MORE HP & TQ & Quicker Response


                                                       Introducing the FC 2000 Series Flo-Commander.

No more "messing" with that little "hard to get to" idle mixture screw. You can simply set it slightly lean then do all the tuning with the easy-to-get-to screw on the left side of the FC. You will have a full range of adjustment with it, even while riding, from full rich to full lean!!!                                                                                                                                                                       

   For your “original style” Aftermarket, OEM original style"MX" OEM style or the aftermarket MX style FCR, four stroke single Keihin Flat Slide carb application, along with replacement FCR Flat Slide Carb Kits for several other models. It is an easy bolt-on replacement which takes no time at all to install.                                                                                                                           

  • An Awesome Performance Boost for your 4-stroke Single application.
  • The Ultimate in Performance Boosting Products for your FCR carb(s)!
  • The Flo-Commander 2000 works great on your FCR Flat Slide Equipped Super Motard or Super Moto
  • Tune your carb without shutting your engine off! 
  • Tune "On-The-Fly" with one of our remote controls!   
  • Approx. a  2 - 3 Jet size span of adjustment on both main & pilot circuit.
  • We have made some new minor changes that make attaching the remote control cable end to the right side needle easier yet, with the boot clearance being very tight before. The new needles also have a longer grip section which also makes attaching the Cable end "Bell" very easy to do, when a remote is used. The longer grip section also makes it easier to grip & rotate. We still machine the concave slots in as well.  

           HUSABERG Models will be listed shortly along with more Husky Models       

  •                                                                                                                   THE NEW 63 MM MONSTER!

     It won't Increase Performance in just part of the power curve, it WILL increase performance OVER THE ENTIRE CURVE.


          Designed for the “FCR Flat Slide” models w/the removable Air Filter Adapters, or Velocity Stacks.                                                            

What all they fit on, or apply to;

OEM YZF 400, OEM YZF 426, FCR Replacement Carbs for several models, in other words when you have installed a FCR carb/kit, made to replace an original carb. Those models are shown below. Also, any original design FCR Flat Slide, 35 MM to 41MM.

                                                  See the installation pics at the bottom of this page.

                                        Scroll to the bottom of this page for specific info on the DRZ 400


Steve, I just wanted to say thanks again... I bought this item as a complete novice and you walked me totally through proper jetting.  This absolutely rips!  3rd gear power wheelies on command!  No more stumbles, or surging.  Just nice, smooth acceleration.  It makes a nice addition on the FCR MX.

Also your customer service is absolutely out of this world, I wish other business' would take notice.



                                                                 How it works, & why;

  The FC 2000 re-routes the air-flow for the air-jets, from the path of pressure variances & turbulences that it did take, to a much smoother more calibrated & controlled flow to the carb`s Pilot & Main Air-Circuits. It also greatly smoothens the air-flow directly into the carbs main throat. On top of all that, you get instant adjustability to the main & pilot circuits. No disassembly of any kind of the carb to make a adequate amount of adjustability to the fuel/air mixture. 

 If you totally understand carburetor circuitry & function, & the significance of the above, there's no need to read the following section. If you still aren't sure about it, & would like some very valuable information, take a minute or two & read it. Then, re-read or think about the top few sentences & it will all become very apparent why it works so well. I only barley break the surface of fuel/air induction below, but explain enough to make the FC make very good sense. 


As with all factory produced carbs, they put the air-jets or bleeds, where it's most convenient for production purposes, (cost & simplicity) & for keeping things simple, & where they don't need to do much design work, to at least make things work decent, not the way they will work the best. I'm speaking here mainly the FCR Flat-Slide, although the other type FC, (the 1000 Series FC) solves many of the same air-circuit problems, just in a different way on the many other type carburetors out there. The entrance to the air-circuit is extremely important, and for too long everyone in the industry has neglected to delve into the induction properties of the air-circuits. Therefore everyone has been ignorant to what could be accomplished, if the air/fuel circuits were actually re-designed or corrected if you wish. Anyone who truly understands carburetor basics, knows the circuitry has always needed extra help when the throttle is worked thru its different positions. Throttle position is what controls which circuit(s) are working at any particular time, & to what extent.  RPM is a by-product of throttle position which then also helps determines how much air is allowed to flow thru the throat, choke-down or venturi area of the carb then into the engine.  

