Two-stroke engine targets many applications - 2 Stroke International introduces the model 690 L-70 gasoline engine

The 1995 merger between the Cuyuna Engine Co., Crosby, Minn., and the AMW Engine Co., Spartanburg, S.C., led to the creation of 2 Stroke International (2si), and its new manufacturing complex located in Beaufort, S.C. The merger brought together the combined experiences and design ideas of the two companies, which recently resulted in the introduction of a two-stroke gasoline engine targeted at a variety of applications. The model 690 L-70 engine is rated 70 hp at 6250 rpm.

"We do two-strokes because we believe there is still a large market for them where high power density is required and weight is an issue," said Jim Davey, 2si's president and general manager. Added Andy Allen, chief engineer, 2si, "We're convinced that two-stokes can rise to meet the challenges of emissions and fuel consumption.

"The 690 L-70 engine, in the form that it's in right now, is just a plain vanilla two-stroke, simply a traditional homogeneous charged two-cycle engine," Allen continued. "So it's not something that is going to be any better or any worse than any other traditional two-strokeBut it is a platform that we can build a lot of things on in the future, starting with electronic fuel management, which is now running on our dynamometer. 2si is currently working on technologies that will allow our engines to operate on a variety of fuels, including kerosene and diesel fuel. These same technologies are also the key to low emissions and low fuel consumption."

The 690 L-70 engine has a bore x stroke of 69.5 x 60.0 mm and an overall displacement of 683 cc. It utilizes liquid cooling, electric start and a 150 watt charging system supplied by Phblon. Spark is provided by a Phblon solid-state capacitive discharge (CDI) ignition system which utilizes three independent coil/control modules, also supplied by Phblon.

The fuel system for the 690 L-70 engine has two options depending on the specific application. A Mikuni impulse fuel pump is utilized for marine, industrial and military applications, while three slide-type carburetors, supplied by Bing, are installed for light aircraft applications. The engine features cast iron cylinder liners, needle bearings in the connecting rod supplied by Ina, and SKF heavy-duty ball bearings.

"The 690 L-70 engine is really the marriage of the way Cuyuna did things and the way AMW did things, and is the first engine that was designed here," said Allen. "It was designed using many of the components that were already in production."

A GB-1 gearbox reduction drive is available for use with the 690 L-70 engine and is manufactured in-house by 2si. The reduction unit features steel alloy helical gears, with oil bath lubrication sealed in an aluminum alloy case. The gearbox is a redesign of a gearbox inherited from Cuyuna, and is available in four reduction ratios: 2.04:1, 2.48:1, 2.65:1 and 3.06:1. The modifications to the gearbox have resulted in higher load capacity and quieter operation, according to the company.