Suzuki
XN85 Turbo model history
1981—1983
| I
have tried to tell the Suzuki XN 85 Turbo model history on this page
as I know it. The page is still under contruction.
I would be grateful of any contributions — sales brochures, magazine ads,
magazine articles, pictures, specs, facts, corrections etc. Please scan the material
in JPEG format (large enough that all the details are visible) and send
them to me. Please tell me the source and the publication date if possible.
If you send me pictures of your own bike, please follow these
instructions.
|
From around the end of the 1970s, turbochargers were used to improve the performance of four-wheel vehicle engines, and in the early 1980s turbo engines were also tried out for motorcycles. Along with Kawasaki's 750 Turbo and Honda CX Turbo, Suzuki brought out the XN85. The base model was the GS650G Katana, unveiled at the Cologne Motor Show in 1980.
The model name XN85 comes from its maximum output of 85ps. The naturally aspirated GS650G (for overseas markets) had 73ps, so turbocharging showed an output increase of over 115%. However, the output characteristics controlled by intake air injection were aimed at increasing torque mainly in the mid-speed range, making it easy to handle. The piston cooler and other technologies tried out on the XN85 were carried over into the later oil-cooled engine era.
|
 
1981 Suzuki year code: X
| 1981–1982 Suzuki XN85 Turbo Prototype with different graphics and visor |
In early eighties, there was a turbo boom and various Japanese manufacturers released motorcycle models equipped with turbo engines. A bolt-on turbo kit for motorcycles was already on sale in USA. When the Suzuki GS750 was released in 1977, the turbo kit was released immediately by Garrett, and the GS750 equipped with it accelerated from 0 to 400 meters in 9.35 seconds. Other companies, such as American Turbo Pack and Blake Enterprises, were selling turbo kits tailored for motorcycles.
The Japanese motorcycle manufacturers, Suzuki included, became interested in turbochargers and began research and development. Suzuki says that their development began as part of energy conservation efforts. Tha goal was to obtain more horsepower with a small power unit and to improve fuel efficiency. The displacement was determined to be 650cc, which is in the middle class, and the target value was set to have a power similar to that of a 1000cc engine. The base engine was the DOHC unit of the GS650G Katana, which was unveiled at the Cologne Motor Show in 1980.
Various problem arouse while testing the new technology. The piston heads were melting from the high temperature. Prototypes were made using forged pistons and heads made of ceramic, but more than 1,000 different types were tested before they were put into practical use. Also, the increased heat caused self-ignition of the air-fuel mixture, resulting in a knocking phenomenon. Lowering the compression ratio took care of that problem. Compression was down from a typical 9.5:1 to 7.4:1.
Also, Suzuki developed a new cooling system, later used in many Suzuki oil-cooled engines. A nozzle inside the crankcase injected oil into the piston for cooling. This oil cooling was also used to cool the exhaust side valves, valve springs, guides, and valve seats. A big oil cooler was installed under the fuel tank, with more than three quarts of oil in the system. The oil cooling system, together with air flow, kept the engine heat under control.
A lot of attention was put on durability, with upgraded components such as conrods. With the increase in power, each part was revised, such as increasing the crank diameter and connecting rod big end diameter by 2 mm to 34 mm φ, making the engine look the same as the GS650 engine, but the inside was different. The American-made turbo used in the test had a relatively large 68 mm diameter turbine, which provided more power at high revs, but for practicality, a smaller Ishikawajima-Harima turbo unit with a 50.4 mm turbine was selected. L-Jetronic electronically controlled fuel injection was adopted and matched with the turbo in an attempt to reduce turbo lag and fuel consumption. As a result, Suzuki achieved a maximum output of 85 ps @ 7,500 rpm and a maximum torque of 7.8 kg-m @ 7,500 rpm.
The suspension was designed with an emphasis on sports riding. A 16-inch tire was used at the front, and A48 tires were tested in collaboration with Michelin. The suspension was equipped with an anti-nose dive mechanism at the front, and a full floater suspension at the rear, which was not yet available on any mass-market on-road models at the time. A sportioer chain drive was used insted of a of shaft drive. |
1982 Suzuki year code: Z
Turbo models from various manufacturers were exhibited at the 1981 Tokyo Motor Show, Suzuki's turbo model being one of them. Kawasaki was exhibiting a prototype of the 750 Turbo that was released in 1984. Suzuki's XN85 (the number telling the maximum output) was released in 1982 as 1983 year's model. The model was not sold in its home country but was only made for export.
The most notably differences between the prototype shown at the 1981 Tokyo Motor Show and the production model for the 1983 season were different graphics, different rear foot pegs and their mounting,
different visor, different chainguard and different rear end of the seat. |
| 1981–1982 Prototype with slighty different graphics, chainguard and visor |
1983 Suzuki year code: D
The XN85 was a short-lived model. It was expensive to make and could not compete with the larger models in performance. The market proved suspicious of the 'new' technology If such turbo bikes were more expensive than 750cc or 1000cc bikes, it was hard to convince people to buy them. Production of the XN85 ended after 1,400 units.
Some sources on the Internet list other model years for this model but officially Suzuki manufactured only one model of the XN85, the 1983 D model, starting with the serial number GP71A-100001.
Still, the Suzuki XN85 was a not a bad bike in any means. It was the first street bike to introduce Full Floater monoshock rear suspension, oil cooled system for the engine and 16-inch front wheel. It just couldn't compete with its bigger (and cheaper) siblings without turbocharging.
|
| 1983 Suzuki XN85 Turbo, Iron Silver Metallic (15K) |
More: Suzuki
XN85 Turbo
More: All
Suzuki models
This free site is managed by Jarmo Haapamäki.
If you find this site helpful, please leave a donation for Jarmo
so you can enjoy the spirit of giving too.
Came here from a search engine?
Click at the home
button below to get to the main page with frames.
|
