02 CR250 PWK 38 and # 6.5 slide

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8/30/2018 3:58 PM

Decided to try the famous Keihin Air Striker on the CR250. Got one at a decent price from a 2002 KTM 250. I had planned to rebuild it with a kit for a 2000 CR250 – since that is supposed to be about the best starting point with this swap. I’ve somehow managed to never have to mess with carburetors very much in spite of having had many bikes over many years – I guess stock jetting usually works. Anyway, that’s my excuse for not knowing much about slides. So will the # 6.5 slide that came with the KTM carb work fine, OK, or not at all? Or can I compensate somewhere else in the carb? I don’t see a #7 slide out there for much less than $70 – which of course is why I’m asking. Advice on the rebuild kit plan & slide selection would be appreciated.

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2016 YZ250X

8/31/2018 6:05 AM

The #6.5 slide is not ideal, but it will work fine in that bike. The 00' cr250 rebuild kit is also a good idea so long as you don't use the needle that comes with the kit. You'll want to use an NEDW needle in the #3 clip position, with a 42 pilot and a 172 main jet, and the air screw set at 1.5 turns out.

NEDW---- https://www.partzilla.com/product/suzuki/13383-37FL0?ref=5a77878e9329e098fcedea2aaeff653085536f51

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8/31/2018 7:08 AM

Thanks for the reply. I've yet to find a place that tells me what stock jetting was for a 2000 CR250 - is that what your recommendation is? The rebuild kits are a bargain compared to buying carb parts piece by piece, but then if I use almost nothing from the kit, it's not much of a bargain. Also, since my #6.5 slide is richer, would a leaner clip position be a good compensation - say maybe 4th position?

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2016 YZ250X

8/31/2018 7:52 AM
Edited Date/Time: 8/31/2018 7:57 AM

KX500 wrote:

Thanks for the reply. I've yet to find a place that tells me what stock jetting was for a 2000 CR250 - is that what your recommendation is? The rebuild kits are a bargain compared to buying carb parts piece by piece, but then if I use almost nothing from the kit, it's not much of a bargain. Also, since my #6.5 slide is richer, would a leaner clip position be a good compensation - say maybe 4th position?

The generic rebuild kit for an 00' cr250 will work fine in your carb( 02'KTM). You're simply not going to use any of the jettig, (pilot,needle,or main,) that typically comes in the rebuild kit. I listed the jetting above that you will want to use. A Suzuki NEDW needle in the #3 clip position, a 42 pilot jet and a 172 main.

Going from the 3rd clip position to the 4th would make it richer.

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9/1/2018 3:35 PM

Parts are ordered.

But the suspense was killing me and it was either do the carb swap or mow the lawn. Plus I had a 175 main and the used carb had a 48 pilot - anything to avoid mowing! And richer is safer, right?

So about an hour later, bike starts on 1st kick. A short ride around the yard (2 1/2 acres) and I'm smiling immediately! Definitely stronger low to mid range. Maybe not much different on top, but wasn't worried about that.

Probably best mod I've ever done on any bike - my last carb swap was nothing like this.

Kind of amazing that Honda went with Mikuni for these bikes, especially considering they own 51% of the stock in Keihin.

Jetting probably isn't optimal, but not a hint of 'ready to foul a plug' or any other obvious signs. I work on optimal as time allows.

Only problem so far is I need a super small hose clamp for fuel line and swap didn't take near long enough to get me out of mowing.

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2016 YZ250X

9/1/2018 3:54 PM
Edited Date/Time: 9/1/2018 3:56 PM

KX500 wrote:

Decided to try the famous Keihin Air Striker on the CR250. Got one at a decent price from a 2002 KTM 250. I had planned to rebuild it with a kit for a 2000 CR250 – since that is supposed to be about the best starting point with this swap. I’ve somehow managed to never have to mess with carburetors very much in spite of having had many bikes over many years – I guess stock jetting usually works. Anyway, that’s my excuse for not knowing much about slides. So will the # 6.5 slide that came with the KTM carb work fine, OK, or not at all? Or can I compensate somewhere else in the carb? I don’t see a #7 slide out there for much less than $70 – which of course is why I’m asking. Advice on the rebuild kit plan & slide selection would be appreciated.

Remember- you can always machine a #6.5 slide leaner into a #7 for a lot less money than it costs to purchase a new #7 slide.
RB Designs will do this for $16 plus shipping.

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9/2/2018 8:12 AM
Edited Date/Time: 9/2/2018 8:56 AM

40 wrote:

Remember- you can always machine a #6.5 slide leaner into a #7 for a lot less money than it costs to purchase a new #7 slide.
RB Designs will do this for $16 plus shipping.

Good info 40. I've had a couple of conversations with Ron (RB Designs) & he is a knowledgeable guy that is also a good dude. I'd recommend him to anyone looking for head or carb work.

OP - I've tested with a 00 Keihin PWK Airstriker & ran the stock-oem 00 needle with a 45 PJ, 175 MJ on 02-03 CR2's with good results. This is on moderate temps 70-90 deg., relatively no humidity & 0-1K elevation. It provided good off idle - lowend response through a beefy midrange & good topend. In my case I felt the mid-top dropped off a bit with the overev being more noticeable. It's a good trade off if you're more of a woods type - trail rider vs. MX.

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Speak softly and carry a big stick.

9/2/2018 10:59 AM

When i ran my 00 at altitude; 5k and up in Nevada, I simply did the "generic" two down on pilot/main, ran stock needle 2nd from top, and adjusted air screw every ride; it worked fine. Single track and desert that bike always did its job. I remember doing a top end, and was able to clean top of piston easily, as i had that good of a burn.

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Livin' the dream, two wheels at a time!