Road Test:, ex250 test


Kawasaki EX250, GPX250r

Great in-town bike and a fun entry level racebike for areas of the world that have a 250 Production race class.

Little known fact - Factory Pro has built quite a few race winning EX250 racebikes. Porting, milling, boring, Full Radius Valve Jobs were available for the 250. We specialize in custom tuning the EX's - whether we built the bike or not.

To extract the maximum power for the engine, it is necessary to use the Low Inertia EC997 Tuning Dynamometer with 4 Gas EGA to concurrently dial in the carbs and the cam timing. You can't really do optimum work on an inertia dyno, socalled "tuning to an af as is usually found at dealerships levels -


EX250 during oil additive testing on EC997 Eddy Current Dynamometer by Factory Pro

F-Pro Shift Spring  -  Shift quicker and virtually eliminate missed shifts

The Blue Magic Shift Spring

$20 + shipping
(yes, in good humor, it's $14 for UPS Ground, even for a little blue spring - and we have to ship it tracked and insured. I can't just drop it in the mail and hope and wish you get it and no, I can't send someone down to the post office to mail it Priority tracked and insured)
You could pretend it's:

$32 and Free UPS ground shipping!
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Talked to a guy who said this spring worked really well. Actually said he cut over a second from his lap times just because he didn't have to worry about missed shifts anymore. He said he told all his friends to get one.
Leigh Thomas / Factory Pro
Feb 2015

The originator of motorcycle shift kits.

Blue Shift Spring

Guys be like "When you gonna make a 250 Shift Spring?"

Find Neutral easier - (ok, n is pretty easy to find on a Kaw :-)
Improve lazy shifting.
virtually eliminate missed shifts.
virtually eliminate false neutrals.
help prevent gearbox damage caused by missed shifts.

Countless hours of thought went into this spring's specs.

"The Blue Magic spring"


Positive feedback rating

This kit includes the new F-Pro Shift Spring.
That's it. A carefully fabricated and heat treated spring.

1-2 minutes to install.

1. Remove bolt and old spring.
2. Replace old spring with New Blue Shift Spring.
3. Replace bolt.
4. Shift better and find neutral easier.

Clutch Throwout Bearing
8 ABEC-7 Skateboard Bearings:Nylon Cage:Open: Bearings And ...

Low Friction
Mini Hybrid Ceramic

Clutch Throwout Bearing


1 bearing kit

pn: BE-HYCER-K0067
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Hybrid Ceramic Throwout Bearing

Decrease Friction.

Unwanted friction is the enemy of  good and quick shifting.

Unwanted friction  is the friend of missed shifts and ghost neutrals between gears.

Less drag when the clutch lever is pulled in  (now all you have to worry about is  clutch plate drag)
Long Boy Extended Fuel Mixture Screw kit

Long Boy Extended Fuel Screw kit
pn: CRZ-SCR-3518k2
 with 2 new screws, springs, washers and o-rings

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"Long Boy"
 Finger and screwdriver adjustable extended Fuel Screws

Frustrated with trying to find an "almost 90 degree"  screwdriver to fine adjust your fuel screw for best idle and cruise?
Use Factory Pro's new "finger adjustable" fuel screw to adjust fuel screw for best throttle response. Traveling to high altitude? It's easy to lean out the lowend temporarily.

Make your life easier.

Remove old short stock fuel screw, old o-ring, old washer and old spring. The o-ring might be stuck in the carb, so take a light and make sure it's really out  (or you can't find it after you took out the screw)
Use a small bent wire to pull it out if it doesn't drop out. Keep the old parts for "spares".

Each Screw assembly kit comes with:

2 long Boy Extended Fuel Screws
2 new springs
2 new washers
2 new o-rings

                Awesome part! Seems like the only ones who make them!   bummedwi


Carb Recalibration / rejetting kits
When you desire to use the stock airbox with stock or K&N air filter.

EX250e 86-87    $89.95

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 "With the airbox kit"

Standard drop-in kit, using the stock airbox and stock, K&N or UNI stock replacement air filter.  The kit has enough jets to use with an aftermarket "street" or "race" exhaust - and also, the stock exhaust.

No slide drilling like the dj kit, is required.

inc: a selection of main jets, Celmat30 needles, clips, shims, float bowl allen screws, etc.


When you desire to use
individual air filters
and remove the airbox.

This kit Does NOT include air filters


 EX250e  86-87   C30 kit  K14

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Use the Config 30 kit for when you desire to remove the stock airbox and use individual filters.

It's not much more power, but it sure looks neater!

