FCR Jettin' Problem

[X400EX]

I've recently installed a 450r FCR 41MM on my 400EX. It all fits, but I barely can open it upper 1/4-1/3 of throttle or it will totally die.

My needle is at the 3rd position from top,

Tried with 155, 175 and 180 Main jet.

Tried with pilot #42 et 45.

Don't know about my fuel screw...

I've also tried with closed air box and no air box, even no filter at all and I barely see any difference...

My spark seems dark, whitch is probably too rich at idle.

Why can't I Rev it up more than 1/3 throttle?

Thanks.

[zrpilot]

More info please. IS the choke or enrichment circuit on? How are you accelerating? Slowly or are you smacking the throttle open? Are you riding it? What is the temp? How does it idle?

[X400EX]

Hi zrpilot, thank you for your quick anwser.

With the choke on, it is barely better, it only runs faster on idle.

I'm accelerating slowly and when I get like the 1/3, it is dying. If I snap, it does the same thing when I pass that 1/3 position.

I'm on neutral, the temp is like +10 degrees celcius in a garage.

Idle runs very well, may be a little rich I guess (spark plug dark)

Thanks you for your help.

Edit : When I say dying, it's kinda like I would kill the motor with a switch, but if i release the throttle, it comes back running well on idle.

[zrpilot]

As it starts to die, can you let up on the throttle and will it return to idle?

Here is what I'm thinking: If 1/3 throttle is close( by this I mean close to the position where it is dieing, then the carb is most effected by the needle circuit), then I think you got a needle issue. I'd do somthing radical and hope it gets worse or better. I'd raise the clip position all the way to the top notch and see how it runs. IF worse, then I'd go to the bottom and then see how it runs.

This is uncharted territory, thats for sure, I never have heard of trying this carb on a 400EX.........

[X400EX]

That's what I was thinking, the needle.

It was on the last position (richest), I putted it on 3rd from top, got the same issue.

When it starts to die, I'll have to confirm if i can let it open. I think I was, cause it was rev'ing up but boging.

Thank you again for your help zrpilot, I'm gonna come back tomorrow and let you know any updates,

If someone has another idea, please let me know too!!

Thank you.

[zrpilot]

when it dies, does it cough and sputter, or simply die like you have turned off the key?

I hate to say this, but it is possible that this carb may not work on your machine. I had a Sudco 39MM FCR on my 416 EX and had issues with it. Tuning it was a pain. My 400EX running the FCR was real finicky about things like accel pump timing and duration, main jet, needle, and it HATED to be smacked opened and always had a bog when doing so. There are people here that like the FCR and have had good luck with the carb, I did just had trouble. Mine runs much better with an '04-'05 450R carb (non-FCR type) and there is alot more experience on the boards here with that style carb.

[X400EX]

When it dies, I'd say that it's like I would have turned off the key.

I'm gonna try as much as I can to make it fit. I'll let you know any updates, thank you for your precious help.

[zrpilot]

X400EX you are very patient, I would have ditched that carb and gone back to the stock one.... good for you! Stick with it man!

OK the fact that it dies like you've turned off the key is interesting. Do you think it is still sparking when it dies? Do you have an inductive timing light you could hook up and see if the spark plug is flashing the timing light as it dies?

If I were you I'd RADICALLY change the jetting on the main. Put the needle in the middle notch. Then try the smallest jet you have (I may have some jets laying around that you could try). If that is no change then try the largest....

Some how we need to get it to run, even if it runs really bad.

[drew416ex]

Give sparks racing a call. You dont have to say what it is off of, just say its a 41mm fcr and tell them your mods. They can usually give you a pretty good starting point. They have always been able to help me with my stock or 39mm fcr.

[X400EX]

First of all, thank you for your anwsers.

Here's the update : I've backed up to 148 MJ and tried all the positions on my needle; the best running was when the clip was at the last clip, the richest.

