Harley-Davidson’s Sportster platform has long been a popular starting point for customizers, though 2004 was very significant as it was the first year that HD rubber-mounted the engine for a dramatic increase in comfort. As Ultimate Motorcycling put it: “The Sportster retains a kind of mystique it has carried since the first one hit the highway back in 1957. Maybe it’s the wasp-like profile the longitudinally-mounted V-twin enables when paired with the tapered, smallish tank. It is narrow, and despite the ham-can air cleaner cover that came into use in 1959 that juts out from the right side of the engine, it has a lithe, athletic look and feel.”
The builder/seller of this bike says that he specifically utilized a 2004 Sportster as “I wanted a rubber mounted engine, Buell heads, and carburetion. I spent many years as a superbike tuner, with three championships to show for it, I also built a land speed racer and hold a world record. As a rider/driver/pilot I have 54 racing seasons behind me. I built this bike for the fun of it, and show it on occasion at car shows.”
The seller (David Malmberg) has a prolific history in motorcycling – we asked him for a bio so bidders will know a bit more about the person who built the bike:
“After my own long motorcycle racing career, I started tuning for other riders. I built and tuned a GPZ750 for Chris Mencher in ’84 and won the AFM F1 class championship, then inked a deal with Bob Reinen for the next season. I built and tuned a GPZ 750 for Bob, and we won the AFM superbike championship that year. In between working with Chris and Bob I was a guest of Mr. Yoshio Kawasaki at Kawasaki Heavy Industries in Nishi Akashi, Japan. During that visit I was given cylinder heads of the not-yet-released four valve engine which gave me a head start on the next season (with Bob).
The following year I built and tuned a superbike for Dennis Fryer using a CB750 twin cam. He also won his championship. Then I put Donny Greene on the bike for one day and he finished fourth in a Formula USA event. A great ride on a modified street bike against 500 GP bikes. I also helped a few other riders at times including Dave Emde, Chris Steward, Earl Rollof, and others.
After that I switched to racing cars, racing a 944 turbo in Porsche Club events and served for several years as the chief driving instructor.
More recently, my partner and I (Marc Rittner) built a supercharged/nitrous Aprilia RSV land speed bike, which we tuned on the third member of the team (Micah Shoemaker of AF1 Racing)’s Factory Pro eddy current dyno. The bike ran in “unlimited twins” class. It was a fun adventure, all three of us rode it. With me riding we set a speed record at the Texas Mile that still stands, the only twin cylinder bike worldwide in the 200mph club on standing start miles.
Along the way I was a Development Engineer at Scripps Institution of Oceanography for 35 years (my real job) and still own an engineering company (Malmberg Design).”
This example is VIN: 1HD1CLP384K422359. The seller acquired this bike 14 years ago from a private party.
There is no odometer, true mileage is unknown. The seller acquired the donor bike with roughly 15,000 miles on it and has added approximately 300 during his ownership.
“My experienced racing friends that have ridden this bike note that it is so well sorted that it feels like a factory built bike, not quirky and rough edged enough to be a custom.”
