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My FCR-MX 41mm conversion Project (XR650L)

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I just wanted to post some pics of my new FCR-MX 41mm carb to show the how well the NOSS fcr adapter fits and looks. This is a newer type FCR-MX carb with the upgraded AP linkage. This model also has an access hole to remove the needle without removing the whole cap. In the pictures I had just epoxied the airbell adapter and wanted to show how well the adapter fitted. The insides are very smooth. I ordered a EMN and EMR needle for it and a handful of pilot jets. I will be testing soon once I get all my parts.

carb1.jpg

carb2.jpg

carb3.jpg

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Not sure the seller on ebay didn't know. I would think it would be off a 2007 or newer CRF450 or WR450 because it is the new style FCR-MX with the newer AP linkage and new longer style needle.

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I put the carb in the frame and I had to remove the choke because it was really really tight. I guess I won't be removing it anything soon. Its a good thing I can turn the carb sideways to change the jets. When installed it fits perfectly. The stock throttle cables don't fit as expected. The pull cable can be used just barely but your at the very end of the adjustments with only a couple threads holding and the throttle stills has a little too much slack. The pull cable casing needs to be 15-20mm longer and the opposite is true of the return cable. If the pull cable didn't have a larger threaded end on the end that connects to the throttle grip I could have just switched cables but unfortunately I couldn't.

Also the stock choke cable and plunger seems to be a direct fit so I am hoping I will be able to use it. I plan to block off the hot start as I don't see the need for it. More pictures to come.

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You can get better/longer cables for it from Sudco or Motion Pro (Sudco uses Motion Pro cables). When I installed my FCR I also changed out the OEM throttle housing for a Motion Pro Push/Pull assembly, as it was only $19 and is 10,000 times better than the OEM Honda unit. :thumbsup:

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You can get better/longer cables for it from Sudco or Motion Pro (Sudco uses Motion Pro cables). When I installed my FCR I also changed out the OEM throttle housing for a Motion Pro Push/Pull assembly, as it was only $19 and is 10,000 times better than the OEM Honda unit. :thumbsup:

Thanks for the tip Old Dog. The guy who sold me the carb is sending me a free set because he told me that my stock cables would fit. I'll see what kind of cables he sends me and if they are not satisfactory I will definitely pick up a throttle assembly at the same time. Is this the one you got? http://www.motionpro.com/motorcycle/partno/01-0073/

Edited by D0T-C0M

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Yarp, that's the one DOT-COM ... it looks like it costs even less now ... or maybe that $19 was what I paid in Canadian $.

That unit is as basic as it gets for a Push/Pull assembly, it comes apart and goes together in about ten seconds ... no stupid guides to get in place like the OEM one. :banana:

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Old_Dog The stock throttle cables ends are different in size. One is a M6x1.00 and the other is M7x1.00. Does this new throttle assembly have one hole bigger bigger than to other too?

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Old_Dog The stock throttle cables ends are different in size. One is a M6x1.00 and the other is M7x1.00. Does this new throttle assembly have one hole bigger bigger than to other too?

Nope, that's why when I ordered my FCR from Sudco I asked Chad to send me the cables with the ends to fit the Motion Pro Push/Pull assembly instead of the OEM Honda one.

If the cables that the guy you bought the carb from sends you don't work (which I doubt they will), you're better off to call/email Motion Pro and tell them the model of carb (FCR MX) and that you're going to be using their Push/Pull assembly. They'll be able to hook you up with the correct cables, no problemo. :banana:

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glad u finaly got it and get to have her in and enjoy the benefits soon

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Thanks Denn10,

I started it up yesterday for the first time and did it ever start easy. Its no way close to being tuned but it does look promising. I haven't gotten my throttle cables yet so I was operating the carb by hand. My EMN and EMR needles aren't in yet but the NCYP that I tried in it is pretty close. I'm still getting a bog when snapping it open from idle that I'm sure a smaller leak yet will fix. Its going to be a fun next couple days.