  Anything (to a certain degree) that is done to smoothen the air-flow into the carb throat, and into the air-jets helps the carb "make sense" of whats going on & what it's supposed to do. This is one reason in recent years the manufactures at least started taking the air-jets out of the path of the air going into the carb throat. They found that when they separated the air pressure & flow going into the carb from the air-jet, the impulsion tube (or needle jet) & the jet needle could then do its job much easier, as the air being drawn into the air-circuit was much more linear thus easier to calibrate with the rest of the circuit. Proof that the issue of space, production costs, & simplicity are even still an issue, is the fact that many side draft carbs on multi cylinder engines, and most oem single carb`d bikes, are still equipped with the outdated circuit technology. As long as the factories can get away with it though, they will keep saving the R&D & manufacturing costs & leave it alone. Whats so comical though is how many misconceptions the general public still has about fuel injection. The reason so many bikes went to fuel injection, is definitely not for the reasons they and all the magazine editors want you to think. The proof of that is the fact that a good working/calibrated carb that is the right size & design for where its being used cannot be outperformed by the typical fuel injection system, many times, even if it is re-mapped. There is several areas of operation in which even brand new fuel injection systems still have problems. They may not be real obvious to the armature tuner, or rider, but they are definitely there. In fuel injections defense it does pollute less, from the factory anyway, (hint hint), but, its at the expense of lower rpm & lower throttle plate opening performance, although it is getting better! Another issue   with fuel injection is ease-of-adjustability (or lack thereof) & the complexity of it all to the average rider, compared to simple carb adjustments that almost anyone can do, & without a computer or dyno!  


                                                               FC-2000  simple specific explanation.  

   Using the YZ-F 400 & 426 stock adapters compared to ours as an example, our units will flow 18+%  more total air flow, due to it's shape & contour but just as importantly, not only without losing velocity, but actually increasing velocity. Along with that, you have the convenience of quick air/fuel adjustments of both the pilot & main air circuits, without even shutting off the engine!! This means more track time and much less tuning time.
  The Flo-Commander 2000 series units will shine even more when you do other mods to the engine and or exhaust!! Just by installing one of these, you will add several HP, more TQ, and pick up the throttle response as well, especially with a good aftermarket pipe, as they will allow the better pipe to pull even more air/fuel thru the engine, for maximum performance!! No mods to the carbs themselves are necessary at all. You will pick up clean air for the carb circuits, from the air-box or remote filter, depending on your set-up. You have the option of going into the air-box thru a grommet, or the remote filter for Road Racing, Street, or light Off Road use. In mud, heavy dust and water, the air-box method is recommended. They will be available in several inlet sizes for a wide variety of applications!

All systems - $149.95  

                   A 63mm FC 2000 with the second generation needles  450.JPG (46484 bytes)

                                                                                                                              A 63 mm FC 2000 with our second generation needles.

Included w/the Kit
  All kits include all necessary hardware to install with an air-box. Shown here is a typical kit w/ the completely pre assembled main unit, with SS mounting screws, Military Spec air-box grommet, special O-Rings, ball end "Allen" wrench, and tubing. If you are running a single aftermarket "Pod" type filter, you need to get the Remote Filter Kit at the bottom of this page, or you can plumb into the end cap of the Pod Filter.  All components are compatible with all race fuels including alcohol, and Nitro. We now include a composite 90 deg elbow, that will allow you to go back but clear a Pod Filter, or just to just head straight back to the air-box etc. You can shorten the end that presses up onto the SS inlet if you want, to bring the tubing up closer to the rubber inlet tube or pod filter, if you have the clearance space, or whatever other reason you may have. You get Stainless Steel Screws, along with all parts on the Aircraft Aluminum main unit being, Stainless Steel or brass. Even the springs we manufacture for all our FC`s are made from Stainless. There is an extra spacer & O-ring so the same FC-2000 system will fit on the high pilot air-jet standoff, or the low one. In other words, any FCR original, or MX Version. It does not fit the OEM carbs that the air-inlet adapter is integral to the carb, as on the CRF450, YZ450F, etc. It will fit the better performing, lighter FCR replacement carbs though for these same bikes, or the OEM FCR carbs, that are the original or MX style.  

Also included are decals & easy to follow instructions with high resolution color photos                        

                                                          Below is the OEM "Smog Monster" FCR carb.                                     



                                                                                                                                                                                    Above, flow testing with a Suzuki DRZ 400 boot, (an "E" boot here).


 HUSABERG Models will be listed shortly along with more Husky Models 

Applications & part numbers

We have now made some changes as far as fitment goes. We have added a small port spacer & o-ring to all the systems so the user can use it if the carb needs it it & not use it if not needed. There are two FCR carb configurations. One has an extended ht. pedestal under the pilot air-jet, one does not. The o-ring & spacer allows the same FC-2000 to be used with either carb. This way if someone has switched the original FCR carb to the other style on your machine, say, before you obtained it, it won't matter. Also this eliminates the need for universal kits. You simply purchase the FC-2000 that has the proper neck size for your application if not listed. Having said this, it's no problem and causes no adverse effects in performance if you install a FC that is up to a couple mm under sized or even slightly over than your boot size, if you happen to not find a FC-2000 that is perfectly the correct size. 

