yz450F, 06-09
(2010 is EFI and engine is different)

Improve throttle response, horsepower and mileage with the world exclusive Factory Pro HDJ Emulsion Tube - AND make better shifting - especially for SM racing where every shift counts. Ok - every shift counts all the time, so it's a kit that improves shifting all the time, no matter where you are riding.

Factory Pro just doesn't do off road jet kits - we've developed over 300 different jet kits and jetted literally 1000's of bikes - from AMA Pro races to local off road champions to the guys down the street with the Harley.

**True Rear Wheel HP tm**

Keihin FCR
emulsion tubes

by F Pro

Factory Pro's HDJ emulsion tubes for mx type, original equipment FCR carbs.
Aftermarket horizontal  FCR carbs

also avail
Downdraft  FCR carbs
Replaces the original  worn, overrich FCR emulsion tube. Makes more power and improves throttle response.

On a test yz250f, we gained 5% to 7% hp at peak and better part throttle.

The FCR secret.

FCR emu tubes

28, 31, 33, 35, 37,39,41mm

for HORIZONTAL mount  fcr

pn: CRZ-EMU-125k / 036

for orig equipment horizontal mx type Keihin FCR carbs
also for  aftermarket horizontal FCR carbs.

$59.95 each

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Keihin FCR Carb Recalibration Kits - patented Factory Pro HDJ style

(sample pic)

pn: CRB-CY45-1.7-RK   $99.95

yz450f 04-09

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800 869-0497

Available through
Zip-Ty Racing

 Dec 3 2007, 08:37 PM

Group: Members
Posts: 7
Joined: 29-October 07
From: Henderson, NV
Member No.: 2277

I picked up a Factory Pro Jet Kit from www.factorypro.com

They are a little pricey but WELL WORTH IT! My buddy highly recommended them and I do too now.

Im not sure about all kits, but on my YFZ450 it was a little more than a simple jet kit. I had to drill my factory MAJ and add another MAJ (Main Air Jet). It was incredible and comes with everything you need. It uses the same jet sizes as the GYTR kit however you dont need as large of jets because of the MAJ modification.



Now with the new, even cleaner running, patented
Gen 2HDJ
Hi Dispersement Emulsion Tube!

This yz450f carb recal kit was designed with as much care and attention to detail as we give to our EC997 dynamometer and test routines, our Shift STAR shift improvement kits, our Billet Engine Covers and all of the other products that the quickest road racers in the USA and World used to collect a total of 9 WERA and F-USA national Championships - along with the Suzuki Cup World Champion, Rob Jensen.

    We've now entered the off-road arena to bring some new, exciting, well proven concepts, such as our easily tuneable "HDJ" style jet kits and several other things that we've picked up along the way.

    One of the improvements was dyne systems design and test routine design - We have been saying for years that inertia dynos were misleading and now, these new "HDJ" carb kits show how much better the EC997 load dynos are than inertia dynos when it comes to developing any performance products. Sounds a bit egotistical? Perhaps it sounds that way - but, I think that we've got quite a few local Norcal racers that we've done FCR fine tuning work for that would agree with us.

We really aren't egotists -  We are just passionate about fine tuning.

Figure better hot starts, better throttle response, less bogging and the Factory Pro bonus - 4% to 7% power improvement, pretty much everywhere

   The Factory Pro HDJ kits, designed by Marc Salvisberg, will run more evenly over a wider temperature and altitude range than any other carb kit and will produce 3% to 8% better power than another carb with the "best main jet" in it, when properly tuned and tested under a real load. This does not mean an inertia dyno - though, power will be better with a dealership level dyno, also.

So - Here's the power - Buy it!   Thanks!    800 869-0497


Marc, First I want to thank you for the quick reply, you guys are the best.

 The '04' yz250f with your kit seemed to make a huge difference from mid throttle to wide open, and same with the '06'

The CRF450r flat out screamed on top. Amazing!

The '08' CRF250r
seemed to make the most improvement in the  mid throttle range, the guy was in a hurry to get to a race and I only made recommended changes with one test ride (for me not enough testing) but I talked to him a cpl. weeks ago and he said it was running great.

I agree with you, I don't know why more mx'ers don't use your kits - they are hands down the
pinnacle in jet kits.......

...... So can you help me out with the '07' Rmz-250, my son is getting faster moving to the intermediates and
needs more power.

Your #1 fan,
Chuck Sheets
05 rmz450 52+ int.

