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54 minutes ago, Drz400nlm1990 said:

Its too rich but i already have a 40 pilot jet in it, which according too many should already be very lean. I think my trouble is coming from the float level as i measured it wrong, could that be possible? And i think i put the vaccun seal gasket upside down. Other then that should i go down to a 38 pilot? The who carb was already taken appart and cleaned and rebuilt with new parts

First thing you need to do is pull it and make sure it's assembled correctly and the float level is correctly set at 8mm. The level of the float should be set when the valve closes, but that little spring loaded pin is still extended. If you turn the car upside down, the float weighs enough to collapse that pin and the level ends up way way low.

Make sure the vacuum release plate is correctly oriented also. If that's upside down, and the seal is incorrectly set, it's never going to idle and draft over the pilot orifice correctly. Getting that plate in upside down happens more often than you can imagine.

Regarding the pilot jet size, dont get too hung up on the "correct number" While all my buddies were running 45s and 48's and having all sorts of hanging idle and weird throttle response issues on our CRF's and YZ's, I was running a 40, and stock is a 42. My bike fires first or second kick, hot or cold. 

First things first, make sure the carb is assembled correctly and the float height is correct. It probably wouldn't hurt to check the valve lash and make sure that's in the ball park too.

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3 hours ago, Shawn_Mc said:

First thing you need to do is pull it and make sure it's assembled correctly and the float level is correctly set at 8mm. The level of the float should be set when the valve closes, but that little spring loaded pin is still extended. If you turn the car upside down, the float weighs enough to collapse that pin and the level ends up way way low.

Make sure the vacuum release plate is correctly oriented also. If that's upside down, and the seal is incorrectly set, it's never going to idle and draft over the pilot orifice correctly. Getting that plate in upside down happens more often than you can imagine.

Regarding the pilot jet size, dont get too hung up on the "correct number" While all my buddies were running 45s and 48's and having all sorts of hanging idle and weird throttle response issues on our CRF's and YZ's, I was running a 40, and stock is a 42. My bike fires first or second kick, hot or cold. 

First things first, make sure the carb is assembled correctly and the float height is correct. It probably wouldn't hurt to check the valve lash and make sure that's in the ball park too.

Allright thanks allot really helpful tips, you have any tips on setting the float level? 

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16 minutes ago, Drz400nlm1990 said:

Allright thanks allot really helpful tips, you have any tips on setting the float level? 

When I set them, I roll them over on their side just far enough to get the float to move up, and put a piece of hose on the fuel nipple and blow through it to make sure the needle is seating and not leaking when it'd closed. You can make yourself a float gauge out of cardboard from a cereal box. Just cut a U in it, wide enough to straddle the float where the bowl seats, pass it beneath and close the float up.

This is how the vacuum release plate should be oriented. The seal should be set on the plate so that the flat side of the seal is against the flat side of the plate and the seal reaches out. I hope that makes sense.

 

Vacuum release plate.PNG

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25 minutes ago, Shawn_Mc said:

When I set them, I roll them over on their side just far enough to get the float to move up, and put a piece of hose on the fuel nipple and blow through it to make sure the needle is seating and not leaking when it'd closed. You can make yourself a float gauge out of cardboard from a cereal box. Just cut a U in it, wide enough to straddle the float where the bowl seats, pass it beneath and close the float up.

This is how the vacuum release plate should be oriented. The seal should be set on the plate so that the flat side of the seal is against the flat side of the plate and the seal reaches out. I hope that makes sense.

 

Vacuum release plate.PNG

Thank you very much will be looking into that soon

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I'm going to predict that needle and 8mm float level roll coal at 1/8 throttle. It was an utter mess when I tired it. My solution was a 40 pilot and a rich screw setting, forget how far it was out, and a tick over 9mm float level. On the contrary my bike ran fine with a EMR needle and 45 pilot prior to purchasing the kit. Keep in mind, this was a fresh FCR-MX that I purchased from this site. When I sold my 39 I sent the JD needles along with a few Keihins, I had no further use for them.

 

Regardless of what speed the engine is idling at, if the slide is up high enough the fuel screw is not going to kill the engine. The engine is drawing fuel from the main nozzle/needle if the slide is open too far.

 

 

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1 hour ago, ohiodrz400sm said:

I'm going to predict that needle and 8mm float level roll coal at 1/8 throttle. It was an utter mess when I tired it. My solution was a 40 pilot and a rich screw setting, forget how far it was out, and a tick over 9mm float level. On the contrary my bike ran fine with a EMR needle and 45 pilot prior to purchasing the kit. Keep in mind, this was a fresh FCR-MX that I purchased from this site. When I sold my 39 I sent the JD needles along with a few Keihins, I had no further use for them.

 

Regardless of what speed the engine is idling at, if the slide is up high enough the fuel screw is not going to kill the engine. The engine is drawing fuel from the main nozzle/needle if the slide is open too far.

 

 

True, what could cause the slide to be open too far?

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True, what could cause the slide to be open too far?

The idle adjustment screw. For whatever reason the throttle could be open further to get a good idle than would normally be required otherwise. I can't remember the baseline setting of the slide height from completely closed. 3mm sticks in my mind but dont know for sure.