Maintenance:
In preparation for the listing, the seller had us perform a safety inspection, clean/lube the air filter, flush the hydraulic fluids, and flush the fuel tank. Our service department notes the following on their condition report:
Gas Tank Internal Condition: Ok
Engine Oil Level: Ok
Engine Oil Quality: Ok (Age Unknown)
2T Oil Level: N/A
Coolant Level: N/A
Coolant Quality: N/A
Front Hydraulic Fluid Level: Ok
Front Hydraulic Fluid Quality: New (<1.5% of moisture contamination)
Rear Hydraulic Fluid Level: Ok
Rear Hydraulic Fluid Quality: New (<1.5% of moisture contamination)
Clutch Hydraulic Fluid Level: N/A
Clutch Hydraulic Fluid Quality: N/A
Final Drive Condition: Ok
Headlight High Beam: Ok
Headlight Low Beam: Ok
Passing Light: Ok
Parking Light: Ok
Turn Signals: Ok
Tail Light: Ok
Brake Light (Front Switch): Ok
Brake Light (Rear Switch): Ok
Plate Light: Ok
Horn: Ok
Kill Switch: Ok
Brake Pad % Remaining Front: 90%
Brake Pad % Remaining Rear: 90%
Forks: Ok
Shock/s: Ok
Tire Date Code Front: 15/17
Tire Date Code Rear: 15/17
Tire % Remaining Front: 90%
Tire % Remaining Rear: 90%
Tire Press. Front: 29 PSI
Tire Press. Rear: 28 PSI
Battery Standing Voltage: 12.8V
Charging Voltage @ 4k RPM: 14.2V
Running Condition: Runs Well on Bench, Runs Well on Test Ride
Test Ride Completed: Yes
Test Ride Distance: 4 Miles
Notes:
-True mileage unknown due to lack of speedometer/odometer, only gauge present is tachometer
Customer Notes:
-Battery tender lead present on right hand side of bike towards the rear
-Bike utilizes OEM Harley-Davidson wiring harness and should be on a tender if it will sit longer than 48 hours
-Carburetor bowl should be drained when not in use due to ethanol concentration with local gas regulation
-Bike is cold blooded and should be fully warmed up prior to riding
-Aluminum fuel tank
-Brakes are soft as they are specified for dirt track usage
-Front brakes need to break-in/warm up to coat the rotors and have a solid bite. They are sport bike quality when ridden to clean off the rotors.
-Carbs are 48mm Keihin flat slide carb
-89 HP when dyno’d
Modifications:
Per the seller:
– Engine
Andrews N4 cams, 48mm Keihin flatslide carb, Dyna programmable ignition, Bubs pipes. High flow air cleaner. And a bunch of other fiddling with manifold matching and so on. Jetting and ignition advance curve development done on a dyno. At the time the peak hp was a surprising 89 hp. A stock crankshaft means the redline is 6,000 rpm.
– Wheels
Hubs custom made for this bike, front XS650 pattern, rear early Harley pattern (dirt track correct). Hubs machined by Henny Ray Abrahms (A+A Racing), out of 7075 billet, mirror polished and black anodized. Rims custom made by Sun Rims, clear anodizing stripped off and re anodized in black. Buchanan’s stainless steel spokes. Final drive converted to chain.
– Brakes
Front rotor carriers custom made by A+A racing, rotors cut from blanchard ground mechanite iron, gold zinc plated. Calipers are 4 piston Brembo.
Rear brake features full floating rotor, and full floating caliper (dirt track correct), caliper is a 1″ Brembo copy of the traditional Grimeca caliper no longer produced.
– Suspension
Front end features fully adjustable Showa big piston fork, triple clamps, and calipers as used in the European XRX road racing series (they were interesting to get hold of). Rear suspension uses Works Performance shocks that were custom made for this bike. Suspension is plush and well sorted.
– Bodywork
Tank is hand formed aluminum, tail section is fiberglass, Saddleman seat. Seat and tail section, along with footpeg assemblies sourced from Steve Storz.
Paint in traditional Harley dirt track team colors by famous hot rod painter Kevin Norton. ($$$)
Hidden functional turn signals.
Design, planning, engine build, tuning, assembly, along with brackets, mounts, spacers, and endless details by builder.
Inside of the tank:
It is riding on Shinko SR267 flat track tires with date codes of 1517 and 1517.
The sale includes two keys and a left hand mirror.
Cosmetic Blemishes: please see the album in the “Photos” tab for all known cosmetic blemishes. Here is a selection:
Currently located in Panorama City, California, (please make an appointment for an inspection) this Harley-Davidson is offered on a clean California title with registration current through June 2026.
Have any Sportster stories or questions about this listing? Let us know in the “Comments” tab!
