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Kehin 30mm PD Carb

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We know it will fit, but who is running one? How did you jet it? What modifications have you done to the engine on your 230?

Coeshoe?

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Cdaledh,

I'm still testing it. I will be trying it again on a test coming soon with a full on race engine we are building. I did try it on my bike when I first bought it, and it seemed to improve the power up through about 3/4 throttle, and then felt a little weaker.

After further examination, the intake manifold is formed just like the stock carb opening.(not fully open/round at the top) The stock manifold becomes restrictive after @ 3/4 throttle.

Have since modified a new manifold to match the carb opening, and also the port flange area. This race engine will have the head ported and modified to match, and we will test very soon. I expect stellar results!! I predict 25+ HP at rear wheel. Will do back to back tests with std 26mm carb and also a Keihin 28mm FCR flat slide carb with acc. pump. I will post when the results are in.

Mike

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Mike, I have been looking seriously at trying a Keihin 28mm FCR flat slide carb with acc. pump. on my Honda FTR223 street tracker. While researching aftermarket parts for my "Tracker" on the web, I have run across several photos and broken translated Japanese text of "pre jetted kits" offered in Japan along with many owners that have installed them. However, they all make reference to a 30mm FCR carb which seems to me is too much carb for a mildly modded street or dirt bike unless it has been sleeved down a few mm with some type of insert..... Karl

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Karlznet,

The stock intake port diameter on a 230 is 28mm, and the intake valve is 31mm. The XR250 comes standard with a 30mm carb. In fact, the carb is the same casting as the 230's carb! It will bolt on with minimal mods.

Honda's come stock with conservative carb sizing. I think the 30mm carb will prove to be beneficial in adding power. I will know for certain soon.

The biggest problem I face with the FCR is fitment issues. As anyone that owns a 230 knows, the carb is tucked in pretty tight!! Because of it's design, the FCR is bulky. We'll see......

Mike

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The XR carb is now on my bike. Spent a little time fiddling with jets tonight. Coeshow is definately right, the carbs are practically identical....the slides are even the same. The difference is the size of the throat and outlet spiggot.

I transfered existing jetting from the stock carb to the XR carb. 1/4-1/2 throttle is the same as the 26mm, but I had to go fatter on the main. It now has a 145...may need more. may also have to pull the needle a notch or two.

I also have to do some major rework to the intake tract in order to use the carb to it's fullest.

Bottom end is a bit softer, there is a slight flat spot in the midrange, but holey smokes batman, the top end flat screems!!

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Port matched the intake manifold to the new carb!!!

Well, the Power Up needle is worthless for this carb. I put the clip on the bottom, and I still had the flat spot.

I installed the OEM CRF230 Needle with the clip in the middle, and whallah, the flat spot is all but gone. I just need to do some tuning with it and the main.

I also had to drop the Pilot to a 42. The Fuel screw is now @ 1.75 turns.

The OEM needle has a much more aggressive taper, allowing more fuel from the main earlier in the throttle opening.

I also stepped up to a 145 main jet...it's a little fat...also needs some tweaking.

so far it is running good!!

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Goin trail ridin today!!! should be fun!!

oh...fyi, the 145 main was not fat!!

She now has a 150 main!!

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So far so good!!! Lost a little off the bottom and lower midrange, but it is much easier to keep the front end in the air due to the stronger top end. It actually has a bit of a "hit" on top now. It's still a little lean...may raise the needle a notch to get better mid throttle response. Also will try a 152 main.

Trail Milage on a relatively spirited ride was ~ 30-35 MPG

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