The kit has enough jets to use with an aftermarket "street" or "race" exhaust - and also, the stock exhaust.


When you desire to use
individual air filters
and remove the airbox.

 $159.95 WITH  air filter
 EX250 86-87  C30 kit

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Use the Config 30 kit for when you desire to remove the stock airbox and use individual filters.

The kit has enough jets to use with an aftermarket "street" or "race" exhaust - and also, the stock exhaust.

This kit includes:
Factory Pro Carb Kit
2 special BMC air filters

TL-float height gauge
$59.95 USD

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he easiest way to set float height - important when tuning for max mileage and low rpm tuning precision.

click here for "how to"


Ignition Advance Kits / rotor

RTR-KAW-5-05     $89.95

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Hi Marc,

today my Kawa-Center installed the ignition advancer kit.

This is amazing, unbelievable how my engine runs now. I'm very happy
that I'd buy the kit, it's a big advantage.

Great work from you.

Have a nice day and best regards,


Adds more lowend and midrange -

Ignition Advance Kit - NOT designed (but usable) for 250!

But look at Roland's feedback to the left.

The ex250 uses a large, 3 bolt flywheel puller that only a dealer would have.
The woodruff key from the RTR-KAW-5-05 is exactly the right key for the 250.....

If you buy the RTR-KAW-5-05 kit, you can use the supplied woodruff key and the installation instructions for the ex500...... and you'll have a nice ex500 flywheel puller tool, too!
NO! You can't buy the key without the puller, I know you can't use the puller - but - as I said, I don't make a 250 kit......


creighton smith wrote:

I really enjoyed swapping flying tales last week but what I really enjoyed was taking my bike for a ride on Saturday after installing your jet kit.
I started off with some trepidation since the 250 Ninja board is chock full of horrifying stories of repeated rejettings, needle raisings and lowerings and all manner of, after all that, very partial successes.  None of these concerns Factory Pro kits, however, and for good reason as I discovered.
I installed everything per the instructions:  3rd groove, install jets, 2 turns out (went out another half turn), and the bike ran well from the get-go.  I now have a midrange, thank you, and find myself cruising around at 7k (even as low as 4-5k if I'm trying to be really quiet) which is something the stock setup would not allow-at any rate it would not pull smoothly below 8k previously.  Full power is as good or better (My ass dyno is out of calibration, due to a boating accident I missed last year completely.)
I am delighted.  My brother in law is also convinced and may have ordered a kit already.  I'll post a recommendation on the Ninja site, but they're such bucks-down squids they'd rather waste the whole riding season than spend the bucks and the hour to get a fine running bike.
Thanks again.
Creighton Smith 




Absolutely NO carb parts sold in California.

New and improved Suzuki Teka SFI  2

with new TPS display and "MMT" Memory Module Tuner

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

parts information

EC997 dynamometer information

Product Support /Tech SECTION
click here


Mailing / Shipping address:

Factory Pro
101c Roblar Drive
Novato, CA

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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EFI and Carb Tuning - Most all FI and carb tuning

by Wheelsmith Racing

Flight Training - train with AMA race winner Todd Harrington.

The Harringtons own American Flyers, one of the most established flight training facilities in the USA.

 8 locations

The Rich Oliver Mystery School will help you discover your hidden inner strength. 
It will challenge you. It will teach you a new way of thinking, and a new way of riding. You can take your riding to an exciting new level!  

We use a variety of proven drills and training techniques. 
Practicing these techniques with our Yamaha dirt track trainers will enhance your abilities both on the track or the street.  

It doesn't matter what you ride or race, the Rich Oliver Mystery School improves everyone's skill level and mindset!

WW2 vintage flying Special

Book a sightseeing flight over the Wine Country or a Kamikaze aerobatic flight or a biplane flight over famous Sonoma Raceway, the Golden Gate Bridge and the San Francisco Bay for one or two during the spring and get a free souvenir t shirt!
(NEW!  Ask about the P-40 flights!)

707 938 2444

Just tell them that you saw this on the Factory Pro website!
Northern California's most unforgettable flying experience.  No experience required.  Open weekends!

The extension of the laboratory for engines of the Swiss Federal Institute of Technology was completed in about 1935. Its architect was Rudolf Otto Salvisberg (1882-1940). He had a successful career in Berlin but returned to Switzerland after the advent of the Nazis. His architectural style was somewhat similar to that of Erich Mendelsohn. The staircase of the laboratory is in normal use but well preserved.
Edited to the tunes of Chemical Residue by Herbie Hancock.