Photo: my HPN in Erg Chebbi, east Morocco, 1995. Visible extra equipment: sidebag carrier, luggage rack, leather topcase, tank bag.
HPN - BMW. The original replica. Four-time winner of the Paris-Dakar rally
Type:
Two-cylinder enduro with the double-loop tubular frame from the R80G/S. Special steel, reinforced at various joints, in the steering head area and rear (mine has frame number 6; to date over 200 have been built by HPN). The frame is extremely stiff and durable. Special extended (10cm./4 in.) double-arm pivoting swingarms with adjustable progressive White Power (WP) springs, spring distance 280mm/12 in. Marzocci type M1 "Paris-Dakar" front fork, spring distance 300mm/13 in. lock-to-lock fork pivot extended to 78 deg. Four-piston Brembo brakes in front, original BMW drum brake rear; tires: 90/90-21 front and up to 140/80-21 allowed. Michelin "Desert" registered in German vehicle permit. Empty/unbeladen weight, 196kg./430 lb.Power/drive:
BMW Boxer motor. Mahle special cylinders, 1043cc with shorter, lighter pistons (overall motor width is 3 cm. -- 1-1/3 in. -- narrower); 9.6:1 compression; larger valves, higher valve hub, minimum timing overlap. A double ignition system from Rudi Kallenbach. Original BMW RS stainless steel exhaust system. German "street-legal" version has 79 bhp measured at 6800 rpm. on a test dyno. (almost 90 hp measured at the brass "Enduro-Magazin" clutch). Around 50 bhp already at approx. 4000 rpm. Maximum torque of 91 Nm at 4500 rpm.; extremely wide torque band, clearly the best curve of those shown in the adjacent diagram where various tuned boxer motors were tested. Strengthened clutch (BMW K75 fork spring with special disc, etc.). Five-speed transmission with shorter 1st and longer 5th gears. Final 1:3.2 drive (on double rear swingarms, special alloy gearing). Electric and kick starter.
TABLE DESCRIPTION/NOTES:The table compares my HPN with four other special-built BMW boxer motors from Fallert, GMR, Schek and Wüdo. Bottom curves: torque in Newton-moment, top curves, bhp in DIN PS (Pferdestrke).
Note, top left: "Leistung und Drehmoment" (horsepower and torque)
Comments, right side: "The values in the table are exact values; the diagram does not allow ample room. The outstanding power curve of the HPN is clearly shown and only exceeded in the peak by the Fallert BMW. Almost all the boxers have the typical 'droop' between 4000 and 5000 rpm, with the GMR having the greatest."
Equipment:
Painted nylon-composite tank, 43 liters/11.3 gal. topped off, with 3 liter (3/4 gal. reserve. Average street range, 680 km./410 mi. (550 - 750 km.). Extra comfortable 20-cm./8-in. thick special foam, leather covered. Seat height is 1 m./39 in.!. Impact-proof, wedge-shaped special-plate oilpan. White, powder-coated, corrosion-proof frame. All stainless-steel DIN A4 bolts. HPN Cockpit fixed to frame with BMW K100 windshield and 180mm Bosch H4 (K100) headlamp. Instruments: Speedometer, larger tachometer (R80ST), clock, voltmeter, oil temperature and oil pressure gauges, ambient air temperature (digital), two on-board Sigma computers for various functions, gasoline flow meter (my own creation), satellite navigation (my new Garmin GPS III, or functionally similar Garmins can be used), "self-generated-field" -compensated compass (shaft-mounted and lighted). Heated grips, wider handguards, security alarm, triple-strength horn, and telephone with its own charger. As long-trip equipment, tip-proof aluminum luggage carrier with welded 52-liter watertight baggage boxes. I built the machine myself from original parts; as of fall, 1997 it has run over 188,000 km. (117,000 mi.) and has a "no sale" guarantee. Here are a few details about the changes (original text courtesy of HPN).
Addresses:
HPN Motorradtechnik, Hofmarkstr. 1, Seibersdorf, Tel. (08571) 5300, Fax 1081, Email: info@hpn.de, there's a new 1998 catalog.
The HPN Forum. Meeting point for HPN riders and those who would like to be. Knowledgeably moderated by Markus Kraus, now onboard at HPN.
HPN Motorcycle Technology Markus Kraus' old site, who following his studies again works at HPN taking care of Internet matters.
The following page reminds me of my own rebuilding efforts: my friend Michael Reins' HPN rebuild pages.
There are other HPN riders on the Internet — here are a few.
The HPN Team and their latest ideas.