2012 Harley-Davidson FLSTF Fat Boy Specifications

Name: 2012 Harley-Davidson FLSTF Fat Boy
Brand: Harley-Davidson

Custom / cruiser • Specs last verified 13 July 2026

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2012 Harley-Davidson FLSTF Fat Boy Overview

For 2012, Harley-Davidson offers the FLSTF Fat Boy as a custom / cruiser motorcycle with 1690 cc on tap. The 2012 Harley-Davidson FLSTF Fat Boy is built around a Four stroke, V-Twin, Twin Cam 103B Pushrod-operated, overhead valves with hydraulic, self-adjusting lifters, two valves per cylinder, with Integrated Oil-Cooler engine, a compression ratio of 9.6:1. Out on the road, the FLSTF Fat Boy delivers 134 Nm @ 3500 rpm of torque. In everyday use, the 2012 FLSTF Fat Boy tips the scales at 329 kg, carries a 18.9-litre fuel tank, offers a seat height of Laden 635 mm and spans a 1635 mm wheelbase. That's roughly 28.4 kg heavier than the average custom / cruiser motorcycle in our database. Every technical detail, from suspension travel to tyre sizes, is covered in the full 2012 Harley-Davidson FLSTF Fat Boy spec sheet below.

2012 FLSTF Fat Boy - Pros & Cons

Strengths

Fuel injection: No choke, no jetting, no altitude compensation to think about - fuel injection just works across a wider range of conditions than carburetion.
Accessible seat height: At just Laden 635 mm, flat-footing at a stop is easy for most riders - a genuine confidence builder for less experienced owners.
Large fuel range: With a 18.9-litre tank, this isn't a bike you'll be stopping for fuel every hour - a real asset on longer trips.
Low-maintenance final drive: Belt final drive is about as close to maintenance-free as motorcycle drivetrains get.

Considerations

Age-related wear: No particular mechanical concern flags for the FLSTF Fat Boy - condition on any used example comes down to how well it's been looked after.

Wear Points & Servicing Notes

Heat management in traffic

Air cooling on the FLSTF Fat Boy keeps the mechanical layout simple, but heat management in slow traffic needs more attention than on a liquid-cooled bike - plan routes and gear accordingly in warmer conditions.

Fuelling & injector care

Fuelling on the FLSTF Fat Boy comes from Electronic Sequential Port Fuel Injection (ESPFI). Cold starts and throttle response stay consistent across altitude and temperature, the main practical edge over a carbureted equivalent.

Brake disc and pad wear

Single 292 mm disc, 4 piston caliper up front provides the primary stopping power; inspect disc thickness and pad wear at each tyre change to catch scoring before it becomes a rotor replacement.

Suspension condition on used examples

Suspension duties are handled by 41.3 mm telescopic, chrome dust covers up front and Hidden, horizontal-mounted, coil-over shock at the rear. Weeping fork seals aren't a dealbreaker on a used bike, but they're a fair basis for negotiating price.

Final drive maintenance

Belt final drive keeps day-to-day maintenance minimal on the FLSTF Fat Boy - just periodic tension and wear checks rather than the regular cleaning a chain demands.

Frame & chassis check

The Mild steel, tubular frame; rectangular section backbone; stamped, cast and forged junctions, forged fender supports; MIG welded chassis holds up well with normal use; on a used bike it's still worth checking the head-stock and swingarm pivot area for impact damage or corrosion.

Handling the weight at a standstill

The FLSTF Fat Boy's 329 kg kerb weight is worth factoring into how you handle it at a standstill - parking-lot manoeuvres need a bit more deliberate technique than on a lighter machine.

FLSTF Fat Boy - Buying & Maintenance Guide

What to check before buying

A pre-purchase check on the 2012 Harley-Davidson FLSTF Fat Boy should cover the same ground every time: service history, chain and sprocket condition, and any oil seepage around the casings. Start it from cold if you can - a well-kept FLSTF Fat Boy settles to a smooth idle within seconds.

Oil and filter changes

Oil changes are the cheapest insurance you can buy for a FLSTF Fat Boy's engine - keep to the manufacturer's interval rather than stretching it. Use the viscosity grade the manual specifies, not whatever's on sale.

Fuel system care

Injector systems like the FLSTF Fat Boy's hold up well with basic care - decent fuel, an occasional cleaner additive, and draining old fuel before any layup longer than three months.