       Call 334-693-9203   or e-mail info@performance-design.net if you have any application, tech, or etc questions.

We are now doing all the FC-2000s in a deep red, unless special ordered. This prevents the confusion by some, of why some were blue & some red. All the new models have been lightened in the main body, but still are dimensionally the the same as far as the neck sizes & bores. 

 FC-2000 with 54 mm neck size.
  • YZF 400 all
    DRZ 400 Suzuki w/ OEM FCR 39mm Formerly FC-21251
    PART# FC-21255 $149.95
  • YZF 426 all Formally FC-21252
    PART # FC-21255 $149.95
  • Order Page
    Shown to the left is our new 54 mm unit, on a carb that we have coated with our Pro-Gold Heat Barrier

 FC-2000 with 57 mm neck size.
  • XR 600 88 – 99 W/Repl. Flat Slide 

  • TRX 400 all quad W/Repl. Flat Slide 

         was Formally FC-22501


 FC-2000 with 60mm neck size.
  • XR 650L 93 – 99 W/Repl. Flat Slide 
  • DRZ 400 all W/Repl. Flat Slide
  • KLX 250 all W/Repl. Flat Slide
  • LTZ 400 all quad W/Repl. Flat Slide 
  • KFX 400 all quad W/Repl. Flat Slide 
  • Arctic Cat 400 quad W/Repl Flat Slide
  • Formally Part # 23751
  • PART # FC-23755 $149.95

               Order Page




 FC-2000 with 63 mm neck size.           PART # FC-25005 $149.95

                Order Page

XR 650R Honda W/FCR Replacement Carb

TRX 450 Quad W/FCR Replacement Carb


2004 SMR 630 

2005 TC 250, 450, 510

2005 TE 250, 450, 510

2005 SMR 450, 510                   

2006 TC 250, 450, 510

2006 TE 250, 450, 510

2006 TE 610

2006 SM 610

2007 TE 250, 450, 510

2007 TC 250, 450, 510

2007 SMR 450, 510, 

2007 SM 610

2007 TE 610

More to be added!

The  SMR 630, & the  TE, & SM, 610   models    (need to use a remote to access right adjustment) We have a special screw when using the FC on this particular Husky model, as the Right side screw is blocked by the wrap-around type inlet tube.

  KTM with OEM FCR`s  & with the aftermarket FCRs as well.


2000    400 SX Racing USA ,   400 SX Racing DIV,   400 EXC Racing DIV,    520 SX Racing USA,    520 SX Racing DIV,    520 EXC Racing DIV,    520 EXC Racing Aus,    520 EXC Racing USA

2001    400 SX Racing 400,   EXC Racing Six-Days EU,   520 SX Racing,  520 EXC Racing Six Days EU,   520 EXC Racing EU,    520 EXC Racing  AUS,    520 MX Racing USA,   520 EXC Racing USA,   540 SXS Racing,   

2002    520 SX Racing,    520 EXC Racing Six Days EU,    520 EXC Racing EU,    520 EXC Racing AUS,    MXC Racing USA,   20 EXC Racing USA,    520 EXC-G Racing USA,    625 SC EU,    625 SC SUPER-MOTO EU,

2003   250,    400 EXC Racing Six Days EU,    450 MXC,   450 EXC,   450 SX,   525 MXC,   525 EXC,   525 SX,   625 SXC,  625 EU,    660 SC,   660 Super-Moto Factory Rep D,  660 Rallye

2004  250 EXC Racing,   250 Enduro EXC Racing,   250 EXC Racing GB,   250 EXC EU,   250 EXC Racing Australia,   400 EXC Race,   450 EXC,   450 SX,   450 MXC Race,   520 SX,   525 MXC Race,   525 MX Dessert,   525 EXC,

2005  250 EXC,   400 EXC,   400 SMR,   425 SX Race,   425 MXC Race,   450 MXC,    450 SX Race,   450 EXC Racing,   500 EXC,   525 MXC, 525 MXC Desert Racing,   525 EXC,   525 EXC Racing,   525 SMR,   525 SX Racing,   625 SMC,

2006   250 SX-F,   250 EXC Racing,   400 EXC Racing,   400 EXC-G Racing,   450 XC-G Racing,   450 EXC-G Racing,   450 SMC USA,      450 SMR,   450 EXC Racing,   450 SX,   525 XC-G,   525 EXC-G Racing,   525 EXC Racing,   525 XC Desert Racing,   525 SMC USA,       525 SX,   560 SMR,   625 SXC,   660 SMC,

2007  250 SX-F,  450 SX-F,  450EXC-G Racing,  525 EXC-G Racing,  250 XCF-W,  450 XC-G Racing,  525 XC-G Racing,  450 SMR,  560 SMR


2003 FS 400C

2004 FC 450,  FC 550,  FE 501E,  FS 650S

2005 FC 450,  FC 550,  FE 450E,  FE  550E,  FE 650E,  FS 450C,  FS 450E,  FS 650C,  FS 650C

2006 FE 450E,  FS 450E,  FE 550E,  FE 650E,  

2007 FS 550E,  FE 450E,  FE 550E, FS 650E, FE 650E,  FS 650C

Its currently recommended to run a remote filter on the Husabergs, due to the short snorkel & integral air-box design. The snorkel does not have a convenient location to plumb into where there is fairly "calm" air to pick up. 








