440ex FCR carb Jetting

[sodbrother]

Last night spent about 2 hours reading all the past posts on the FCR carbs.... Well I still have no clue as to where I should start out with my jetting for my new FCR41 and after reading the posts I am not sure if I even got the right carb ????

I decided the 440 kit and cam would give me all the low end power I could want so the FCR41 should help me on the topend ?

What I just had done to my 400:

440 Big Bore kit
Stage 2 Hotcam
Titanium oversized valves
Titanium springs
Head Flowed to the walls
higher Rev limiter
LRD Ceramic Exhaust
Lightened Flywheel
13.5 to 1 compression
Re-surfaced the rockers
110 octane race gas (local shop recommended)

Should I be running 110 gas to break in the engine and jet the carb ?

I have installed the FCR41 on the bike with:
180 main
52 pilot
Needle 3rd position (from bottom)

It was very nice of Sudco to charge $450 for the carb and give absolutely NO instructions what so ever.

My local dealer didnt seem to knowledgeable about the jetting on the 41. He said he rarely sells one cause nobody can afford them these days....

Do you guys think I am at a decent starting point ? I want to make sure I dont run her to lean. Should I mess with any of the air mixture screws ? How do I adjust them.. meaning in does what ? out does what ? which one is which ?

Regards,
Sodbrother

[400MXer]

I dont' have any info for ya but i will be joining you pretty soon. I'm getting a 41mm FCR too. if i get instructions with mine i'll post them.




my thoughts are to use your stock carb for the break in then, put the 41 on after and jet it. just try the posistion that you are at then go from there. Jetting is all about Trial and Error.

[nakomis0]

180 sounds like a good start to me, put the needle someplace in the middle.

Then just standard jetting procedure.. set the main, then set the needle, then set the pilot.

Only do one change at a time.

[MIKE400EX]

I have pretty much the same mods, just a little less compression.
Main:178, pilot:52, air jet:200, needle: 4th groove down. Probably could go with a 180-182 main, especially with this cold weather lately. The above works from 0 to about 1500 foot altitude.

[sodbrother]

Hey Mike, thanks for the info. When you say "air jet:200" is this stock or did you change that out ? Where is that located ? did you mess with any other adjustments ?

Thanks,
Sodbrother

[MIKE400EX]

If you got it from Sudco then it should have the #200 air jet already. The Sudco website has some tuning info. I'll PM you some other tuning tips.

[sodbrother]

I started her up earlier today and she is running but not real great. Seems to be some hesitation in the throttle especially at low RPMs. I didnt get a chance to open her up that much.

I cant find anything on Sudco's website except parts diagrams ?

Sodbrother

[MIKE400EX]

Try this: http://www.keihin-us.com/tune.htm

[terko440]

Hey mike, I was wondering how you like your fcr 41. I've wanted to buy one of those since i've heard of them but all the different answers I get stop me from getting one. Some people think the 41 is overkill in reference to the 39. What do you think. Your bottom doestn suffer too bad does it? I really want to get the 41 just because i guess, and with the future bikes coming out it might be a better seller. Please get back to me and let me know in detail the performance gains you noticed and how well you like it! Thanks, Tim

[shaneb]

First of all I doubt can can really tell the diff between a 39 and a 41 ...

my 41 in my 493 had a 184 and was a bit ritch ....

Shane