Factory Pro's Shift kit - help prevent missed shifts and damage caused by missed shifts.


SHFT-EVO-Y46-KT   $239.95
06-09 only
(inc y45 star, 2s2 Arm, y26021-0501 spg, no gasket)
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Feed back to

"How's it working? Aug 2012

Yes, works great! It's a must have item.  5th gear used to only last me about a month due to missed shifts, now I'm going on 3 months since my last rebuild.

Jason Moser
Sault Sainte Marie, MI




yz250f wr250f Evo Shift STAR Kit

"99.7%" eliminate missed shifts.

The EVO Shift STAR Upgrade kit will upgrade your bike to the latest, greatest shift action.

Perfect for when you are tired of paying attention to shifting and just want it to shift right. MX. SM, Desert,  trail -

Virtually eliminate missed shifts  - Shifts 5mm to 10ms quicker

Make shifting MUCH quicker and virtually eliminate missed shifts. Helps address missed shifts caused by poor shift detent "star" profile.
Helps prevent shift fork and gear engagement dog damage caused by missed shifts.

The Factory Pro Shift STAR kit is an awesome upgrade for the Yamaha.

Installation: Slightly more complicated than replacing the clutch basket.

No case splitting required.

Installation Instructions - click here


Yamaha Shift Star kit worked awesome!  Not one missed shift all weekend.  Easier to find neutral, too - Which is good because I have to put it in neutral to start it for some reason. Doesn't like to start with the clutch in. With the close ratio tranny, I did a lot of shifting.

Leigh Thomas - Mojave area


Pro Shift Kit



 will fit
yz450f 08-09

(inc F-Pro Microbearing Detent Arm & spring)
2S2-18140-10-00 STOPPER LEVER ASSY and 90508-26021 apring

z95-y26021-0601  F-Pro Shift Spring
replaces 90508-26021 stock spring
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The One, the Only, the Classic

 Pro Shift Kit

Virtually eliminate missed shifts.

SLICK Hybrid Ceramic Microbearing detent arm - almost friction free roller and sturdy F-Pro Shift spring .

Major improvement in reducing missed shifts and improving shift speed.

Takes about an hour to install (right under the clutch basket)

 Factory Pro's
patented HDJ  MAJ installation for crf / wr / yfz
 Keihin FCR carbs

Where's my main air jet and what do I do with that drill bit and tap that came in my Factory Pro HDJ kit for my Keihin FCR carb?

First step is to eliminate the fixed main air jet restriction.
It's about 40mm down the MAJ hole (left picture).

Set your 3mm drill so that it has 45mm to 46mm of drill bit exposed from your drill chuck.
(see right picture)

Remove the stock emulsion tube (that's what the main jet screws into) so that you can clean out the carb well. By only having 45mm to 46mm of the drill bit exposed, it prevents you from drilling too far.

Then, use the supplied tap from our HDJ carb kit, thread the Main Air Jet (aka "MAJ") hole.
You only need to go far enough to be able to thread in the new replaceable jet that we supply.

Clean the hole, of course.

After it's clean, complete the MAJ Modification by installing the supplied Main Air Jet and installing the new Factory Pro HDJ Emulsion Tube.

If you aren't confident in your ability or in your understanding of what you are trying to accomplish - no worry - Call us up or talk to someone locally who has more experience in these matters.
If you are still not sure, see if there's a Factory Pro Tuning Center locally or visit your favorite local dealership or shop and get some help there -

We all have to learn, and usually having an experienced person around makes everything "easy".

This modification is something similar to what we've done in many different carb types over the years, though it might be new to some who haven't used our "1.7-RK" carb kits before.





Absolutely NO carb parts sold in California.

New and improved
Suzuki Teka SFI 2
with new TPS display and "MMT" Memory Module Tuner feature

Finally - Quick, easy, cost effective Suzuki tuning with no expensive "add-on boxes"
Suzuki cruisers and sportbikes

Please click here for more info

Contact Factory Pro
M-F, 9am - 5pm, Pacific time, -7 or -8 GMT

800 869-0497
 USA and Canada

415 883-5620

no fax

Factory Pro
101c Roblar Drive
Novato, CA

If it's
4pm at Factory Pro it's 9am in eastern Australia.

parts information

EC997 dynamometer information

Product Support /Tech SECTION
click here

And most importantly
Restart back at the HOME page and click on the red box in the top left to find the bike that you want parts for...

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