Big Bore Kit 1070cc "S" Touring

Plug & Play Kit

Siebenrock Big Bore Kit – the original: powerful, uncompromising, proven.
In 2004, Siebenrock introduced the revolutionary 1070 cc Big Bore Kit to the public for the first time at Intermot. Its innovative design — a short, weight-optimized piston combined with a 150.5 mm forged H-beam connecting rod — caused a sensation. Thanks to the extended rod geometry, the piston remains entirely within the cylinder and does not dip into the crankcase. This concept proved convincing from the very beginning and was later adopted by numerous imitators.
Today, more than two decades later, the Siebenrock BBK 1070 — equipped with the asymmetric camshaft — ranks among the most powerful and reliable plug & play conversion solutions for classic BMW 2-valve Boxer engines. With more than 100 Nm of torque, it stands as a symbol of the uncompromising combination of technical sophistication and passionate engineering.

No matter which version you choose, our Big Bore Kits guarantee enormous riding enjoyment. Promise!

1070 cc displacement, around 80 hp and massive torque figures between 90 and 116 Nm speak for themselves.

In addition to our long-proven standard version, the “Touring” variant is now also available. Featuring a slightly shorter connecting rod, it is designed for riders who prefer smooth, powerful running characteristics and even stronger low-rpm torque.

The ultimate Big Bore Kit for touring riders and long-distance travelers delivers impressive torque “right from the basement.” It convinces in every riding situation with its smooth engine operation and tolerates lower-quality fuel — up to approximately 95 octane — without detonation.

The new and improved “S” version features:
Optimized shape of the forged pistons
New 5-piece piston ring package consisting of two compression rings and a 3-piece oil control ring, with a total weight of only 22 grams
DLC-coated piston pins for increased durability and reduced friction.

Premium quality.
Small production batches.
Engineered in Germany.
Made in Italy.

Siebenrock product
Every genuine Siebenrock product carries this seal and guarantees the highest quality — consistently optimized down to the smallest detail.

Scope of delivery
All components required for installation of the kit are included:

2 cylinders (98.0 mm), Nikasil-coated
2 forged pistons with DLC-coated piston pins and C-clips
1 cylinder gasket set including 2 cylinder head gaskets, 2 valve cover gaskets, 4 pushrod tube seals, 4 small O-rings at the cylinder base
2 H-beam connecting rods (150.5 mm) with ARP bolts L 19
1 ARP socket for connecting rod bolts
1 asymmetric camshaft including complete camshaft gasket set with 1 large and 2 small timing cover gaskets, 1 crankshaft seal, 1 O-ring

Conrod bearing shel,
Art.No. 1124419
Art.No. 1124420
Art.No. 1124460
Art.No. 1124461
must be ordered seperately!

With MOT/TÜV approval and installation instruction.
Price for the set.

For the classic BMW 2-valve Boxer models
R 100, R 100CS, R 100RS, R 100RT
Monolever models R 100RS (x), R 100RT (x)
Paralever models R 100GS (x), R 100R (x).

(x) = only permitted for vehicles up to 31.3.1994.

TIP
The use of dual ignition is strongly recommended.

Information on product safety
Ready-to-install camshaft including camshaft gear and front camshaft bearing on request.