Harley Davidson Sportster
883 and 1200, all years
True Rear Wheel HP tm

Finger and screwdriver adjustable fuel mixture screw kit

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

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

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".

Screw assembly kit comes with:
 new extended screws
 new springs
 new washers
 new o-rings


1. Choose your shipping method


Factory "Pro Thunder" Carb Recal Kit

Easy to install and tune - NO slide drilling!

Factory Pro's Carb Recalibration kit will add more low-end / midrange, if the proper main jet is selected, more top-end power.

This is one of the HD kits that we made our reputation on - It was used in some of the fastest of the legendary AMA Pro Thunder bikes in the US, including Bartel's HD, Aaron Yates' and David Estok's bikes.
It was the jet kit of choice, being the easiest to tune (and therefore the best performing).

Excellent street manners and specifically designed to improve fuel atomization without resorting to any flim flam -
That equals better idling, better throttle response and better mileage. It's amazing that the very same needle that usually worked best on the track was the very same needle that we sell in this kit!

Some of the aftermarket jet kits actually decrease fuel atomization and that hurts power and mileage.

This kit is nothing like a "Thunderslide" dynojet kit - If you have one of those, getting a new stock slide and slide spring and installing the Factory Pro kit will bring back that smoothness, refinement and lowend power back into your $20,000 machine -

This kit includes Factory Pro "Ti" needle, 2 pilot jets and a large selection of main jets to cover both models.

Used By
Golden Gate Cycles, Corte Madera, CA
Flying Eagle Cycles, Campbellsport, WI, (920) 533-5595, Randy Erdmann


CV Carb Tuning for Keihin carbureted HD

All kit R&D was done on Factory Pro's EC997 Dyne System
F-USA True HP Standard.

Tuning Tech Notes:

K&N air filter:
Does not work well with stock exhaust and stock engine on most carbureted Sportys.
The larger main jet required by the K&N richens the lowend too much (full throttle / 1500 and 2000 rpm) hurting lowend power.
The only way to make an all stock Sporty run perfectly at low rpm with a K&N stock replacement filter is to leave the main jet too small.
If you just put in a K&N in a stock bike, you'll get pops under light acceleration.
If you have an ALL STOCK 883 (including exhaust), I'd run the stock air filter.

TL-float height gauge



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...
restart at HOME page


This Tuning Site has been visited by
www.digits.net - the oldest counting service on the web





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.