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Attn: 2002/2003 CR250 Keihin PWK Converts

Faded

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#1
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:
 

James

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#3
I have all the required carbs...I just haven't done the switch yet.
 

Faded

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#4
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

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#5
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.
 
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Faded

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#6
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

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#7
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

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#8
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:
 
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Faded

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#9
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

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#10
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

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#11
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

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#12
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

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#13
Bruce and James,

Thank you! :cool:

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

marcusgunby

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#14
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.