Our Flo-C 2000 next to an OEM KTM FCR adapter . With our circuitry design we eliminate the turbulent feed passages leading to the air-jets, allowing for an immensely more controlled metering system along with allowing for proper shaping for high velocity along with high flow!

The ID & OD of the neck size are identical, but it doesn't take any engineering experience at all to plainly see which is going to have smoother & more air-flow. If a picture speaks a thousand words, this is definitely one of them!












Flow testing a Husqvarna Airbox & Flo-Commander 2000


  • Remote filter
    PART #FC-2RF1 $21.99
  •                                        Order Page


To the left, simply unbolt carb with the special Ball End Hex Wrench ("Allen Wrench"), & move it to the side. Then remove the old spacer, both air-jets & install the FC with the provided O-Rings & new SS Screws, (to the right).  Attach the included tubing from the bottom of the FC to the air-box or to the remote filter, (whichever way you choose to do it). Good instructions included. Now you are set to fine tune, & it's very simple to do. Now you can enjoy the new added performance your engine will have.

                  Order the Remote Filter separately if you want to do the install that way, it's explained in detail above.


A heat barrier coated FC 2000 & a normally coated FC 2000.JPG (72295 bytes)

A special heat barrier coated FC2000 & a normally coated FC 2000.

We can for an added fee coat one for you with the heat barrier or coat

one you already have. Contact us with any questions.


   The DRZ 400 carb style facts


Here is a good list of the DRZ Models, & which carb & inlet neck they have from the factory. 

Models for the 

Suzuki DRZ400

DRZ400 K1 has an OEM FCR

DRZ400Y has an OEM FCR

DRZ400EY has an OEM FCR

DRZ400SY has an OEM Mikuni

DRZ400 K1 has an OEM FCR

DRZ400E K1 has an OEM FCR

DRZ400S K1 has an OEM Mikuni

DRZ400 K2 has an OEM FCR

DRZ400E K2 has an OEM FCR

DRZ400S K2 has an OEM Mikuni

DRZ400E K3 has an OEM FCR

DRZ400E K4 has an OEM FCR

DRZ400E K4 E-33 (Ca. Model) has an OEM Mikuni

DRZ400S has an OEM Mikuni

DRZ400SM has an OEM Mikuni


Here are the facts on the inlet Snorkel, ("tubes"/"boots") .

  The inlet snorkel for the models that original had the Mikuni carb, have a very large dia.,  60mm neck ID. The models that originally had the factory FCR, have a more reasonable , 54mm dia. ID neck. The issue here is that when you go to a mechanically operated carb, like when you remove of the Mikuni & install an aftermarket FCR, the neck size, can actually be too large for the best performance. The reason is that you will generally open the carb slide a little quicker than that much area can flow smoothly. The  larger the area in the tube, the slower the air moves. When you snap the throttle open to quick, the air isn't flowing straight, smooth or with enough velocity & the engine can bog slightly, even if you don't feel it. The exception to this is when you have heavily modified your engine, (internally) & it flows a lot more air than one will with just a pipe & free flow filter etc. Since the OEM Mikuni has a vacuum operated slide, it doesn't open faster than it should, no matter how quick you open the throttle. 

  The answer we discovered is to get a snorkel, for a model that had an original FCR & put it on your machine. They easily interchange. You should then, with a long razor type knife or a die grinder with a course cutter, cut all the access rubber out of the bottom of the smaller snorkels for max air flow. The reason its there is the OEM FCR Adapter that connects the carb to the snorkel has ports that must be in the way of good max air-flow. Our design removes this port arrangement allowing much better & more even air flow. So, you can then open the snorkel to match. Its actually quite simple. But you don't have to remove it, if you choose not to, but it work work even better if you do.

  If you have a large snorkel though & would rather not change it, you simply get the FC 2000 that we list for it. Since the FC2000 makes the circuitry work so much better, & smoothens & increases air flow, you won't have quite the bog issues that you can get if you use the adapter that comes with your new aftermarket FCR. Theres nothing wrong with the adapter that comes with the aftermarket FCR, its simply made to be a simple bolt up, so, it has to be that large. 

  We now stock the smaller ID snorkels as we've had so many requests to get them for folks, just ask when you order your FC2000. 





FCR Parts