BMW K 75 RT
| BMW | |
|---|---|
 K 75 RT from 1994 in silk blue, series K569 |
|
| K 75 RT | |
| Manufacturer | BMW |
| Sales description | K 75 RT |
| Production period | 1989 to 1996 |
| class | motorcycle |
| design type | Tourer |
| Motor data | |
| In-line engine with three cylinders | |
| Displacement (cm³) | 740 |
| Power (kW / PS ) | 55/75 at 8500 min -1 |
| Torque ( N m ) | 68 Nm at 6750 min -1 |
| Top speed ( km / h) | 185 |
| transmission | 5-speed |
| drive | Cardan |
| Brakes | front Ø 285 mm double disc brakes, rear Ø 285 mm disc brake |
| Wheelbase (mm) | 1516 |
| Dimensions (L × W × H, mm): | 2230 × 916 × 1460 |
| Seat height (cm) | 81 |
| Empty weight (kg) | 258 |
| Previous model | BMW K 75 C. |
| successor | none |
The BMW K 75 RT is a touring category motorcycle that was offered from 1989 to 1996. It is the most travel-friendly variant of the BMW K 75 series, which is the only model series in the world to have a horizontal three-cylinder in- line engine . The original basis is the BMW K 75 C presented in 1985 .
description
General
The K 75 series is technically closely related to the BMW K 100 presented in 1983 with a four-cylinder in-line engine. The series was added as a smaller version two years after the four-cylinder was presented. The main technical differences between the two K series are the modified frame and the rear wheel brake - drum brake with mechanical actuation instead of disc brake with hydraulic actuation - and of course the motor.
Later models also received a disc brake in the rear wheel, which proved to be necessary at the latest with the introduction of ABS (initially available on request). The K 75 series has the only three-cylinder engine ever built by BMW for motorcycles. In principle, it is the K 100 engine, which has been shortened by one cylinder unit . The K 75 engine has a balancer shaft to eliminate the vibrations typical of three-cylinder cylinders due to incomplete mass balancing . As a result, the engine of the 75 ran even more quietly and with fewer vibrations than the four-cylinder engine of the K 100. The engine developed from 740 cm³ a nominal output of 55 kW (75 PS) at 8500 rpm. The K 75 was widely used in a special version for the police, derived from the K 75 RT, which, among other changes, has a single seat instead of a bench suitable for two people and a case behind it for the radio equipment.
The motorcycle accelerates from 0 to 100 km / h in 4.6 seconds and reaches a top speed of 185 km / h.
Details
The main feature of the K 75 RT compared to other models in the series is the large-scale full fairing , which naturally increases the weight and enlarges the frontal area and thus impairs the maximum possible driving performance, but offers the driver good wind and weather protection. Its idiosyncratic, angular shape resembles the similarly designed cladding of the BMW K 100 RT. All RT models were supplied with packing cases as standard; The same cases were only available for the simpler K models as accessories or at an additional cost. As one of the very first motorcycles, the K 75 RT was optionally available with an anti-lock braking system right from the start.
A characteristic feature of all motorcycles of the K-series is the horizontally lengthways (cylinder behind one another in the direction of travel, cylinder head on the left, crankshaft on the right), which transmits its power to the five-speed gearbox behind it in the direction of travel via an intermediate shaft and a single-disk dry clutch . For technical reasons, this unusual construction generates a whirring to howling noise, which earned the K series the nickname “vacuum cleaner”. The engine-transmission block was also used as a load-bearing component of the chassis: The rear suspension is mounted on the transmission and has no direct connection to the frame.
The three-cylinder K 75 series was withdrawn from the range in 1996. The four-cylinder series - developed from the K100 in several evolutionary steps to the K 1200 RS - was gradually replaced by the new BMW motorcycle series with a transversely installed four-cylinder in-line engine. Until 2009, the old K series with a longitudinal engine was only part of the production program in the form of the luxury tourer BMW K 1200 LT .
Further development
The reasons for abandoning the longitudinal engine concept after more than 20 years were the technical limits of this concept. A further increase in displacement beyond the last 1171 cm³ of the K 1200 could no longer be achieved, as an increase in the cylinder bore could not be accommodated in the engine block and an extension of the piston stroke was also problematic. Another fundamental - optical, not technical - disadvantage of the horizontal in-line engine is its unusual, box-like appearance, which was only noticeable in the half-clad or uncovered model versions, but did not go down well with all customers and also did not harmonize with the new style trends in motorcycle design , in which rectangular shapes are perceived as not "dynamic" enough.
Sales figures
In total, the K 75 RT was built in a number of 21,264 copies and was thus the most built model of the K 75 series.Other K-75 versions are the BMW K 75 C (basic model with small handlebar covers, built from 1985 to 1990, 9566 pieces) , the BMW K 75 S (sports version with frame-fixed half fairing, 1985–1995, 18649 pieces) and the BMW K 75 (new basic model without fairing, 1986–1996, 18485 pieces). The new prices were always at the upper end of the 750 class.
literature
- Jeremy Churchill, Penny Cox: BMW K 75 and 100. Two-valve in-line engines. (= Haynes maintenance and repair ). 1st edition. Moby Dick, Kiel 1999, ISBN 3-89595-132-3 .
Web links
- Technical data BMW K 75 RT. University of Innsbruck, archived from the original on January 13, 2007 .
- 1980s - New technology, new segment: BMW Motorrad continues to push innovations. BMW motorcycle
- The K569 project: the three-cylinder from BMW. In: flyingbrick.de. (Private website of a fan base).
- BMW K 75 RT 1995. In: Bikez.com Motorcycle Encyclopaedia. (English).