I've tried 2 differents Pilot Jet, #45 seemed to run better than #42. Was able to have more revolutions with #45.

I've been also able to reach the 3/4-WOT a few times while it was reving up enough from 0-1/4, I had to snap to WOT very quick and after a couple of backfires, it runned well at WOT while holding it. It is like my 1/4-3/4 throttle position doesn't work at all. It is totaly dying in this range.

I've also noticed that my 400ex was doing backfires if I was holding it at when it was dying, like at the 1/4 of throttle.

I've also tried, as a test, to completely remove the Needle. Then, I only got 3/4 to WOT but I was easly running in this area. I had no idle though.

Thanks you for your help. I may call sparks in last resort cause I don't speak english very well! :)

[zrpilot]

OK so do you think it is lean? What are the numbers stamped on the needle? Maybe ordering a new, richer needle may help. It should say somthing like: OCEMR or OCEMN....

[Wingnut]

Have you tried cleaning the carb really good? I've had carbs act like that before and there was just some dirt hidden somewhere in there. After cleaning it a couple of times and blowing it out really good with compressed air it worked fine. I have been thinking about trying this myself since I have a 400EX and one of these carbs on my 450R.

[drew416ex]

Backfireing is usually a sign of it being a little lean. Like zrpilot said, get the numbers off of the needle and get a richer one. You will probably need a little richer main also, 148 is kinda small.

[X400EX]

Yeah, I've cleaned the carb very well and many times when I got it. It is nearly new.

Indeed zrpilot, it was written something like that on the needle. I think it was OCEMR.

So I'm gonna look for a richer needle.

Would it helps if I'd put a richer pilot jet too?

[GPracer2500]

Make sure the slide plate is installed correctly. It's really easy to put them together upside down.

Goes like this even though it seems like it should go the other way around:
http://img.photobucket.com/albums/v699/burned-drz/slide.jpg

[zrpilot]

I'd try an OBELQ needle or even richer the OBEKQ needle.

As far as the pilot, it only effects idle to about 1/8-1/4 throttle.. if it idles fine and the idle mixture screw is less then 2.5 turns out from lightly bottoming, then I'd leave the pilot alone.

[drew416ex]

The pilot affects the idle to 1/4 throttle circuit. If you say it ran better putting a richer pilot in it, it wouldnt hurt to go up another size or two to see if it makes a difference, but it wont affect your 3/4 - WOT circuit. Here is a diagram of the jetting circuits. We mainly focus on the slow jet (pilot jet), needle taper, clip position, and main jet. Mainly it will help you determine where your problem is.

[X400EX]

Thank you all for your help again.

I'm gonna look for a richer needle.

Is that the correct way for the side plate ? I got it like that :

[GPracer2500]

Can't tell. The slide plate is on the other side.

[X400EX]

Sorry, I thought you meant to talk about that plate. I don't know much about FCR's.

I'm gonna look myself probably tomorrow if it's in the good way.

Thank you for your help.

[GPracer2500]

So we're clear, the slide plate is the thin plate shown on the right in the picture above. It fits right up against the slide, on the engine side. The square end (the end with the hole) must be facing down. It can be assembled with the other way and kinda even looks like it's suppose to go the other way. But the carb will not function properly if that plate is upside down.

[X400EX]

Thank you GPracer2500, with that new explanation I understand perfectly now. :)

Tomorrow, I should be able to take a look at it and see if it's facing down or not.

[X400EX]

Ok guys, I think I got some good news.

I've done some other tests tonight.

First of all, I've changed the 148 MJ to the 175AB.

I've made sure that the needle was at the richest position and did some run test on neutral.

No air box, was not able to get 1/4 - 3/4 as usual... So, I got a simple idea to test the mixture.

I've removed the Uni air filter and putted my hand to block like 80% of the intake to make the mix of gaz more rich... Surprise! The quad was running not too bad! Some bugs there and there but it was reving up and running like "ok". Was meaning that it is truly lean on this setup.

