85-96 K75F Features

The features of my K75 Frankenbrick and summarized in the table below followed by descriptions of them.

Brakes

• K1100 Front Brakes

• Hybrid ABS

• Vented Rear Rotor

• Braided Stainless Brake Lines

Engine/Fuel System

• Bosch Series 2 Fuel Injectors

• New Insulated Fuel Lines

• NGK Iridium Spark Plugs

• Magnecor Spark Plug Leads

• Stainless TB Hose Clamps

• New Rubber Bits

• Nicer Cover Bolts and New Grommets

Suspension/Drive Train

• 32:11 Paralever Rear End

• K1100 Transmission

• Ohlins Shock

• Newer Clutch Plate

• K1100 Front End

• Fork Protectors

• K1100LT Wheels

• Radial Tires

• New Valve Stems

• Ride-On Tire Protection System

Electrical

• 50 Amp Alternator Upgrade

• Custom Heavy Gauge Battery Cables

• Starter

• Odyssey PC680 Battery

• Aux fuse block

• Fiamm Horns

• TomTom RIDER GPS

Instruments/Controls

• REAL Cruise Control w/ OEM Switch

• "Euro" Headlight Switch

• K1100RS Handlebars

• Manic Salamander Bar Ends

• Heated Grips

• ProGrip Gel Grips

• Altitude Switch

• Repositioned Dash Pad w/ Powerlet Socket

• All LED Instrument Cluster

• Calibrated Speedometer

• 12 Hour Clock

• Choke Light

• Odometer Setting

• K1100RS Peg Plates

• K1100 Shift Lever w/ Ilium Works Extender

Lighting

• 130/90W Headlight w/ Relays

• LED Parking Light

• CATZ XLO Conspicuity Lights

• Hella HID Driving Lights

• Enhanced LED Tail Lighting

• Strobing LED Brake Light

• Rear Turn Signals Double As Brake Lights

• Kisan SignalMinder w/ LED Turn Signals

• Radiantz LED Mirror Turn Signals

• LEDified Side Reflectors
  
   

Cosmetic/Miscellaneous

Fluids/Filters

• Moly Spline Lube

• Mobil 1 Synthetic Engine Oil

• Aluminum Oil Filler Cap

• Bosch Oil Filter

• Royal Purple 75W-140 Synthetic In Transmission

• Mobil 1 75W-90 In Final Drive

• Guard Dog Moly Additive In Transmission and Final Drive

• Redline Water Wetter In Cooling System

• Honda SS-8 Fork Oil

• Napa Gold 3032 Fuel Filter

• OEM Air Filter

Seats

• Corbin Gunfighter Seat

• Corbin Canyon Dual Sport Seat

• Corbin Dual Tour

• Rick Mayer Custom Seat

Luggage/Tools

• OEM 22 Liter Top Case

• Line-X'd City Cases

• Gen 3 System Cases

• Electrified OEM Tank Bag

• Complete OEM Toolkit

• Spare Clutch & Throttle Cables

Brakes

K1100 Front Brakes

After riding the later K bikes, the stock front brakes on a K75 don't seem adequate.  This bike K1100 front brakes with a 20mm master cylinder, four piston calipers and floating rotors.  What would take a whole handful of brake on a stock K75 takes a light two fingers on this bike.

Hybrid ABS

Since the K1100 front end has a different front ABS sensor and modulator I had to do a few wiring and brake line modifications to get a K75 ABS wiring harness to work with a K1100 ABS control unit but it worked right off of the bat.

Vented Rear Rotor

The rear rotor is a vented rear ABS rotor from a 94-on K1100.

Braided Stainless Steel Brake Lines

The front brakes have new smoke-colored K1100 Galfer braided stainless steel lines. The rear brake has braided stainless lines that I pulled from a K100RS-SE that I parted.

Engine/Fuel System

Bosch Series 2 Fuel Injectors

The bike has freshly reconditioned Bosch Series 2 fuel injectors that have four holes and have a "mistier" spray pattern than the original Series 1 injectors.

Apparently this injector upgrade is popular with the Jeep crowd.  Here's a short YouTube video demonstrating the difference in the spray patterns between the Series 1 and Series 2 injectors.

New Insulated Fuel Lines

One of the issues with K75s is that the return line to the tank from fuel rail runs right behind the left side of the radiator.  This heats up the gas returning to the tank. I insulated all of the fuel lines and the fuel rail to mitigate this.

After the initial build, I later went back and replaced all of the external fuel lines with brand new FI-rated fuel lines.

NGK Iridium Spark Plugs

NGK DR7EIX Iridium spark plugs.

Magnecor Spark Plug Leads

 New Magnecor aftermarket 8mm spark plug leads.

