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Another FCR SLant Carb Jetting Question Thread

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I recently aquired a 2003 KLX400r . The previous owner told me it was having minor Carb issues but believed it was sorted out with the help of a friend of his  . Unfortunately it really wasn't but that's fine . 
The problem I found that it had while riding was sorta power deprived and would want to stall when cutting the throttle from high rev . a few days ago I ordered a carb rebuild kit with standard jet's and needle . 
 Today I pulled the carb and found that the AP was prematurely squirting fuel splashing against the slide so I fixed that . Also found that some jets in this carb are not standard but are old and deteriorating .
The bike seems stock with the 3x3 opening in the airbox and a Pro Circuit Slip on but with standard header .
I live in Albuquerque ,New Mexico  and ride with elevation ranging 5k to 7k.
I'm wondering if it would be better to run with standard jets rather then what was installed .
 The current Main Jet is a 145 Stock is 142 and the pilot is a 45 which is stock , has stock needle too and the slow air Jet is a 65 rather than a stock 60 .


 

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3 hours ago, ohiodrz400sm said:

You could likely go up a size or 2 on the main. Needle either stock obx 5th clip or emn on 3rd . Pilot should be close.

Set the float to 9mm while it's apart.

Hmm . Interesting reply . In the past I've ran an overly rich circuit and thought maybe that was the case here . grant it was a different bike "YZ450" but had a FCR as well  .It shared the allot of the same scenario I have with the klx .
Running 5th clip seems a little extreme and going bigger with the jets do too . I really thought that with the "very mild mods" that maybe factory standard jetting would be Ideal  in this altitude . I really dont know any more or remember . Been spoiled with EFI for the 4 years .
 

Edited by xxcody2gunsxx

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Thanks for all the info, getting ready to do the swap on my 2006 SM and need all the help I can get. 

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I'm Stumped . I rebuilt the Carb and decided to go with the oem jets that came with the kit  . feels better BUT still have this idle issue so to speak .
 Here's the scenario . I'm riding on trail 2nd or 3rd gear "it really doesn't matter" I cut the throttle to hit the brakes and it stalls or almost stalls . Okay ... So I increase the Idle and start riding down the trail again . I want to slow down to a oncoming turn Ipull the clutch  release the throttle and now I have a high hanging idle a couple seconds before it calms down to the original idle speed I set .
 
 I have set the float 9mm ,fresh jets , needle etc , Correct AP adjustment , zero air leaks that could find . I decided to check the valve clearance and they are well with in spec . Replaced spark plug and still have the same problem .
 Does anyone have an Idea what this issue might be ?
 

Edited by xxcody2gunsxx

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Yep ,I know the drill .I appreciate it . Been avoiding  the fuel screw as it's next to impossible to reach on this KLX .The  Extended fuel screw I bought and installed ,I had to uninstall due to clearance issues between the starter and the carb . Guess I have to pull the trigger on the R&D flex fuel screw and hope it doesn't have any clearance issues .

Edited by xxcody2gunsxx

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Yep ,I know the drill .I appreciate it . Been avoiding  the fuel screw as it's next to impossible to reach on this KLX .The  Extended fuel screw I bought and installed ,I had to uninstall due to clearance issues between the starter and the carb . Guess I have to pull the trigger on the R&D flex fuel screw and hope it doesn't have any clearance issues .

R&D will fit the slant fine. Attach the knob on the rear screw.

You will probably have to open the hole slightly for it to fit. When I installed one on my old slant I did it by hand with pliers and a drill bit. Not a big deal.

 

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Carburetor is back together with a outlaw AP Cover and a R&D Flex screw . 
 I believe I found the problem too . Setting the Idle and mixture  I am fully closed on the fuel screw and getting a good idle still . If I start backing out the fuel screw the idle drops to the point of stalling out . Guess that means the stock pilot jet is to big and need to go down a size yeah ?

 

DSCF2886.JPG

Edited by xxcody2gunsxx

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Okay so I ordered a 42 Slow jet and I adjusted the TPS according to my feedback of overly rich idle circuitry. still with in perimeters but on the lower side . After a couple loops in the backyard it seems to have more snap ,better power delivery .I am in the right direction .  Before I got the carb back in the bike I did move from the 4th clip position of the needle to the 5th .I'm thinking when I remove the carb to install the smaller Slow jet I'll also set the needle back to the 4th positon .Maybe I'll make a short video of the removal of this carb while I'm at it for anyone who is having doing so .

