FCR gurus

[Joe_B]

Is this carb going to work OK for my FCR swap?

I picked up this 39 FCR from an eBay seller in China.

The guy had perfect feedback and communicated well, so I took the chance and bought it.

It is new and unused. By the numbers stamped on the body (3900K eaf29) it was originally from a KTM 250 XCF-W USA.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited May 23, 2017 by Joe_B
Fixed pic links

[HansLanda]

It needs an intake adapter. 

 

[ohiodrz400sm]

I've heard an E airboot will work but I can't confirm. If Jeff doesn't have any adapter's I have a blue one. I bought it for a 40mm experiment that I lost interest in.

[Joe_B]

I have an aluminum air boot adapter, E model intake manifold & clamp, JD JDS010  jet kit, and a flex jet

[ohiodrz400sm]

You're pretty much good to go.
What displacement? I had to drop to a 40 pilot with the JD needle on my 434. The kit comes with a 42.

[Joe_B]

2 minutes ago, ohiodrz400sm said:

You're pretty much good to go.
What displacement? I had to drop to a 40 pilot with the JD needle on my 434. The kit comes with a 42.

462, stock S cams, full FMF exhaust.

I live at 8600' altitude and typically ride between 6~10000'.

The JD kit was pretty much spot on for the 36 Mikuni, so I plan on going with what JD says.

The only deviation there being one step richer on the needle. My experience with several bikes at this altitude is to go slightly richer on the needle. They just seem to run better tuned that way.

[Beta300REcat]

5 hours ago, Joe_B said:

Is this carb going to work OK for my FCR swap?

I picked up this 39 FCR from an eBay seller in China.

The guy had perfect feedback and communicated well, so I took the chance and bought it.

It is new and unused. By the numbers stamped on the body (3900K eaf29) it was originally from a KTM 250 XCF-W USA.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SCORE!!!!!!!!

[Qqqqqqqqqqqq]

Interested to see how it performs

[Joe_B]

3 hours ago, NEKOOHC said:

Interested to see how it performs

I'll post up when I start the swap.

[30x26]

jd kit is an excellent product , however last honda fcrmx already runs dual taper needle and excellent accelerator pump settings . it's an highly refined product , with nice balance between pilot jet / needle diameter / accelerator pump and leak jet.

before swapping parts i would note down stock jetting and test it in stock configuration. a smaller main jet and 1 clip up or down may be all you need to get a 95% perfect jetting

Edited May 24, 2017 by 30x26

[crimedog]

18 hours ago, ohiodrz400sm said:

You're pretty much good to go.
What displacement? I had to drop to a 40 pilot with the JD needle on my 434. The kit comes with a 42.

Do you mind if I ask how your bike ran with the 42 pilot jet that you changed to a 40?

[ohiodrz400sm]

Do you mind if I ask how your bike ran with the 42 pilot jet that you changed to a 40?

Like crap . It was a sputtering, bogging, stalling mess at any throttle movement up to 1/4 throttle.

[Joe_B]

And here we go............

 

[Joe_B]

Full choke and a twist of the throttle and it fired right up and idled. Turned off the choke after about 10 seconds. Throttle felt crisp.

Only ran it for about 20 seconds and then shut it down because I used some RTV to seal up the oil separator box and I want to let it cure good before I get oil in there........but I had to at least fire it up!!!

 

Anyway..........I will report back later after a ride.

[Joe_B]

After the first test ride...........

Starts quick and easily with the engine cold or hot.

Idles great at 1550 rpm.

Runs smooth and pulls cleanly from any rpm or speed.

Throttle is crisp and responsive and even better than I would have expected. You can snap the throttle open from idle with absolutely no hesitation.

 

Although not really the performance improvement I was hoping for. It pulls harder everywhere, but not what some would have you believe.

3rd gear wheelies on the throttle? Nope........ain't happening. 

I do live at 8600' altitude. The performance difference between here and sea level is SUBSTANTIAL.

 

JD red needle clip in 3rd slot from top

155 main

40 pilot

Flex jet at 1.5 turns out

Float height 9mm

Idle air jet 100

Cold start jet 85

Leakage nozzle 50

[ohiodrz400sm]

 
Although not really the performance improvement I was hoping for. It pulls harder everywhere, but not what some would have you believe.
3rd gear wheelies on the throttle? Nope........ain't happening. 
I do live at 8600' altitude. The performance difference between here and sea level is SUBSTANTIAL.

That's crazy. I have never ridden at high altitude, I didn't realize the loss was that significant.

A well tuned 400 will pull the front end with low end power down here.

[Joe_B]

1 hour ago, ohiodrz400sm said:

 

That's crazy. I have never ridden at high altitude, I didn't realize the loss was that significant.

A well tuned 400 will pull the front end with low end power down here.

 

Don't get me wrong, it runs pretty strong. I just don't think it lives up to some of the exaggerated claims I have heard.

The best thing is that it runs well EVERYWHERE. From low to high rpm and any throttle opening.

It feels like it is going to work really well off road.

[jjktmrider]

What gearing a person is running has as much effect on 3rd gear wheelies as a couple k elevation changes , but there is some good hp loss as you get higher , I forget the exact figure per 1k.  By 8500ft it would add up to quite a bit . 

 

 

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Edited June 1, 2017 by jjktmrider

[ohiodrz400sm]

I would think the S intake cam is also stifling alot of the gain that would otherwise be realized from all the other modifications.

[Beta300REcat]

4 hours ago, Joe_B said:

Don't get me wrong, it runs pretty strong. I just don't think it lives up to some of the exaggerated claims I have heard.

The best thing is that it runs well EVERYWHERE. From low to high rpm and any throttle opening.

It feels like it is going to work really well off road.

Not so much the power, but the response, which it seems you have. However, it is the cornerstone for all the other mods.