Honda intends to revive two-stroke engines with a brand-new, fuel-injected, clean-burning screamer engine.
New two-stroke engines from the huge H are depicted in front and side elevation in patents that were recently published.
Tagged with the numbers 71, 70, and 74, a fuel injection system can be seen on the illustration above. The device is tilted upwards and positioned low in the cylinder. this is done to ensure that the fuel “cone” that is launched over the second scavenger port in the cylinder when it is sprayed into the chamber as an atomized mist.
In This Article...
Why did two strokes vanish?
Because they were unable to adhere to the increasingly stringent EPA rules for automobile exhaust emissions, two-stroke engines were forced off the market. The simplicity of having only three moving parts—the crankshaft, con-rod, and piston—which made two-stroke engines appealing, was also its downfall.
What 2-stroke Honda model did Honda make last?
A Hondaracing dirt bike was the Honda CR250R. The prototype was constructed in 1971, but sales of the 1973 model “out of the box racers” to the general public did not start until late in 1972. The CR250’s final year of manufacturing was 2007, after almost 37 years of existence. 
Honda built an aluminum motocross motorcycle chassis in 1997, a first for the industry. These “first generation” steel frames were thick and robust, which marked a significant improvement over the earlier steel frames, whose early years had experienced flexibility as an issue. In an effort to prevent lean mixture preignition, the 1997-8 engines came with a redesigned stator that provided DC voltage for the new Keihin carburetor with an electronic “Power Jet” system. A rectifier/regulator and a capacitor were part of the new electrics. Although the Power Jet was no longer present, the 1999 model was nearly comparable.
The “second generation” aluminum frame for 2000 included smaller twin-spars, which reduced stiffness and improved handling. Older PJ versions were replaced by the Keihin PWK carburetor. The CDI box has an 8000 RPM cap. With the exception of a redesigned CDI box that increased the redline by 500 RPM and added two more horsepower, the 2001 model was essentially unchanged. Weather variations caused the new Mikuni TMX carburetor to behave temperamentally.
Honda ended the exceptional interchangeability that had existed from 1992 to 2001 for 2002.
A brand-new engine was introduced, replacing the centrifugally operated exhaust valve system in use since 1992 with an electronically controlled, cable-operated RC valve and switching from cylinder to engine case reed induction. The carburetor now has a TPS (Throttle Position Sensor), which is powered by a new stator. There was no ping sensor anywhere, but the ECM would now be able to delay the ignition timing to prevent preignition.
A third and final generation of the CR250 aluminum chassis, which was thinner and had superior flex characteristics, also debuted. Up until the end of this 2-stroke’s manufacture in 2007, the engine and chassis remained the same with just minor suspension and plastics modifications. The case reed engine may have the best design, but Honda never fully exploited it since four stroke engine development quickly captured the industry’s focus. The aftermarket was a necessity for many owners of the final generation of the CR250 in order to maximize that engine’s performance. The 2001 variants of the CR250, which are regarded as the greatest of the best ever made, are still enjoyed by fans.
When did Honda discontinue producing two-stroke engines?
The CR 500cc 2-Stroke dirt bike was discontinued by Honda in 2001, and the CR 85, 125, and 250cc 2-Stroke dirt bikes were discontinued by Honda in 2008. If you have ever driven a 2-stroke motorcycle, you will understand that it offers a very different, if not superior, riding experience than a 4-stroke engine.
Why did Honda discontinue the CR500?
The CR500 was only produced until 2001, after which Honda stopped making them. This was brought on by the 1993 discontinuation of the AMA 500 motocross competitions. Honda stopped paying as much attention to the CR500 because there was no longer a specific motocross race for the bike to participate in.
What causes the noisy 2-stroke engines?
Ever wonder why 2-stroke engines are consistently noisier than 4-stroke engines? It is frequently observed that the loud, odd sound that 2-stroke motorcycles make makes them easy to recognize. The cause of this is equally intriguing and enigmatic as 2-stroke engines themselves. We will attempt to thoroughly describe each of the factors that contribute to a 2-stroke engine’s noisy feature in this article.
The 2-stroke petrol engine’s fundamental design and operation are the primary causes of the loud noise it makes. The 2-stroke is distinguished by creating power in two complete crankshaft cycles as opposed to the 4-Stroke petrol engine, which produces power across four cycles. A two-stroke engine, in contrast to its four-stroke sibling, ignites at every cycle, to put it simply. This means that at a given RPM, a 2-stroke engine fires twice as often as a 4-stroke engine, creating not just nearly twice as much power and almost twice as much noise.
