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removed airjet - fcr41mx - won't idle

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i read on some posts here that many of you do remove air jet. i took it out and bike seems very lean. it wont idle.

is air jet not pilot airjet you guys talk about when you say to remove it?

that is my setting:

fcr41-mx,full leovince exhaust,400 cc stock

200 main air jet

100 air jet (the one i removed)

42 pilot air jet

190 main jet

airbox modded (wide open on top and right side)

2.1/4 turns out on screw

sea level

what's wrong with idle circuit?

bike pulls strong but wont idle.

p.s. another thing is if i pull the choke bike revvs too much:eek: .

:worthy: :worthy:

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That's a big carb for a stock engine, isn't it?

It's definitely the air jet, and not the pilot jet, that is removed on the FCR-MX 39. (I don't think you can remove the pilot jet on any carb.) Whether removing the air jet on a 41 is something you want to do someone else will have to say.

But if your pilot circuit is so lean that the engine won't idle, then 2 1/4 turns on the air/fuel screw -- which tunes the pilot circuit -- is too much. I would try 1 turn out and see if that makes a difference.

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Removing the pilot air jet (Marked #100 in the carb bell, the larger of the two inphysical size) is done on FCR-MX carbs sold after July, 2006. This is not a firm rule. It really has to do with the manufacturing date. No idea of the age of your carb. How long was it sitting on the sellers shelf and so on. Did you try it with the Air Jet installed?

What fuel screw do you have in the carb as a 42 pilot is a tad small too.

Finally, as Harp said, a 41mm is too big for your engine. Off idle response is going to be poor as will full thottle.

Choke on, the bike will rev to about 2,500 rom, nearly double a regular idle, this is normal.

You also need to confirm that you do not have the idle set too high and let us know what needle and clip position you are at.

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needle is emr clip 3

my fcr is been probably sold before july 2006

i'll put the air jet back in...thanks

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Needle and clip position sound reasonable (in fact that is exactly what I run).

Let us know how you make out after the Pilot Air Jet is back in. You may need a 45 pilot jet, but only setting the fuel screw can tell for sure. I hope you have an extedned fuel screw too. To set the pilot circuit, gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly).

*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***

Turn the screw in until the idle becomes rough or the bike stalls.

if it stalled, open the screw about 1 turn. Restart it and slowly screw it in till you can just perceive a change.

If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.

Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle, at the correct RPM.

If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.

If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.

If the idle speed is too fast or too slow, adjust the idle speed knob to return the bike to a normal idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle and the idle speed is at 1,500 RPM.

Be sure to keep notes of your settings. You may find you need to make a change, say if you're riding in the mountains or down at the beach. Returning home, it is a simple matter of referring to your notes to restore things.

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it's a 41 fcr-mx for sure. it has a tunable ap and no leak jet. don't know the bike it comes from. the slide was in place..never had it out.

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removing the pilot air jet is only on the aftermarket fcr-mx.

if your fcr "came from a bike" it does not apply.

did you have the carb running on your bike previously?

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it can be an aftermarket fcr-mx.the guy who sold it to me sayd he had it from ebay.

the byke ran well before but i had a 48 pilot jet and 100 air jet in. it idled a bit poorly but now it doesn't idle at all:

as soon as it starts, it will die unless i throttle it.

it seems to not react to the fuel screw. i tried 3.5 turns out

or all the way in but still same problem...

what do you think?

should i try to put the 48 back in and leave the air jet out

or should i take the carb off and put back the air jet directly?

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