Stainless Steal Throttle Body Hose Clamps

I'm not a fan of the one-use Oetiker style hose clamps used on K bikes so instead I used some narrow stainless steel worm drive hose clamps.

Fuel Injector Cover

In order to hide the fuel injectors and throttle bodies for a cleaner look, I fashioned this cover plate out of 1/8" aluminum and had it powder coated.  I later needed to remove it when I installed the K1100RS fairing.

New Rubber Bits

I replaced all of the rubber parts of the fuel system with new parts including the crank case breather hose as pictured above.

Nicer Cover Bolts and New Grommets

The original engine cover bolts were looking a bit old so I sorted through my stash to find some better ones, cleaned those up and installed them with new grommets from BMW.

Suspension/Drive Train

32:11 Paralever Rear End

The bike started out with 32:10 K75 monolever rear end setup but I ride this bike pretty hard and I found the "jacking effect" annoying so I converted the rear end to a 32:11 paralever rear end.

K1100 Transmission

In order to support mounting of the front of the lower strut for the paralever setup I installed a K1100 transmission with 24k.  The only difference in gearing between the K75 transmission and this is that fifth gear is slightly "taller" on the K1100 transmission - 1.67 vs. the 1.61 K75 fifth gear.

Before installing the paralever rear end I took it for a freeway ride to see how much the difference in gearing would impact RPMs. With the K75 transmission and 32:10 final drive the bike ran at 57/58 MPH (calibrated speedometer) at 5,000 RPM in fifth gear. After the conversion it ran at about 4,425 RPM for the same speed.  This lines up pretty well with my calculation that it should be around 4,400.  This also reduces the torque by about 11% or so but I just ride the bike harder to make up for that and use third gear for passing.

Ohlins Shock

Fortunately I had an extra K1100 Ohlins shock lying around when I did the final drive conversion.

Newer Clutch Plate

While I had the clutch out to install a new clutch nut O-ring as preventative maintenance, I cleaned up all of the clutch parts and the inside of the bellhousing. I installed a clutch plate that measures 5.25mm. Factory specs are 4.5-5.55mm so this one’s got a lot of life left in it.

K1100 Front End

Wanting K1100 front brakes and due to the differences in the wheel, rotors, calipers and fork diameter, I came to the conclusion that the easiest way to do this was to install a complete front end which includes:

K1100LT Wheels

I used K1100 front (2.5x18) and rear (3x17) 3-spoke wheels. I considered using the wider K1100RS wheels but figured the K1100LT wheels would be lighter, have less rotational inertia and therefore spin up easier, not to mention easier turn-in.

Radial Tires

Another advantage of using the K1100LT wheels was that it allows me to run stock sized radials.  I'm running a Bridgestone BT023 on the front and an Avon Azaro 46 on the rear.  The bike handles much better on radial tires than it did on bias ply tires.

Valve Stems

I'd planned on installing metal valves stems when I had the tires mounted but didn't have any at my finger tips so I replaced the old BMW rubber valve stems with brand new ones.  At my next tire change I'll be installing metal ones.

Ride-On Tire Protection System

I use this in my other bikes as well.  It automatically dynamically balances the tires as they age and also provides sealant protection for punctures up to 1/4".

Electrical

50 Amp Alternator Upgrade

The stock 32 amp 450W alternator that came on K75s up to 1993 was more than adequate for running the bike and had about 100-125 "spare" watts but once you start adding additional lighting, heated grips and gear, etcetera you quickly burn those up.  This bike has the later 50 amp 700W alternator so that I can run a high watt headlight bulb along with a pair of 70x70W aux lights..

Custom Heavy Gauge Battery Cables

I made my own custom heavy gauge cables for the battery ground cable and the cable from the 50 amp alternator to the battery.

Starter

This was the nicest starter I had lying around. 60K from a 96 K1100RS.

Odyssey PC680 Battery

These are great sealed no maintenance batteries.  In my experience they are very dependable and last a long time.  It's also a "half-sized" battery which cuts down on weight some.

Auxiliary Fuse Block

I'm not a fan of using in-line fuses when adding electrical components to a vehicle so I installed this four circuit fuse block next to the factory fuse block.  Then I made some laminated labels for both fuse blocks and installed them with 3M double-sided automotive tape.

Fiamm Horns

With the exception of the K75RT, K75s came from the factory with a single disc horn that is barely audible and sounds like a scooter.  I installed a pair of Fiamm 135 dB horns that were used in the LT/RS/RT models and also BMW cars of the era.

TomTom Rider GPS

TomTom Rider GPS mounted/powered on the left handlebar.  It's not the best GPS but it works and, with some aftermarket software that I have running on it, it doubles as a large digital speedometer while recording GPX tracks of everywhere that I ride.