 

Check the plate, float level, air passages and go from there. If you're still scratching for head buy a EMR needle for JetRUs for around $15. The smaller a pilot jet, the easier they clog. I understand you paid big money for those JD needles but they are not worth it for this application imo. There are more than enough Keihin and OEM needles to select from. For the stock DRZ carburetor it is another story because its needle is not adjustable and nobody has figured out a suitable OEM replacement

 

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49 minutes ago, ohiodrz400sm said:

The idle adjustment screw. For whatever reason the throttle could be open further to get a good idle than would normally be required otherwise. I can't remember the baseline setting of the slide height from completely closed. 3mm sticks in my mind but dont know for sure.

 

Check the plate, float level, air passages and go from there. If you're still scratching for head buy a EMR needle for JetRUs for around $15. The smaller a pilot jet, the easier they clog. I understand you paid big money for those JD needles but they are not worth it for this application imo. There are more than enough Keihin and OEM needles to select from. For the stock DRZ carburetor it is another story because its needle is not adjustable and nobody has figured out a suitable OEM replacement

 

That idle adjustment is hard to get right, and cant see anywere how to adjust the slide height, strange .

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6 hours ago, ohiodrz400sm said:

The idle adjustment screw. For whatever reason the throttle could be open further to get a good idle than would normally be required otherwise. I can't remember the baseline setting of the slide height from completely closed. 3mm sticks in my mind but dont know for sure.

I've seen 1mm as the throttle slide gap, both here and on some KTM forums. The link also has a good "hanging idle" checklist.

Edited by ktmenvy

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After a complete disassembly, Ive always set the idle speed screw (slide stop) at 2 turns from completely closed. The fuel screws I'll set at 1 1/2 turns out, air screws at 2 out, if it has an air screw.

The slide being open too far is kind of a bizarre condition. You really shouldn't be pulling fuel past the needle until about 1/4 ish throttle. If you are, Id be looking at the needle for wear or the needle jet for wear.

When setting the idle mixture on an FCR, you need to set the idle speed to as close to the OEM spec as you can with the idle speed screw, and with a fully warmed up engine, dial in the fuel screw setting until the idle speed is at its highest point. That speed could be double the original idle speed or more, depending on how far out the fuel screw is. Once that's done, reset the idle speed with the idle speed screw. If it burbles on deceleration a 1/4 turn out on the fuel screw should cure it, assuming the fuel screw ultimately ended up some where between 1 and 2 turns out, assuming the pilot and PAJ are correct. Most FCRs come with a 100 PAJ in them, but that's tied mostly to the assumed application of aggressive cam shafts that dont produce a ton of vacuum. If you're chasing a popping on deceleration condition or some weird unhappy idle condition, inability to achieve a setting that makes sense, you might be fighting a mismatch on the primary air jet. Jets-R-Us has a physical description page. Not all the air jets in the FCR-MX's are the same size. But a 100 size hole is the same regardless of the physical config of that style jet.

 

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On 11/13/2019 at 2:21 PM, Shawn_Mc said:

After a complete disassembly, Ive always set the idle speed screw (slide stop) at 2 turns from completely closed. The fuel screws I'll set at 1 1/2 turns out, air screws at 2 out, if it has an air screw.

The slide being open too far is kind of a bizarre condition. You really shouldn't be pulling fuel past the needle until about 1/4 ish throttle. If you are, Id be looking at the needle for wear or the needle jet for wear.

When setting the idle mixture on an FCR, you need to set the idle speed to as close to the OEM spec as you can with the idle speed screw, and with a fully warmed up engine, dial in the fuel screw setting until the idle speed is at its highest point. That speed could be double the original idle speed or more, depending on how far out the fuel screw is. Once that's done, reset the idle speed with the idle speed screw. If it burbles on deceleration a 1/4 turn out on the fuel screw should cure it, assuming the fuel screw ultimately ended up some where between 1 and 2 turns out, assuming the pilot and PAJ are correct. Most FCRs come with a 100 PAJ in them, but that's tied mostly to the assumed application of aggressive cam shafts that dont produce a ton of vacuum. If you're chasing a popping on deceleration condition or some weird unhappy idle condition, inability to achieve a setting that makes sense, you might be fighting a mismatch on the primary air jet. Jets-R-Us has a physical description page. Not all the air jets in the FCR-MX's are the same size. But a 100 size hole is the same regardless of the physical config of that style jet.

 

Where is the fuel screw, air screw and idle screw on the fcr39 mx? Anybody have a picture or diagram that is labeles, sort of getting confused witg the air screw and idle screw. I know where the fuel screw is but my idle screw seems to be way more then 2 1/2 turns out , it looks like its 6 or 7 turns out

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1 hour ago, Drz400nlm1990 said:

Where is the fuel screw, air screw and idle screw on the fcr39 mx? Anybody have a picture or diagram that is labeles, sort of getting confused witg the air screw and idle screw. I know where the fuel screw is but my idle screw seems to be way more then 2 1/2 turns out , it looks like its 6 or 7 turns out

The idle screw is the big one on the left (non-throttle) side of the carb [90]. The fuel screw is on the bottom [32]. The air jets are on the lip of the air intake, inside the boot [30, 103].

fcrmx_parts.pdf (1 page) 2019-12-03 04-51-07.png

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5 hours ago, Drz400nlm1990 said:

Where is the fuel screw, air screw and idle screw on the fcr39 mx? Anybody have a picture or diagram that is labeles, sort of getting confused witg the air screw and idle screw. I know where the fuel screw is but my idle screw seems to be way more then 2 1/2 turns out , it looks like its 6 or 7 turns out

The FCR doesn't use an air screw. The only adjustments that are available without changing parts are the fuel screw and the idle speed screw.

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