Big Bore Kit for your BMW R100 models

With a Big Bore Kit, you increase the displacement and performance of your classic BMW two-valve boxer engine while achieving a noticeably stronger torque output and improved riding feel. For models such as the BMW R100GS, BMW R100GS Paris Dakar, BMW R100R, BMW R100RS Classic or BMW R100RT Classic, Hornig offers various Big Bore Kit versions and matching components specifically developed for these motorcycles from model year 1981 onwards.

 

Big Bore Kit variants – Standard, Touring & Performance

In the Big Bore category, you will find different kits to increase the performance of your R100 engine. These include the Big Bore Kit 1070cc STANDARD, which delivers powerful performance through larger pistons and optimized compression. Also available is the Big Bore Kit 1070cc TOURING, which, with slightly shorter connecting rods and a smooth torque curve, is ideal for touring riders and provides a refined yet powerful engine character.

 

Components for the Big Bore conversion

A Big Bore Kit consists not only of complete cylinders and pistons: many individual components enable the proper assembly or repair of your Big Bore engine. At Hornig, you can obtain, among other things, the 98mm cylinder as a replacement part specifically developed for Big Bore applications, robust connecting rods in various lengths (STANDARD or TOURING), as well as matching pistons 98.000×60.650mm with piston rings. In addition, installation aids such as the cylinder gasket set, 3/8 inch socket SW, connecting rod bolts ARP L19 or connecting rod bolt RACING are available, as well as C-clip pin retainers and guide sleeves for studs.

 

Function & performance increase

A Big Bore Kit increases the engine displacement – typically to around 1070 cc – and thereby delivers more power and, above all, significantly more torque in the mid and lower RPM range. Due to the larger piston surface and optimized components, suitable kits can achieve figures of around 80 hp and over 90 Nm of torque, resulting in noticeably stronger acceleration and riding dynamics compared to the standard configuration. These effects are further enhanced by asymmetrical camshafts and lighter, coated pistons.

 

Fitment & installation tips

The Big Bore Kits and individual components are designed for classic BMW R100 engines from 1981 onwards and generally fit all common R100 variants. During installation, care should be taken to properly replace all gaskets and bolts and, if necessary, implement optimizations such as adjusted ignition timing or carburetor tuning to make full use of the increased displacement and performance. Many boxer enthusiasts report in communities and workshop reports that optimized ignition, larger carburetors or a tuned exhaust system can further enhance the results of a Big Bore conversion.

 

Conclusion – More displacement, more torque, more riding enjoyment

A Big Bore Kit is one of the most effective ways to give classic BMW R100 engines a noticeably more powerful riding experience. Whether you choose a standard version, a powerful touring setup or individual components – with the right Big Bore Kit and matching installation accessories from the Hornig range, you upgrade your boxer engine technically and significantly increase both performance and engine flexibility. This upgrade is particularly interesting for riders who want stronger acceleration and improved riding stability on longer tours or who want to give classic machines a new level of dynamics.