:thumbsup:

Edited by xxcody2gunsxx

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Okay so I ordered a 42 Slow jet and I adjusted the TPS according to my feedback of overly rich idle circuitry. still with in perimeters but on the lower side . After a couple loops in the backyard it seems to have more snap ,better power delivery .I am in the right direction .  Before I got the carb back in the bike I did move from the 4th clip position of the needle to the 5th .I'm thinking when I remove the carb to install the smaller Slow jet I'll also set the needle back to the 4th positon .Maybe I'll make a short video of the removal of this carb while I'm at it for anyone who is having doing so .


You can remove either with the carburetor in place. The needle is simple. The pilot is a bit of a pain but doable with the correct screw driver

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I think some of the hanging idle and just general idle running has to do with the OB**** needle , whichever one you have . I've now put 3 FCR's in my bikes and all had wierd idle issues , slight hanging idle ect... Going smaller on the pilot only made the bikes harder to start cold , needing 4-5 accel pump squirts and full choke with 10-20sec. cranking to start , yet the mixture screws all needed to be bottomed out for best running . When I put my wideband meter on one it was a real fast change in the mixture ratio going from idle to just over 1/8 throttle . I think those needles are too short and/or tip shape not ideal .Though I can't say I have much experience with these particular carbs.  My DRZ is running good now by switching to the EMN needle , can't remember what groove for the clip .

I had quit carb tuning and had switched to mostly efi toys , still have 2 , I'll take them any day. A laptop or app. and proper software , tune to perfection for changing conditions are so easy and actually fun .

 

.

Edited by jjktmrider

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1 hour ago, ohiodrz400sm said:


You can remove either with the carburetor in place. The needle is simple. The pilot is a bit of a pain but doable with the correct screw driver

Roger that . It'd be easier just to remove the carb all together . doesn't take much thus why I think I'll make a quick video of it .

1 hour ago, jjktmrider said:

I think some of the hanging idle and just general idle running has to do with the OB**** needle , whichever one you have . I've now put 3 FCR's in my bikes and all had wierd idle issues , slight hanging idle ect... Going smaller on the pilot only made the bikes harder to start cold , needing 4-5 accel pump squirts and full choke with 10-20sec. cranking to start , yet the mixture screws all needed to be bottomed out for best running . When I put my wideband meter on one it was a real fast change in the mixture ratio going from idle to just over 1/8 throttle . I think those needles are too short and/or tip shape not ideal .Though I can't say I have much experience with these particular carbs.  My DRZ is running good now by switching to the EMN needle , can't remember what groove for the clip .

I had quit carb tuning and had switched to mostly efi toys , still have 2 , I'll take them any day. A laptop or app. and proper software , tune to perfection for changing conditions are so easy and actually fun .

 

.

That's the needle I'm running with too . I get it with efi as well . I have a 16 rmz450 and a 14 ktm and never have to deal with such prob's BUT I will say with this fcr carb ,every turn in the right direction and seeing come to life feels great . getting close to the response and power I know it has .

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Okay so I'm stumped . went from a 45 slow jet  to a 40 and didn't change a thing . Still idles well with the fuel adjustment screw all the way in and if I screw it out any it starts dropping the idle .

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12 minutes ago, xxcody2gunsxx said:

Okay so I'm stumped . went from a 45 slow jet  to a 40 and didn't change a thing . Still idles well with the fuel adjustment screw all the way in and if I screw it out any it starts dropping the idle .

Not sure on the Slant but I'm having the same issue with my MX, going bigger on the pilot air jet has helped overcome this.

Also try the needle on the 3rd clip.

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11 minutes ago, -=fusion=- said:

 

Not sure on the Slant but I'm having the same issue with my MX, going bigger on the pilot air jet has helped overcome this.

Also try the needle on the 3rd clip.

 The needle clip is currently 3rd position . I was just reading over the manual was thinking about the air jet . I just got done removing the air jet and blowing compressed air though the passage thinking maybe something is plugged there . not sure

7 minutes ago, ohiodrz400sm said:

Turn your idle speed down and try again.

If needle height affects idle then the speed is too fast.

The needle isn't interfering with the idle .  Tried adjusting idle and starting over and over again . The end result always ends with the Fuel crew all the way in and any turns out drop the idle . Trying to get to the other side of the fence where turning it in will drop the idle and turning it out will increase to a point of the correct mixture . So far it seems that its not getting enough air maybe :excuseme:

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Okay so I cleared all passage ways  and problem persisted . I started drilling the diameter of the old air jet I had sitting around .Little by little I have started getting some results .
Thanks -=fusion=- for the Idea of a bigger air jet . I can now turn the fuel screw in and will drop the idle some and also far enough out it will do the same .
 I found that 1-1/4 to 1-1/2 turns out with the fuel adjustment screw is perfect .
 What does that say about the rest of the fuel circuit ? I don't know but I'll see how this feels when I can .For now I'm happy to get the response I should with the fuel adjustment screw .
and thanks ohiodrz400sm for helping me out .

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