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Dot-Com, how is the carb working for you?

Would you happen to have the casting # off the carb?

I would like to get one for my bike but want to make sure I get a 41mm carb.

Thanks

Jonny

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The carb is awesome but its been brought to my attention that the carb I have is possible a 40mm carb but I haven't had the time to take my carb back apart to confirm. Apparently you have to measure the opening at its smallest point in the venturi but I had measured 41mm at the outer edge of the carb but like I said I'll have to confirm later when I can find some time. I am extremely happy with my carb though. The AP pump works awesome. Throttle response is immediate and the bike pulls hard. The NCVT needle works very well.

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Dot-Com,

I found this the other day when I was trying to figure out what the 41 mm FCR-MX came on, and it may help you figure out what carb you have.

CRF250X * California model

Carb size Casting # year

37mm FCR02A and FCR03A* - '04, '05, '06

37mm FCR02B and FCR03B* - '07

37mm FCR02C and FCR03C* - '08

CRF250R

Carb size Casting # year

37mm FCR01A.A - '04

37mm FCR01B.A - '05

40mm FCR01C.A - '06

40mm FCR01D.A - '07

40mm FCR01E.A - '08

Please let me know when you do figure it out. I'm glad to hear that you are happy with yours. I'm for sure swapping out the CV carb for a FCR as soon as I can find out which one I need.

Thanks for your help Jonny

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Dot-Com,

I found this the other day when I was trying to figure out what the 41 mm FCR-MX came on, and it may help you figure out what carb you have.

CRF250X * California model

Carb size Casting # year

37mm FCR02A and FCR03A* - '04, '05, '06

37mm FCR02B and FCR03B* - '07

37mm FCR02C and FCR03C* - '08

CRF250R

Carb size Casting # year

37mm FCR01A.A - '04

37mm FCR01B.A - '05

40mm FCR01C.A - '06

40mm FCR01D.A - '07

40mm FCR01E.A - '08

Please let me know when you do figure it out. I'm glad to hear that you are happy with yours. I'm for sure swapping out the CV carb for a FCR as soon as I can find out which one I need.

Thanks for your help Jonny

I think the 41mm came on CR450s for a few years before they went FI. I think that is what mine came off of... heck... mine could be a 40 mm for all I know... it works:smirk:

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I think the 41mm came on CR450s for a few years before they went FI. I think that is what mine came off of... heck... mine could be a 40 mm for all I know... it works:smirk:

after I bought my fcr mx i figured out it was a 40mm, off a, 04-crf-450r, and thought:banghead: it would not run as well as a 41mm. then i read that , (i think it was Sudco) did a test on a dyno with 39,40, and 41mm with a xr650l and the difference was so small, seat of the pants, you wouldn't be able to tell. i'm very happy with my 40mm fcr mx.

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after I bought my fcr mx i figured out it was a 40mm, off a, 04-crf-450r, and thought:banghead: it would not run as well as a 41mm. then i read that , (i think it was Sudco) did a test on a dyno with 39,40, and 41mm with a xr650l and the difference was so small, seat of the pants, you wouldn't be able to tell. i'm very happy with my 40mm fcr mx.

The smaller throat carbs may actually work better in the sweet spot of our bikes' powerband. Larger throat carbs tend to do well at WOT/high rpm. How often do we ride our bikes high in rpms? I suspect not many. For snap and grunt, the 39mm may be the best. :ride:

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The smaller throat carbs may actually work better in the sweet spot of our bikes' powerband. Larger throat carbs tend to do well at WOT/high rpm. How often do we ride our bikes high in rpms? I suspect not many. For snap and grunt, the 39mm may be the best. :ride:

Sounds reasonable.

The only Sudco FCR kit I see for the XR650l is 41mm. If a smaller size gives better low to mid rpm power, I would go that route since it fits my riding style better.

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