Will Honda Make 2 Strokes Again

In 1996, Honda was devoted to the 2-stroke motor. With tightening emission regulations on the horizon, the visitor invested millions in the start fuel-injected 2-stroke motorcycle. The EXP-ii project used technology that hadn't been seen before and hasn't been used since. The image was proven in the Nevada Rally and the Baja 1000. The project was later abandoned every bit iv-strokes provided a less plush solution. Here is what nosotros wrote nearly our exam ride on the EXP-two in the July 1995 issue of Dirt Bicycle.

Bruce Oglivie was ane of the main proponents of the EXP-2 project. He used spin-offs from that program to fund Honda'due south Baja efforts for years after the EXP-2 projection was canceled.

Honda is trying to save the two-stroke. The company has built a new low-emissions two-stroke that does non use lean carburetion or systems to care for the dirty exhaust. It produces less pollution because information technology uses Activated Radical Combustion, an entirely different combustion procedure that generates less pollutants. Best of all, the new engine outperforms electric current two-strokes in some respects!

The EXP-2 engine was based on the CRM250 ii-stroke dual sport, just nigh everything but the engine cases was handmade. The machine was a test bed for affordable, carbureted Activated Radical Combustion bikes.

Allow's back up a bit. The California Air Resources Lath may impose strict new emissions regulations as early as 1997 that volition utilize to bikes sold for off-road use. At the moment. closed-course machines (motocross models) are not affected past the regulations. The problem is. current two-stroke engines cannot meet the new standards. Emissions constabulary won't hunt you downwardly and take away whatsoever two-strokes you have, but manufacturers would be prohibited from selling machines that exercise not comply. This isn't  just  a problem  for Californians. The rest of the U.S.. and to some extent the world has plans to follow California'due south lead with regard to emissions regulations.

TURNING Bluish SMOKE GREEN

Conventional two-strokes are an emissions nightmare because they don't burn all of the fuel they draw in. They ship it out the frazzle. Part of the reason two-strokes are so sloppy with fuel is the odd but necessary situation of the exhaust port being open up while the cylinder is being filled with a fresh charge. Misfiring is the other problem, especially nether light loads. It happens considering ii-strokes utilise the incoming fresh accuse to push out the burned charge. Lite loads and moderate engine speeds don't go things moving well enough to prevent the fresh accuse from being mixed with unburnable exhaust. That's why conventional 2-strokes run and respond erratically unless they are working confronting a meaning load. The two-stroke'southward wasteful ways with fuel don't only create emission problems, they make for poor fuel mileage as well. Despite Honda's strong attachment to the 4-stroke engine, the two-stroke's benefits are so great that the company decided it was well worth it to make information technology work. Honda found that existing low-emissions 2-stroke engineering science was pretty lame. Conventional 2-strokes don't similar super-lean mixtures. Catalytic converters are generally beefy, heavy and expensive and don't truly solve the emissions problems. They don't practise a thing near the poor response or poor fuel economy, either. Other experimental low-emissions two-stroke engine designs employ unrealistically plush, complex gasoline injection and (brace yourself, ii-stroke fans) fifty-fifty valves!

Honda wanted a solution that took care of the emissions, response and fuel consumption bug that didn't spoil the ii-stroke's cost, weight, simplicity and power advantages. Later considerable testing, Activated Radical Combustion produced the desired results.

Activated Radical Combustion ignites the fuel-air accuse at the molecular level, non from a single bespeak as with park ignition. Combustion is faster and more complete than in a conventional engine.

BRING YOUR Dirt BIKE TO Chemistry Grade

Activated Radical Combustion sounds similar something an advertising agency would dream up, but the proper noun describes the Honda combustion process in accurate, scientific terms. The procedure itself is really non new. Managing information technology and making it truly work in a high-functioning clay bike engine is.

Activated radical combustion takes place in a 2-stroke whenever a partially burned charge comes in contact with a fresh charge at certain throttle openings and engine speeds. Many dirt bikers have seen examples of Activated Radical Combustion. It's what takes place in most engines that mysteriously run on, even when their ignitions are killed. What is happening is not "dieseling." Information technology's a complex reaction caused past the highly reactive intermediate molecules (agile radicals) left over by a previous ignition, not the direct outcome of heat or pressure.

Because combustion initiated by active radicals starts at the molecular level, it "lights" the charge from trillions of points, rather than at a spark plug way over on one stop of the combustion chamber. Because the charge literally lights from within itself, it is burned extremely quickly and uniformly. Power is generated efficiently and far less combustion heat is transferred to engine parts.

Using little more than an frazzle valve (to limit the escape of radical-rich exhaust) coordinated with the throttle, Honda has devised a system that initiates, times and sustains this bizarre combustion procedure in the lite-load range where it is most needed. Total-time conventional spark ignition takes care of starting and whatever speed range where Activated Radical Combustion isn't applied or desirable. For strong full-throttle performance, for example, the exhaust-restricting valve must be fully open up, so spark ignition does the job.

Honda'south roost-throwing, knobby-tired, rolling laboratory for the concept is the EXP-ii ("experimental two-stroke") dirt bike. Information technology is frighteningly complex with its figurer-controlled electronic fuel injection and the electrically operated exhaust valve, but Honda assured us that the electronics are only there to simplify testing, adjustment and information recording. One time the "reply volume" of throttle position-to-exhaust valve ranges and other parameters for decision-making the Activated Radical Combustion process is complete, unproblematic, affordable versions using carburetors and mechanical exhaust valves will be applied.

RIDING INTO THE Future

Then, what is it like to ride? It's weird, only even the most normal rally bikes are weird. Huge tanks, 115-mph gearing and road race-top-end engine tuning isn't the canton-fair-winning recipe for a fun, responsive dirt bike. As a consequence, the 402cc EXP-2 doesn't experience equally well-baked or strong as a CR250 in the midrange. The bottom-end power is like a two-stroke twin: lazy, polish and with near no engine vibration. A half-one thousand thousand-dollar bike with a counterbalancer-equipped engine should be shine. Information technology did have an eerily make clean, even pull from idle to well past 100 mph, with existent muscle way on top and no cease in sight to the revs. It also makes sounds similar a miniature Cummins Turbo Diesel at certain midrange throttle positions. No amount of low-speed riding could make the frazzle outlet moisture or even nighttime black. After riding information technology for a while in varying atmospheric condition, yous start to realize that a normal 400 two-stroke ported and geared similar the EXP-2 would be a disaster. If this is what two-strokes will become, there is something to look forward to.

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Source: https://dirtbikemagazine.com/when-honda-tried-to-save-the-2-stroke/

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