Road Test:, ex250 test

Kawasaki EX250 f/h, GPX250r, 88-07

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 -



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

The Blue 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 and no 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)

or you could pretend it's:

$34 and Free UPS ground shipping!
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From Factory Pro - the originator of motorcycle shift kits.

Blue Shift Spring

250 guys have been asking when we would make a 250 Shift Spring.

We did.

Improve lazy shifting - virtually eliminate missed shifts - virtually eliminate false neutrals -  help prevent gearbox damage caused by missed shifts.
Not a quickshifter, this spring makes the stock shift mechanism shift quicker by 3ms to 7ms per shift.

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

The Blue spring

JUST right = MAGIC shifting.

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.

Long Boy Extended Fuel Screws

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

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

"Long Boy"
 Finger adjustable and screwdriver extended Fuel Screw assembly

Frustrated with trying to find an "almost 90 degree"  screwdriver to fine adjst 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




Carb Recalibration Kits

 When you desire to use the stock airbox with stock or K&N air filter.

pn: CRB-K13-1.0

   for 88-07     $89.95

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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: main jets, Celmat30 needles, clips, shims, float bowl allen screws, etc.

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

 for 88-07     $89.95

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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.



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

WITH special air filter/s

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
Air filter/s

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TL-float height gauge    $59.95

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The 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,


Ignition Advance Kit - not specifically for 250

We do NOT make an ignition advance kit for the ex250!

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 the same key that fits 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......
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......

To the right,
parts diagram of shift detent mechanism


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!

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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!)

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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.