Instruments/Controls

Real Cruise Control w/ A BMW OEM Switch

Audiovox CCS-100 vacuum cruise control.  I use the up/down windscreen switch of a K1100LT left combination switch to control it.

On a K75, the wiring harness connector for the headlight, turn signal and horn is different from a K1100's so I cut the wires off and grafted on a K75 connector so it would work with a K75 main wiring harness. Then I use the three wires of the other connector to operate the cruise control.

"Euro" Headlight Switch

From the factory, US model K bikes came with an "always-on" headlight and no headlight switch while bikes for other countries had what's commonly referred to as a Euro switch.

K1100RS Handlebars

When I first put the K75F together, I installed K75C handlebars for a more upright riding position.  However, once I had the radials and K1100RS fairing installed, I found that the C bars didn't allow me to lean forward enough and hindered my riding.  So I replaced them with more aggressive K1100RS handlebars.

Manic Salamander Bar Ends

Chrome Manic Salamander 18 oz bar ends.

Heated Grips

Symtec heated grips wired through a BMW OEM heated grip switch.

ProGrip Gel Grips

ProGrip 699 open-ended gel grips. These are my favorite grips for K bikes and work well with the heated grips.

Altitude Switch

US models of K75s/K100s have something usually referred to as the "altitude plug." It’s supposed to be inserted into a connector that’s cleverly hidden along the left frame rail in the fuel injection wiring harness. When operating above approximately 4,000 feet above sea level, you’re supposed to insert the “altitude” plug. It closes a circuit that tells the L-Jetronic fuel injection computer to adjust the mixture in order to compensate for the thinner air.

Instead of dismounting every time you pass through 4,000 feet, it’s much more convenient to simply wire it up to a switch. I modified a flasher switch so that the down position activates the flashers normally while the up position triggers a relay to complete the altitude circuit.

All LED Instrument Cluster

All of the backlighting and indicator bulbs in the instrument cluster have been replaced by LEDs.   Not only do they do a better job of lighting but also last "forever."

Calibrated Speedometer

From the factory, K bike speedometers usually run about 10% fast. I find this annoying so I recalibrated the speedometer to read accurately.

12 Hour Clock

Being American I'm used to a 12, not 24, hour clock. The LCD clock in the instrument cluster has been modified to be a 12 hour clock.

Choke Indicator Light

On 1990 and earlier K bikes, BMW installed a switch on the "choke" that illuminated an indicator in the instrument cluster to remind you if you'd left the choke on. In 1991, they discontinued installing the switch but left the unused wiring for it in the main wiring harness. By installing a chooke switch (with a spacer), I was able to make the choke inicator work on this bike's 1992 wiring harness.

Odometer Setting

When I installed the K1100RS fairing and radial tires on the final iteration of this bike, I reset the odometer to 750,000 miles just for kicks. However, if you added up the miles from all of the different bikes' parts that went into this bike then it's probably low. (The blue painter's tape is to remind me that the tires are new and haven't been scrubbed in yet.)

K1100RS Peg Plates

Since I like the looks of them and they have a better rear brake return spring, I installed rubber mounted K1100RS peg plates.

K1100 Shift Lever w/ Ilium Works Extender

K1100 gear shift lever with an Ilium Works shift lever extender. It had some diamond hashing on it which I suspected would cause accelerated boot wear on my left boot so I put a piece of 1” heat shrink on it.

Lighting

130/90W Xenon Headlight With Relays

I installed headlight relays and installed a 100/90W Xenon H4 bulb.

LED Parking Light

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CATZ XLO Conspicuity Lights

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HID Driving Lights

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Enhanced LED Tail Lighting

I added banks 6 LEDs to each side of the tail light lens.

Strobing LED Brake Lights

See video below.

Rear Turn Signals Double As Brake Lights

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Kisan SignalMinder w/ LED Turn Signals

In order to run LED turn signals, I replaced the flasher relay with a Kisan SM-6 SignalMinder.  The SignalMinder has a timed auto-cancel that is paused when the brakes are applied. It also allows you to turn off each side's turn signal by hitting the turn signal button a second time. (But the cancel button also still works.)

Radiantz LED Mirror Turn Signals

For better visibility of turn signals in traffic, I added 10 LED pods from Radianz to the outside of each mirror. They're pretty bright even when it's sunny out.