2012 Harley-Davidson FLSTF Fat Boy - Frequently Asked Questions

What engine does the 2012 Harley-Davidson FLSTF Fat Boy have?

The 2012 Harley-Davidson FLSTF Fat Boy uses a Four stroke, V-Twin, Twin Cam 103B Pushrod-operated, overhead valves with hydraulic, self-adjusting lifters, two valves per cylinder, with Integrated Oil-Cooler engine with 1690 cc of displacement. It is air cooled.

How much does the 2012 Harley-Davidson FLSTF Fat Boy weigh?

The 2012 Harley-Davidson FLSTF Fat Boy weighs 329 kg. This is the manufacturer's wet figure.

How much power does the 2012 Harley-Davidson FLSTF Fat Boy make?

The 2012 Harley-Davidson FLSTF Fat Boy produces 134 Nm @ 3500 rpm of torque.

What is the fuel tank capacity of the 2012 Harley-Davidson FLSTF Fat Boy?

The 2012 Harley-Davidson FLSTF Fat Boy has a 18.9-litre fuel tank. At around 5-6 litres per 100 km, that is roughly 315-377 km between stops.

Is the 2012 Harley-Davidson FLSTF Fat Boy suitable for shorter riders?

The 2012 Harley-Davidson FLSTF Fat Boy has a seat height of Laden 635 mm. This is a comfortable, accessible height for most riders.

What brakes does the 2012 Harley-Davidson FLSTF Fat Boy have?

The 2012 Harley-Davidson FLSTF Fat Boy uses Single 292 mm disc, 4 piston caliper at the front and Single 292 mm disc, 2 piston caliper at the rear.

What tyre sizes does the 2012 Harley-Davidson FLSTF Fat Boy use?

The 2012 Harley-Davidson FLSTF Fat Boy runs 140/75R17 67V front and 200/55R17 78V rear tyres. A good selection of sport, touring and all-weather rubber is available in these sizes.

What gearbox does the 2012 Harley-Davidson FLSTF Fat Boy have?

The 2012 Harley-Davidson FLSTF Fat Boy is fitted with a 6 Speed transmission.

Harley-Davidson FLSTF Fat Boy Spec Evolution

The Harley-Davidson FLSTF Fat Boy was produced across 8 model years (1995-2012). The table below highlights the key specifications that changed across the production run - useful whether you are comparing years or tracking down a specific variant.

Specification	1995	1998	2007	2008	2009	2010	2011	2012
Wet Weight	320 kg / 706 lbs	320 kg / 706 lbs	329.0 kg / 725 lbs	329.0 kg / 725 lbs	329.0 kg / 725 lbs	329.0 kg / 725 lbs	329.0 kg / 725 lbs	329 kg / 725 lbs
Engine Detail	Four stroke, 45° V-Twin, OHV, 2 valves per cylinder.	Four stroke, 45° V-Twin, OHV, 2 valves per cylinder.	Four stroke, Twin Cam 96BTM Valves Pushrod-operated, overhead valves with hydraulic, self-adjusting lifters; two valves per cylinder	Four stroke, Twin Cam 96BTM Valves Pushrod-operated, overhead valves with hydraulic, self-adjusting lifters; two valves per cylinder	Four stroke, Twin Cam 96BTM Valves Pushrod-operated, overhead valves with hydraulic, self-adjusting lifters; two valves per cylinder	Four stroke, Twin Cam 96BTM Valves Pushrod-operated, overhead valves with hydraulic, self-adjusting lifters; two valves per cylinder	Four stroke, Twin Cam 96BTM Valves Pushrod-operated, overhead valves with hydraulic, self-adjusting lifters; two valves per cylinder	Four stroke, V-Twin, Twin Cam 103B Pushrod-operated, overhead valves with hydraulic, self-adjusting lifters, two valves per cylinder, with Integrated Oil-Cooler
Seat Height	-	-	Laden 635 mm / 25.0 in Unladen 690 mm / 27.1 in	Laden 635 mm / 25.0 in Unladen 690 mm / 27.1 in	Laden 635 mm / 25.0 in Unladen 690 mm / 27.1 in	Laden 635 mm / 25.0 in Unladen 690 mm / 27.1 in	Laden 635 mm / 25.0 in Unladen 690 mm / 27.1 in	Laden 635 mm / 25.0 in Unladen 690 mm / 27.1 in
Fuel Capacity	19 Litres / 5.0 US gal	19 Litres / 5.0 US gal	18.9 Litres / 5.0 gal	18.9 Litres / 5.0 gal	18.9 Litres / 5.0 gal	18.9 Litres / 5.0 gal	18.9 Litres / 5.0 gal	18.9 Litres / 5.0 US gal
Displacement	1337 cc / 81.5 cu-in	1337 cc / 81.5 cu-in	1584 cc / 96 cu-in	1584 cc / 96 cu-in	1584 cc / 96 cu-in	1584 cc / 96 cu-in	1584 cc / 96 cu-in	1690 cc / 103.1 cub in.
Wheelbase	-	-	1715 mm / 67.5 in	1715 mm / 67.5 in	1715 mm / 67.5 in	1715 mm / 67.5 in	1715 mm / 67.5 in	1635 mm / 64.2 in
Brakes - Front	Single 292mm disc 4 piston caliper	Single 292mm disc 4 piston caliper	Single 292mm disc 4 piston caliper	Single 292mm disc 4 piston caliper	Single 292mm disc 4 piston caliper	Single 292mm disc 4 piston caliper	Single 292mm disc 4 piston caliper	Single 292 mm disc, 4 piston caliper
Brakes - Rear	Single 292mm disc 4 piston caliper	Single 292mm disc 4 piston caliper	Single 292mm disc 4 piston caliper	Single 292mm disc 4 piston caliper	Single 292mm disc 4 piston caliper	Single 292mm disc 4 piston caliper	Single 292mm disc 4 piston caliper	Single 292 mm disc, 2 piston caliper

