Need help with jetting/ tuning my 39mm FCR Slant Body carb

[WhiskersFox]

Hello all, I have a 2008 DRZ400sm that I bought a few months ago.  It has 3x3 mod, FMF Q4 muffler, 39mm FCR Slant-Body Carb.  I bought the FMF Powerbomb header to match the exhaust.  I decided to take my carb off and clean it while changing header and see what is in there.  I am somewhat new to carbs so there are a few things I am trying to figure out.  From what I see, I have a DXP needle, 165 main jet, 45 pilot jet, 200 main air, and 65 pilot air(?).  All jets are the Keihin jets.  So, I have a few questions, which I will address with what I know and have been told.  Also just listing my plan so please advise if something sounds wrong.

1.  It was running a little rich before so I am jumping down to a 160 but also getting a 162 if I want to go back up a bit.  

2.  Leaving the pilot jet at 45 (seems to be the recommended size for having these mods)

3.  Leaving the main air at 200 (also recommended)

4.  Not sure what the deal is with the pilot air jet.  Not even positive that is what this jet is but went with process of elimination.  I am referring to the jet to the right of the main jet in my image.  Most things I saw recommended a 100 pilot air, but I also saw a different post saying the pilot air depends on weather or not you have removed the coast enricher (which I have not).  Any advice here would be greatly appreciated.  Current size is 65.

5.  My friend recommended a EMN needle which it looks like a lot of other people use as well.  So I was probably going to do that.  

6.  Also ordered the "R&D flex-jet" extended mixture screw.  Was going to start around 2.25 turns and go from there. 

 

That is all the stuff I have going on.  Hopefully some of you more knowledgable people can help me out or provide some info. 

Thanks!!!! 

[JLCrawford]

Hello all, I have a 2008 DRZ400sm that I bought a few months ago.  It has 3x3 mod, FMF Q4 muffler, 39mm FCR Slant-Body Carb.  I bought the FMF Powerbomb header to match the exhaust.  I decided to take my carb off and clean it while changing header and see what is in there.  I am somewhat new to carbs so there are a few things I am trying to figure out.  From what I see, I have a DXP needle, 165 main jet, 45 pilot jet, 200 main air, and 65 pilot air(?).  All jets are the Keihin jets.  So, I have a few questions, which I will address with what I know and have been told.  Also just listing my plan so please advise if something sounds wrong.
1.  It was running a little rich before so I am jumping down to a 160 but also getting a 162 if I want to go back up a bit.  
2.  Leaving the pilot jet at 45 (seems to be the recommended size for having these mods)
3.  Leaving the main air at 200 (also recommended)
4.  Not sure what the deal is with the pilot air jet.  Not even positive that is what this jet is but went with process of elimination.  I am referring to the jet to the right of the main jet in my image.  Most things I saw recommended a 100 pilot air, but I also saw a different post saying the pilot air depends on weather or not you have removed the coast enricher (which I have not).  Any advice here would be greatly appreciated.  Current size is 65.
5.  My friend recommended a EMN needle which it looks like a lot of other people use as well.  So I was probably going to do that.  
6.  Also ordered the "R&D flex-jet" extended mixture screw.  Was going to start around 2.25 turns and go from there. 
 
That is all the stuff I have going on.  Hopefully some of you more knowledgable people can help me out or provide some info. 
Thanks!!!! 

What is the complaint for changing the jetting Whiskersfox?

[WhiskersFox]

46 minutes ago, JLCrawford said:

1 hour ago, WhiskersFox said:

 

What is the complaint for changing the jetting Whiskersfox?

Not so much a complaint.  I was just told that changing from stock header to aftermarket will require some re-tuning of the carb.  I certainly can just leave everything in there and try it out after I put the header on.  So, trying to understand more about carbs in general AND asking if there is any specific advice or other inputs for the setup/ potential setup.  

[JLCrawford]

Not so much a complaint.  I was just told that changing from stock header to aftermarket will require some re-tuning of the carb.  I certainly can just leave everything in there and try it out after I put the header on.  So, trying to understand more about carbs in general AND asking if there is any specific advice or other inputs for the setup/ potential setup.  

I have the exact same set up as you do, other than I believe mine has the hot cams, (I was told when I bought it), and I live in Kansas and have ridden in Arkansas with no fueling problems, after much tinkering with my carb, this is what I have come up with,....main jet 160, pilot 48, needle EMN position 3. Fuel screw is very sensitive so I play with it, start at 2 1/2 and turn in til engine speeds up then back out 1/4 to 1/2 turn to keep from back fire under deceleration. If you have to use the choke a little for warm up it is about right, otherwise it will be too rich at idle when warm.

[WhiskersFox]

 

1 minute ago, JLCrawford said:

I have the exact same set up as you do, other than I believe mine has the hot cams, (I was told when I bought it), and I live in Kansas and have ridden in Arkansas with no fueling problems, after much tinkering with my carb, this is what I have come up with,....main jet 160, pilot 48, needle EMN position 3. Fuel screw is very sensitive so I play with it, start at 2 1/2 and turn in til engine speeds up then back out 1/4 to 1/2 turn to keep from back fire under deceleration. If you have to use the choke a little for warm up it is about right, otherwise it will be too rich at idle when warm.

Cool, so I will probably go with that.  Any knowledge on the pilot air?  

[JLCrawford]

I have the exact same set up as you do, other than I believe mine has the hot cams, (I was told when I bought it), and I live in Kansas and have ridden in Arkansas with no fueling problems, after much tinkering with my carb, this is what I have come up with,....main jet 160, pilot 48, needle EMN position 3. Fuel screw is very sensitive so I play with it, start at 2 1/2 and turn in til engine speeds up then back out 1/4 to 1/2 turn to keep from back fire under deceleration. If you have to use the choke a little for warm up it is about right, otherwise it will be too rich at idle when warm.

Also, I left all the air jets alone but not sure if previous owner had changed, if I remember correctly I double checked them that air jets were std. as carb was shipped. The needle grooves are counted 1 being top so third groove down from top.

[JLCrawford]

Also, I left all the air jets alone but not sure if previous owner had changed, if I remember correctly I double checked them that air jets were std. as carb was shipped. The needle grooves are counted 1 being top so third groove down from top.

Pilot air screw 1 turn out.

Pilot air screw 1 turn out.

[JLCrawford]

Looks like pilot air jet 100, main air jet 200, from a post I saved. I also moved needle to position 4 from top EMN needle, sorry for the reposts but did some digging to find info, looks like last time I did any changes was July of 2014, so it has been working great since, some hiway miles at 70mph. short hauls back and forth to work, and trail riding several days at a time. Good luck, don't get too lean on main jet or bad things happen, check your spark plug, it should be light brown. Black too rich, white too lean.

[30x26]

65 is the starter jet , it works when you start the bike with pulled choke. pilot air jet is in the intake bell of the carb. at the moment you do not need to change it because form your photo it seems that you still have the air cut valve installed.

stock unkorked bike was 165 - 45 - dxp at 4th clip - ACV installed

these were the suggested setups with fcr slant body:

first step:  move the needle at 5th and pilot screw at 2.5 (48 pilot may be necessary at low elevation/ cold climate)

second step: install EMN-EMM at 3rd/4th clip and 155 main jet, 45 pilot at about 2 turns