CR250 Keihin Conversion - JD Jetting Help

jonahdru222
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jonahdru222
Edited Date/Time 5/4/2018 11:23am
I have an 06 CR250 and the slide on my Mikuni is all broken at the bottom so I was just going to go ahead and do the Keihin conversion.

I have a few questions. First, does it use the same throttle cable? Second, does the TPS plug right into the CR plug? Lastly, does it use the same reed boot?

I plan on buying it through JD Jetting so I can get the JD jetting kit. Does the kit include tips on jetting if you have an aftermarket exhaust, or is it only for optimizing factory specs?

TIA
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omalley
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omalley 4/30/2018 12:55pm
4/30/2018 12:55pm
My JD carb for the 02 came with baseline specs, several needles, a couple mains and pilots, and charts for elevation. I don’t think it had anything for modifications.
Mr Happy
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Mr Happy 4/30/2018 1:34pm
4/30/2018 1:34pm Edited Date/Time 4/30/2018 1:37pm
Same cable and slots straight in to the standard inlet and air boot. Lube up the engine side though as it's a slightly larger diameter than the Mikuni, and the body is slightly longer so is a little more fiddly getting the air boot on with the subframe in place. Can't help with the TPS plug.

Can't help with jetting as the climate in the UK is more extreme than anything you'll experience, so the JD kit would be useless for me. I started with the standard settings for the RM250 although ended up a long way from that.
jonahdru222
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jonahdru222 5/4/2018 11:23am
5/4/2018 11:23am
Can anyone help with jetting? I'm in no way a jetting guru. Stock bore/stroke. PC pipe shorty exhaust. Straight VP T2 40:1. 500' elevation. Texas climate.

Says to start in the middle with the needles at Red #3 and a 172 main. Doesn't look like it came with pilots. What would be yalls recommendation? I know the fuel might change things up a bit.
F150Motocrosser 5/4/2018 1:06pm
5/4/2018 1:06pm Edited Date/Time 5/4/2018 1:07pm
jonahdru222 wrote:
Can anyone help with jetting? I'm in no way a jetting guru. Stock bore/stroke. PC pipe shorty exhaust. Straight VP T2 40:1. 500' elevation. Texas climate...
Can anyone help with jetting? I'm in no way a jetting guru. Stock bore/stroke. PC pipe shorty exhaust. Straight VP T2 40:1. 500' elevation. Texas climate.

Says to start in the middle with the needles at Red #3 and a 172 main. Doesn't look like it came with pilots. What would be yalls recommendation? I know the fuel might change things up a bit.
My recommendation would be to do exactly what "they" say and start with the needle clip in the middle position. How does it run? Noticeably lean? Or perhaps a little fat on the bottom? Also - how does your spark plug look? The answers to these questions will dictate your next move.

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