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Fcr 39 Carb giving me a headache fuel screw makes no difference to running

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Hi everyone, I am having some problems with my fcr 39 carb on my drz 400e 2001

I have rebuilt the carb, during which I found the pilot air jet was blocked and the emulsion tube was worn. 

I have been having some problems with the bike running correctly at idle to 1/4 throttle, my set up is as follows

The bike has a 3x3 mod

I live at sea level

Float height 9mm

165 main

Needle clip 2 from top

40 pilot jet

200 Main air jet
65 pilot air jet

The bike doesn't idle well, when the engine is hot and I snap back the throttle the revs take a couple seconds to drop back to normal.

What really worries me is that I've tried adjusting the fuel screw and I can wind it all the way in and the engine doesn't die! The plug is sooty when I remove it. 

Do you think I should go down another pilot jet size? Or Is there something else fundamentally wrong with the Carb? 

I'm considering the mid body strip down, is this likely to help? 

Thanks

 

Wes

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There are several possibilities. The one that you should hope for is that your pilot jet is too large and that is what is keeping the bike from lowering rpm as you turn in the screw. But based on the engines inability to hold idle, it may be that your mid-body is due for a rebuild. I assume that the carb is original and is now almost 20 years old?

Edited by Gary in NJ

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2 minutes ago, Gary in NJ said:

There are several possibilities. The one that you should hope for is that your pilot jet is too large and that is what is keeping the bike from lowering rpm as you turn in the screw. But based on the engines inability to hold idle, it may be that your mid-body is due for a rebuild. I assume that the carb is original and is now almost 20 years old?

Yeh, I think the carb has never been fully stripped down, I do have the mid body gaskets, am I asking for trouble if I tear it apart? 

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On 6/26/2020 at 7:38 AM, Wesley Ham said:

Yeh, I think the carb has never been fully stripped down, I do have the mid body gaskets, am I asking for trouble if I tear it apart? 

Give it a go mate ! 👍

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On 7/2/2020 at 11:37 AM, Tony Wyp said:

Give it a go mate ! 👍

Hi Tony, I replaced the gasket and the bike runs perfectly now 🙂

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MATE !!!!....you are a man after my own heart 😃

....give everything a go !

Good onya 👍

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Wesley, I'm at sea level, too.  In the event that it's helpful for comparison, then see this list for by Keihen FCR39 (non MX):

Mods: none

Main: 155

Main air jet: 200

Needle: OCEMN

Pilot: 45

Pilot/slow air jet: fixed

Pilot/slow air needle valve: 1.5 turns out

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