 

Faded

~SPONSOR~
Jan 7, 2003
842
0
Bruce and James,

Thank you! :cool:

I still can't believe that no one else has the PWK on thier CR... :think:
 

marcusgunby

LIFETIME SPONSOR
Jan 9, 2000
6,450
2
Some bikes are hard to jet no matter what-eric spoke or certain porting making the engines very hard to jet.Its due to the engines porting not being efficient at a certain rpm with a certain load.So you have to run on the rich side(on that curcuit) to compensate.I know jetting is throttle position sensitive but you understand my meaning.
 

CRPilot

~SPONSOR~
Apr 5, 2000
115
0
Faded,

I have tried a few more combos since I last chimmed in. What I found is that I don't think I'm fighting a lean condition (ping) at 1/4 anymore. I ran my pilot up to a 38 (from a 27 and all in-between) as well as richend the needle up to the 30-72 as well as the clip up into #4 spot. The end result was it was rich to the point of loading up in a matter of 5-10 seconds of not being on the pipe AND still pinging. I had the opportunity to run some quality oxygenated fuel and at the same time leaned everything out (back to the 30 pilot and stock 74 needle) and it ran great and no ping.

Since having the engine ported (mo better) it may need a higher octane fuel even though I requested it be set up for pump.

You may be fighting a lean spot, but is the ping from being lean or insuficiant Octane? Give it some thought. Race gas may end up being cheaper than all those jets.
 

Faded

~SPONSOR~
Jan 7, 2003
842
0
CRPilot,

Nice to hear from you again. :) I appreciate your ideas but I'm confident that it is indeed a lean spot. I have tried higher octane gas (110) and that solved the ping problem but I still had lean mixture symtoms. If you crack the throttle just off idle to about 1/4 it'll rev to the moon. The bike does not make good low end power and it gets better every time I richen the circuit. The pinging only occurs under heavier than normal load and when the bike temps are up. The gas I'm using (Sunoco :flame: ) isn't the greatest, but I'm still trying to source a better moto-specific gas.

I'm glad that yours is running better for you, have you run it w/the porting yet? If not, let me know what you end up with.

Thanks,
Andrew
 

CRPilot

~SPONSOR~
Apr 5, 2000
115
0
Actually the pinging started only after the porting was done. Prior, it ran fine, but still had the normal midrange hit the Hondas are know for. The porting smoothed it all out, but introduced the ping. It's possible that the porting highlighted the prior unnoticeable lean spot though.

As the temps drop in Wisconsin (34 this morning) any lean spots will stand out like a sore thumb, so I will be able to further ID the problem areas. For now it runs more than satifactory. In fact, 2 gear is obsolete and I'm considering going back to the 48t rear because it is almost to crisp off the bottom.
 

Faded

~SPONSOR~
Jan 7, 2003
842
0
My feelings exactly. I guess we both have about the same climate, 30's (low) to mid 50's (high) is about what we're seeing here. You're right about the lean spots standing out, it made a bad problem worse for me. I've been holding out for the 49 tooth rear until I can get the jetting solved. I'm a feather weight and every time I make a step in the right direction I start to question my ability to hang onto this thing. I guess I'll just have to learn to ride...
 

cr-man

LIFETIME SPONSOR
Nov 6, 1999
339
0
Has anyone been able to get a hold of AJ to ask him if he sells a Keihin carb kit and how much he wants for it? I tried his mail box is full. I am curious to hear his two cents.
 

bclapham

LIFETIME SPONSOR
Nov 5, 2001
4,340
0
service honda sells the keihin pwk 38mm airstriker from a 2000 CR250 for around $150. email him if you can i am sure he will sell you the carb with the ball park specs for the 02-03 bikes
 

marklb

Member
Aug 5, 2000
46
0
Guys, I have been reading all of your troubles with jetting the 03 and this is just what I went through. I have found something that works. The bike comes with a S-9 nozzle which is rich, I have spent atleast $100 on needles and could not get satisfaction. I did some research and found that the YZ250 uses a S-8 nozzle. Approx $16. I put it it and I am using the stock needle for 1500ft 95-100 degrees. Anyhow I even tried a differet slide. The yamaha # is 3tc-14141-s8. I have have Terry Varner deck & port the cylinder, I am running stk pilot, stk needle, 390 main, stk slide. Let me know if this works for you! Mark
 

Faded

~SPONSOR~
Jan 7, 2003
842
0
marklb,

I made the switch to the S-8 nozzle a long time ago, and you're right it definately help some. I'm curious about the slide, what year/model bike is it off of, what is the cut-away and how much $$ was it? I noticed that you're back to the stock slide, did the Yamaha slide not work?

bclapham,
You were right about the slides, that TMX slide I ordered was not even close. Just like you said, dealer item only and there are no options on cutaway unless you know another bike that uses the same carb with a different slide. Otherwise there is no way to look them up.

We made a trip out to the sand dunes yesterday. Super high load conditions, the sand was extra soft and I decided to run a paddle. I went off of previous notes for the jetting and ended up being waaaaay off. I had to jet richer than I ever have to keep it from knocking, but once I did she ran pretty good. There is one big hill that everyone races to the top and I was able to beat an '03 CRF450 with a Thunder Alley exhaust by about 1.5 bike lengths. No one could catch the guy on the YZF450, but I think his gearing plays to his advantage.
 

Dragmeistr

Sponsoring Member
Oct 14, 2002
149
0
I have the PWK on my '03 CR. I like it, it revs smooth and cleanly. Cant say that there was any real performance gain, other than no hiccups or jetting troubles. I got mine from CPW, pre-jetted for my bike. I didnt change much except for the main and needle clip. I believe that I have a 175 in it now. It fit fine, didnt have to do any mods. Jetting changes are easy, needle changes are super easy compared to the Mikuni. The only thing I do to make it a little easier is remove the 3 bolts on the case guard, this gives you a little more room to work. Dont remember if you asked or not, but other mods include, V-Force, SST pipe, Ti silencer, Boyeson exhaust flange. Any more questions, ask away. Hope this helped.
 

Faded

~SPONSOR~
Jan 7, 2003
842
0
Drag,

Thanks for the reply. The only other question I have is what are your current jetting specs?

Thanks again,
Andrew
 
Top Bottom