LEDified Side Reflectors

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LED License Plate Bolts

To be legal, a motorcycle's license plate needs to be illuminated by white light. However, if you install a white tail light in a K bike's

Cosmetic/Miscellaneous

K1100RS Fairing And Side Covers

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K1100RS Stainless Steel Grills

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K1100RS Mirror Extenders

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K1100RS Mirror Leashes

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Line-X'd Parts

I had several professionally coated in Line-X truck bad liner. It's incredibly tough. I had the following parts coated in Line-X:

K1100 Center Stand

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Additional Engine Insulation

In to cut down on the typical K bike engine heat getting to the legs,

Front And Read Fender Extenders

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Fork Protectors

TeTraxxion Dynamics Fork Guardsxt.

Tank Knee Pads

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Chrome OEM Tail Rack

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DGZRS Badge

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Metal License Plate Frame

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Stainless Steel Hardware

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L-Jetronic Mud Guard

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Ceramic Coated Exhaust Headers

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Ceramic Coated Exhaust Heat Shield

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BMW "Stealth"

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Fluids/Filters

Moly Spline Lube

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Aluminum Oil Filler Cap

From RCI Products.

Mobil 1 Synthetic Engine Oil

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Bosch Oil Filter

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Royal Purple 75W-140 Synthetic Gear Oil In Transmission

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Mobil 1 75W-90 Synthetic Gear Oil In Final Drive

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Guard Dog Moly Gear Oil Additive

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Redline Water Wetter In Cooling System

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Honda SS-8 Fork Oil

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Napa Gold 3032 Fuel Filter

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OEM Air Filter

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Seats

Corbin Gunfighter Seat

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Corbin Canyon Dual Sport Seat

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Corbin Dual Tour Seat

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Rick Mayer Custom Seat

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Luggage

OEM 22 Liter Top Case

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City Cases

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Generation Three System Cases

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Electrified OEM Tank Bag

I electrified my tank bag with an SAE socket in the front of it. I power it with a short Powerlet to SAE connector that I made to run power from the Powerlet socket in the dash pad.

I run this inside my tank bag which gives me a lot of powering/charging options:

Complete BMW OEM Toolkit

Spare Clutch & Throttle Cables

I also carry spare cables - just in case.

Factory Specifications

 

Start of Production	1985
End of Production	1995
Number Produced	18,649
Engine
Motor Type		Four-stroke horizontal three cylinder in-line engine, liquid cooled
Bore x Stroke		67 x 70 mm (2.63 x 2.75 in)
Displacement		740 cc
Max Power		75 hp (55 KW) at 8,500 rpm
Max Torque		68 Nm / 50 ft lb at 6,750 rpm
Compression Ratio		11.0 : 1
Valves Per Cylinder		2
Valve Control		DOHC, using drive chain and cup tappets
Carburation System		Electronic injection, Bosch LE-Jetronic
Engine Lubricating System		Wet sump
Power Transmission
Clutch		Dry single plate
Number of Gears		5
Gear Selection		Dog type gearbox (ratchet foot lever)
Gearbox Ratios		4.50 / 2.96 / 2.30 / 1.88 / 1.67 : 1
Rear Wheel Ratio		1 : 3.20 or 1 : 3.09
Bevel/Crownwheel		10 / 32 teeth or 11 / 34 teeth
Electrical System
Ignition System		Electronic ignition, Bosch LE-Jetronic
Alternator		12 V 460 W
Starter		0.7 Kw
Spark Plugs		Bosch X 5 DC / Beru 12-5 DU
Chassis
Type of Frame		Tubular space frame, engine as load bearing component
Front wheel suspension		Telescopic fork with hydraulic shock absorber
Rear wheel suspension		BMW Monolever swinging arm
Spring Travel Front/Rear		185 / 114 mm (7.28 / 4.48 in)
Wheel Rims, Front		MTH 2.50 x 18 E
Wheel Rims, Rear		MTH 2.75 x 17 E
Tyres, Front		100/90 - 18 56 V
Tyres, Rear		130/90 - 17 68 V
Brakes, Front		Dual disc brake 285 mm / 11.22 in diameter. Brembo 2 piston caliper
Brakes, Rear		Single disc brake 285 mm / 11.22 in diameter
Dimensions/Weights
Length x Width x Height		2220 x 900 x 1340 mm (87.40 x 35.43 x 52.75 in)
Wheel Base		1516 mm / 59.68 in
Fuel Tank Capacity		21 litres /4.62 gal / 5.54 gal US
Unladen Weight with Full Tank		229 Kg / 504 lb
Max. Permissible Weight		450 Kg / 991 lb
Ground Clearance		175 mm / 6.89 in
Seat Height (Unladen)		810 mm (31.90 inches)
Fuel Consumption		4.0 litres 100 Km / 70 mpg / 59 mpg US
Top Speed		210 Kph / 130 mph
Acceleration 0 - 100 Kph/62 mph		4.7 seconds

Power Graph: