We are tuning in close discussion with our customers and if necessary fulfil the street legality requirements of the german or even swiss homologation. From the slim racing engine over the power encreasing engine overhaul to our showpeace, the HPN-boxer-engine with 75hp at 1043ccm goes the range of tuning. If necessary in a HPN or BMW street bike the engine in combination with the HPN Baja muffler fulfills the 80db noise and ECE pollution requirements.The tuning is not limited to the Mahle-cylinders and pistons, a lot of work is spent for details like sports-crankshaft, titanium conrods, special camshaft for more midrange torque and top power, head porting, double ignition, and exact definition of the compression ratio for the required use. We take the same care for your engine in case of an overhaul or repair. Of course we use modern machinery for valve seat machining. A lot of motorcycle magazines stated the vibrationless running of the HPN tuned engines and measured power.We tune the transmission and clutch of your bike as well. The clutch gets adapted with a reinforced friction plate and more pressure to the higher torque and bad running conditions in deep sand and a lot of dust. The transmission can get additional magnetos to hold back tiny steel particels; art.: 401.5 (without picture). With different gear ratios we adapt your transmission to your ideas. First gear can get a short ratio for trial passages, for touring riding we give you a long fifth gear to lower revs. and fuel consumption. We take care of your faulty transmission and modify older transmissions to the latest specs. Corroded gear boxes become like new after glass blasting treatment.
All our gears are ground after hardening process and meet closer tolerances than stock products. They are manfactured exclusively for us by a german gear manufacturer to
HPN requirements. Highly sophisticated measuring equipment assures the high HPN Quality. For prices have a look at our
1043ccm kit
HPN-1043ccm big bore kit
1043 ccm big bore kit
complete set - made in Germany (art.nr. 307) 

Comes with: Cylinders with stainless steel pushrod tubing, pistons, head gasket, shortening of your cylinder bolts and pushrods, shortened intake manifolds, adaption of the squish area of your cylinder heads, TÜV certificate. Power output depending on the compression ratio and accessory from 48 kW (68 hp) to 53 kW (75 hp), weight saving compared to 980 ccm serial parts about 1,1kg, the piston is 182g lighter than the serial part. Engine width is reduced for 26mm.

Titanium conrods
HPN-titanium conrods
Titanium conrods
for the 2-valve-boxer (art.nr. 306)

Exclusively produced for HPN by a Formula 1 supplier for Ferrari. Wheight 350g (against 620g stock) complete with bearings for the sports engine.

Transmission tuning
long 5th - short 1st gear

Long fifth gear in picture left. Ratio change 5%+. Caution: Can be installed without changes in all BMW-GS bikes produced after 4/82 (due to 17,5° angle)*. Short first gear in picture right. Ratio change -5%. art.402

*Earlier models can be changed to this much more endurable gear type, as we also produce the intermediate shaft gear with the 17,5° angle. art.:403** In this case you need addionally the input shaft gear with 17,5° angle. art.403.1**

** Please order with motorcycle type and chassis nr.

HPN-rallye oil pan
Rallye oil pan
with aluminum bottom plate (art.nr. 314)

Rallye oil pan with aluminum bottom plate avoids cracked oil pans when hitting ground or rocks. Race proofed item with a conical wheight reduced spacer ring.

for a regulated temperature of your motor oil (art.nr. 302.1)

The thermostat is adjusted to begin opening at 90°C and is fully open at 110°C. This reduces the time to reach regular temperature and makes it possible to reach this temperature at all under bad weather conditions and in the cold season.

Caution ! There are often problems based on incorrect mounted parts when changing oilfilters. Engines of the GS series 87-96 need no paper gaskets under the filter cover. If the gasket is installed you can get severe motor damage due to low oil pressure and too high oil temperature. Please follow the mounting instructions - if you are not sure ask your dealer or HPN.

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