Key Specifications

Engine

Four stroke, V-Twin, Twin Cam 103B Pushrod-operated, overhead valves with hydraulic, self-adjusting lifters, two valves per cylinder, with Integrated Oil-Cooler

Power

Not published by manufacturer

Torque

134 Nm / 13.7 kgf-m / 98.8 ft. lbs @ 3500 rpm

Top Speed

Not published by manufacturer

Weight

329 kg / 725 lbs

Fuel Capacity

18.9 Litres / 5.0 US gal

Full 2012 Harley-Davidson FLSTF Fat Boy Specifications

Year 2012

Make Model Harley Davidson FLSTF Fat Boy

Seat Height Laden 635 mm / 25.0 in Unladen 690 mm / 27.1 in

Wheelbase 1635 mm / 64.2 in

Length 2396 mm / 94.3 in

Fuel Capacity 18.9 Litres / 5.0 US gal

Maximum Load / GVWR 526.0 kg / 1160 lbs

Oil Capacity 3.3 Litres

Wet Weight 329 kg / 725 lbs

Max Torque 134 Nm / 13.7 kgf-m / 98.8 ft. lbs @ 3500 rpm

Displacement 1690 cc / 103.1 cub in.

Engine Detail Four stroke, V-Twin, Twin Cam 103B Pushrod-operated, overhead valves with hydraulic, self-adjusting lifters, two valves per cylinder, with Integrated Oil-Cooler

Bore x Stroke 98.4 x 111.1 mm

Compression Ratio 9.6:1

Cooling System Air cooled

Exhaust Chrome, over/under shotgun exhaust with dual mufflers

Fuel Induction Electronic Sequential Port Fuel Injection (ESPFI)

Ignition Single-fire, non-wasted, map-controlled spark ignition

Starter Electric

Final Drive Belt

Gear Ratios 1st 9.311 / 2nd 6.454 / 3rd 4.793 / 4th 3.882 / 5th 3.307 / 6th 2.79

Transmission / Drive 6 Speed

Frame Type Mild steel, tubular frame; rectangular section backbone; stamped, cast and forged junctions, forged fender supports; MIG welded

Suspension - Front 41.3 mm telescopic, chrome dust covers

Suspension - Rear Hidden, horizontal-mounted, coil-over shock

Rake 31°

Trail 147 mm / 5.8 in

Brakes - Front Single 292 mm disc, 4 piston caliper

Brakes - Rear Single 292 mm disc, 2 piston caliper

Tyres - Front 140/75R17 67V

Tyres - Rear 200/55R17 78V

Wheels Optional Style Type Mirror Polished Chrome, Bullet Hole Disc Cast Aluminum (front and rear)

Wheels - Front Silver, Bullet Hole Disc Cast Aluminum

Wheels - Rear Silver, Bullet Hole Disc Cast Aluminum

Specifications are compiled from manufacturer documentation and cross-referenced technical sources, and corrected on an ongoing basis. Spot an error? Let us know.