Street Chopper Homepage

S&S G Enhancement

And the DaVinci Fire Power Carburetor
February, 2009
By Greg Friend
2003 Big Dog Mastiff Right Side Front Half View
2003 Big Dog Mastiff Right Side Engine View
The '03 Big Dog Mastiff with... 
   
  read full caption
2003 Big Dog Mastiff Right Side Engine View
The '03 Big Dog Mastiff with a 107ci S&S and a stock G carb, the stock Mastiff put out 94.1 hp and 102.6 lb-ft of torque. With the air cleaner assembly and backing plate removed, DaVinci drained the fuel in the bowl, removed the float bowl screws, and then the bowl itself.
2003 Big Dog Mastiff Full Engine View
Next, the main discharge tube... 
   
  read full caption
2003 Big Dog Mastiff Full Engine View
Next, the main discharge tube was pulled out of the carb body assembly, so he could install the DaVinci kit.
0306Stc Davinci04 Z
Here is the entire DaVinci... 
   
  read full caption
0306Stc Davinci04 Z
Here is the entire DaVinci kit: a special booster anchor socket wrench, Loctite, annular discharge booster, booster anchor, discharge tube, and main jet.
2003 Big Dog Mastiff Engine View
To install the kit, we simply... 
   
  read full caption
2003 Big Dog Mastiff Engine View
To install the kit, we simply placed the booster anchor into the supplied socket wrench with a little Loctite on the threads and placed the booster inside the venturi of the carb. Then, we put the anchor and socket into the main discharge tube hole and tightened it down snugly. We then, screwed the new discharge tube into the main discharge tube hole along with the included jet, just as we would with a normal S&S G carb.
2003 Big Dog Mastiff Engine View
Don't forget to put on the... 
   
  read full caption
2003 Big Dog Mastiff Engine View
Don't forget to put on the float bowl gasket, then screw the float bowl back into place.
2003 Big Dog Mastiff Right Side Engine View
7Using a hex key, DaVinci... 
   
  read full caption
2003 Big Dog Mastiff Right Side Engine View
7Using a hex key, DaVinci bolted the backing plate into the head and put the air cleaner and cover back on in preparation for our second dyno run. All DaVinci did was bolt on the DaVinci kit and the bike produced 99.6 hp and 107.8 lb-ft of torque -- a 5.5hp and 5.2lb-ft of torque gain in 15 minutes!
2003 Big Dog Mastiff Carburetor View
The DaVinci Fire Power Carburetor... 
   
  read full caption
2003 Big Dog Mastiff Carburetor View
The DaVinci Fire Power Carburetor is a true performance upgrade from the original S&S G. You can see some of the differences between the S&S ...
2003 Big Dog Mastiff Carburetor View
.... and the DaVinci Fire... 
   
  read full caption
2003 Big Dog Mastiff Carburetor View
.... and the DaVinci Fire Power. Tthe Fire Power carb comes chrome-plated, the annular power booster is factory installed, it has a replaceable high-speed air-bleed to allow tuners to customize their fuel curve, extended hexagon bowl bolt screws to improve access and reduce time when removing the bowl while it is still on the bike, an extended idle screw knob that allows adjustments to be made by hand, and the main fuel jet can be changed using a standard jet tool without removing the bowl.
0306Stc Davinci09 Z
The inner diameter of the... 
   
  read full caption
0306Stc Davinci09 Z
The inner diameter of the venturi on the Fire Power carb has been precision machined and bored from the original 44mm to 48mm, then hand blended to final size, shape, and finish.
0306Stc Davinci10 Z
To further increase airflow,... 
   
  read full caption
0306Stc Davinci10 Z
To further increase airflow, the butterfly shaft is milled from 0.280 inches to 0.170 inches. This increases the air flow to 385 cfm -- a 36cfm increase or about a 10-percent total gain over the stock S&S G.
2003 Big Dog Mastiff Side Engine View
Installation of the Fire Power... 
   
  read full caption
2003 Big Dog Mastiff Side Engine View
Installation of the Fire Power carb is just as easy as installing a stock S&S G. We detached the fuel line, unbolted the carb from the manifold from the primary side of the bike, and removed the throttle cable ferrules from the throttle spool.
2003 Big Dog Mastiff Engine And Carburetor View
We grabbed the new Fire Power... 
   
  read full caption
2003 Big Dog Mastiff Engine And Carburetor View
We grabbed the new Fire Power carb and inserted the ferrules into the Fire Power throttle spool. Then, we put the phenolic spacer back between the carb and manifold, and bolted the carb to the manifold.
2003 Big Dog Mastiff Full Engine View
Then, we hooked the fuel line... 
   
  read full caption
2003 Big Dog Mastiff Full Engine View
Then, we hooked the fuel line back onto the fuel inlet on the bottom of the bowl and tightened the worm screw on the hose clamp. The backing plate went on next, followed by the air cleaner and the cover.
2003 Big Dog Mastiff Right Side Driver View
Nigel Patrick of Patrick Racing... 
   
  read full caption
2003 Big Dog Mastiff Right Side Driver View
Nigel Patrick of Patrick Racing performed his final run of the day with the Fire Power carb installed. The bike still looks stock, but the numbers don't lie.
0306Stc Davinci15 Z
Our final numbers of the... 
   
  read full caption
0306Stc Davinci15 Z
Our final numbers of the morning were 106 hp and 107.1 lb-ft of torque -- the Fire Power carb produced 6.4 more hp than the DaVinci Kit and a total of 11.9 hp and 4.5 lb-ft of torque more than the stock S&S G!

Toyota Tundra Research
Toyota Tundra Get all the information you need on the new Toyota Tundra. The Tundra comes with a V8 standard engine and goes for a suggested retail price of $28,405.00. It also has drivers side crash test ratings of 4 stars and passengers side crash test ratings of 4 stars. You also might want to research the Dodge Durango and the GMC Sierra.

Related Articles

 
2005 Evel Knievel G-Bob - G-Spot Customs
There are so many custom builders in the motorcycle industry that it can be hard to stand out. Geoff Giles, fabricator, racer, head janitor, and owner of G-Spot Customs in Denver has brought a new... more
 
G&J Aircraft's Dimple Die Set: Street Chopper's Toolbox
In this edition of Street Chopper Toolbox, we show you how to install a part on a Rigid that you've probably seen on World War II-era aircraft.... more
 
Kit Bike 123's - Tech
Building A BBC Merc Springer... more
 
2001 Harley Davidson - The '60s Again
The '60s Again. Only Better.... more
 
1998 Buell S1W - Two In The Pinks
Felony Flyers' Racing Rigid... more
 
Street Chopper's '80s Issue - Back In The Day...
Ahh the '80s. For most of us, there's plenty of Polaroids and VHS (or Beta) videos from that decade that inspire nostalgia laced with a little good-natured humiliation. Flipping through the pages... more
 
'04 Rebel Yell Inc.'s Custom Chopper - Sick 4 Life
In as much as we love production customs, the term is a bit of an oxymoron in that while the bikes are breeds apart from stock Harleys, they're still production models. That said, we rarely see... more
 
2007 Count's Kustoms NUB Chopper - T*E*S*T*E*D
Street Chopper Magazine tests the 2007 Count's Kustoms NUB chopper -- a bike that starts at $19,999.... more