I've then installed back my airbox and lid, started the 400ex again and I'm now able to rev it up! I can't snap it to WOT quickly thought cause it's dying. There is still like a bug at mid range (1/4-3/4) if I snap so I think this is saying that my needle is really lean!

What do you think?

If I want to run open box, considering that it is dying from 1/4 at 3/4 with this setup, should I change my needle to OBELQ or the OBEKQ? The actual needle I have is OCEMR.

Thank you for your help.

P.S : My slide plate was in the good way. :)

[zrpilot]

Those needle numbers were from an old Excel jetting spreadsheet I bought a long time ago, they may be out of production or unavailable.

Refer to the www.sudco.com web site for available needles

Needles (http://www.sudco.com/vol33/113.pdf)

[X400EX]

Thank you zrpilot, I'm gonna take a look at this with my local dealer.

[X400EX]

Alright, I've now got a richer needle installed.

It has help a bit, but still has big flat spot on middle range and I can't snap it from low rev or idle... It will die.

I've noticed something : I've removed my carb after a test run then hitted the throttle and no gaz got out off the carb. I mean, I think it is suppose to propulse a small line of gaz into the motor when i hit the throttle to WOT? That thing is usefull in winter here in Canada for cold starts...

What's going on with this carb?

BTW : I'm able to run with it, it runs much better than my stock one and gives great power. Only have that problem on mid range... Could the absence of this small gaz jet into the carb each time I hit the throttle could make an influence?

Thank you for your help.

[zrpilot]

Originally posted by X400EX
Alright, I've now got a richer needle installed.

It has help a bit, but still has big flat spot on middle range and I can't snap it from low rev or idle... It will die.

I've noticed something : I've removed my carb after a test run then hitted the throttle and no gaz got out off the carb. I mean, I think it is suppose to propulse a small line of gaz into the motor when i hit the throttle to WOT? That thing is usefull in winter here in Canada for cold starts...

What's going on with this carb?

BTW : I'm able to run with it, it runs much better than my stock one and gives great power. Only have that problem on mid range... Could the absence of this small gaz jet into the carb each time I hit the throttle could make an influence?

Thank you for your help.

It sounds like you have no accelerator pump stream? I don't know this carb very well, but it seems to me that it should have an A/P. If the A/P is not working, then I think the carb would act as the following:

1) If you accelerate slowly the machine would respond.
2) If you smack the throttle open it would fall on its face.

[X400EX]

Exactly zrpilot. That's the way it acts.

I don't know much either about this carb. :S

How this accelerator pump works?

Thank your for your help.

[X400EX]

Wow, double post. Sorry for that.

[2muchquad]

You'll need to get the ap working.You can replace the diaphrams in them.Make sure the carb bowl isnt dirty.Once you get it working you can play with the ap squirt and duration with different leak jets and the "oring mod" which got rid of the bog when snapping to wot from idle on my 385ex.Thats a whole different can of worms though,one thing at a time,get your ap working first.You'll love this carb wants its dialed in,its like another machine imo;)

[X400EX]

Alright.

Well, I've been running since 2 months with this carb. It runs so well, I love it! Just can't snap to W.O.T. from idle. Otherwise, I've nearly been able to jet it perfectly.

The AP is not working properly, it is like the gas get out but not as a squirt. It's just like flowing slowly... I have replaced the diaphram and spring, may be something block the hole of this "brass thing" (from where the squirt should be out from).

How could I test if something blocks the hole of squirt?

Thank you for you help.

[2muchquad]

The best thing i can say is take it apart and give it a good cleaning.Use compressed air to clear ALL the ports and what not.Can you modify the squirt on that carb?They have subtle differences through the years.Yours is probably dumping too much fuel when you try to go wot from idle,you can get it better but some engines dont like wot from idle and you'll never get rid of the bog completely,however it usually isnt bad when actually riding.Do a serch on "leak jets".Thats something else to chew on:D