This is where the magic happens.

Two bikes become one. Old parts meet new parts. And a K75C becomes something BMW never built — but should have.

⭐ Step 1 — Engine + Gearbox In

The 8k‑mile S engine slid into the C frame like it belonged there.

Because it does.

All K75 engines share the same mounts and engineering basics — but the S engine brought:

• lower mileage
• tighter tolerances

The gearbox I took off to lube the splines and clutch splines while I’m at it… that’s the next 30k sorted. The splines were freshly lubed. Everything aligned like a factory build.

⭐ Step 2 — The Rear End

The 17″ disc rear wheel and 2.91 final drive transformed the bike instantly. I initially put the 18 inch Drum wheel on, but then had a re-think, why wouldn’t I upgrade this too and keep a matching 8k drive train.

This setup gives:

• smoother cruising
• lower revs
• better steering, more stability, lower back end.
• better tyres – Bridgstones
• better braking – rear disc
• better geometry – 17 inch at the back

It’s the best rear end BMW ever put on a K75 without going into K1100 territory

⭐ Step 3 — The Front End

The RT forks went on next, a rusty mudguard bolt stalled me, but a drill and some WD40 sorted that

Compared to the C forks, they’re:

• stiffer
• stronger
• better damped
• better under braking
• better for two‑up
• better for modern tyres

With fresh oil and new pads, they felt brand new.

⭐ Step 4 — The Finishing Touches

• Fresh fluid – coolant and anti freeze
• Everything torqued to spec

And then…

The first start.

⭐ The Result: A K75 That Shouldn’t Exist

It fired instantly. Settled into a perfect idle. Smooth. Quiet. Balanced.

On the road?

A revelation.

• C lightness
• S dynamics
• RT stability
• Modern tyres
• Perfect braking
• Better RT cooling – though the C cowl won’t fit
• Perfect gearing
• A drivetrain with 8,000 miles
• A chassis with a new lease of life

This is the K75 BMW should have made.

And now it exists.