Why is a two stroke so quick?
There is a small amount of oil put into the fuel for 2-stroke engines. It is known as a “2-stroke because the whole cycle of intake, compression, combustion, and exhaust is performed by just one upward and downward movement of the piston. Instead of using intake or exhaust valves, scavenging ports, which are tiny holes in the cylinder wall, are utilized to suck in air and release exhaust. A 2-stroke engine produces more power than a 4-stroke engine and delivers that power more instantly since combustion occurs with each crankshaft turn. These are some of the factors that contribute to the lengthy history of 2-stroke engines being used in a wide range of motorcycle types. Since 4-stroke engines naturally have higher fuel efficiency and less exhaust smoke, however, demand for more environmentally friendly performance has increased. Yamaha only produces 2-stroke motorcycles for closed-course competition and a few models for export as of 2019. Despite this, Yamaha 2-stroke products are still widely used because of their outstanding reliability, simplicity, lightweight design, and relatively low maintenance requirements. Today, Yamaha 2-stroke snowmobiles are utilized to travel through Russia’s bitterly cold climate, while our 2-stroke outboard engines are frequently used for fishing in Africa. And a lot of motorcycle aficionados still adore 2-stroke engines for their powerful, astounding acceleration. For 4-stroke engines, there is no oil added to the fuel, and the piston moves up and down twice during each combustion cycle, therefore the name “4-stroke. However, 4-stroke engines need highly precise intake and exhaust valves, which makes this engine style more complex, heavier, and has additional drawbacks. However, they give consistent power, have good fuel economy, produce lower emissions, and more. Because of this, 4-stroke engines are found in practically all two-wheel vehicles, from large motorbikes to small scooters.
Facts About Two-Stroke Vessel Engines
- High-emission two-stroke engines are not subject to any saltwater or river limitations in California, with the exception of some local bans on personal watercraft (vessels like Jet Skis). For instance, personal watercraft are not allowed within 1200 feet of San Francisco’s shoreline. For a list of lakes, see “Local Restrictions” on our website below.
- Some lakes forbid high-emission engines because a carbureted two-stroke engine can release up to 25–30% of its fuel unburned into the atmosphere or water.
- A label sticker (with 1 to 3 stars) certifying compliance with the California Air Resources Board emission standards for vessel engine manufacturers for 2001, 2004, and 2008 will typically be present on a direct injection two-stroke engine’s engine cover.
- There is no current plan to “ban” the use of two-stroke motors on any Californian rivers.
- Two-stroke engines with electronic injection and carburetion are regarded as having high emissions. These engines were mostly produced before 1999.
- With a few caveats not linked to emission restrictions, direct injection two-stroke engines, produced since 1999, are deemed clean emission engines and may be used on any Californian body of water.
What makes the 2001 CR250 so excellent?
This Motocross Action Magazine test is from the November 2000 issue and has been archived. Purchase an MXA subscription right away.
For years, Honda’s engineers have been criticized by the MXA wrecking crew and devoted riders for systematically detuning the engine, shortening the powerband, and weakening the handling to the point that new Hondas weren’t as good as older models. Honda finally realized its error and returned to the past for the 2001 model year.
HOW DOES THE 2001 HONDA CR250 FARE?
The positive: The powerband is the best feature of the 2001 Honda. The punchy, one-dimensional, fleeting powerband of previous years is gone, and in its stead is the traditional mid-and-up rpm engine. A CR250 rider may now complete a straight by keeping the engine running rather than shifting every 25 feet. The power is more expansive, user-friendly, and burden-free.
The bad: Although it may sound sacrilegious, Honda may now think about returning to the old frame after returning to the old engine. The bike’s aluminum frame is overly inflexible, vibrates uncontrollably like a washing machine on overdrive, transmits shocks from the suspension, and is challenging to work on. Honda’s suspension is not good enough to utilize a frame design that reduces suspension performance.
What we ride in our bike while jetting is as follows: 430 Mainjet (420 stock) 30th pilot jet (35 stock) tweezers 6BEH2-75 (6BEH1-73 stock) 1.75 air screw turns (1.5 turns) Clip #2 (3rd stock).
HOW GOOD IS THE SUSPENSION?
A firmer shock spring is a must for this bike. Riders under 160 pounds can use the default 4.8 kg/mm spring rate, but everyone else will be happy with a 5.1.
Which shock setting worked best for us? 5.1 spring rate (4.8 stock) Race sag is 97mm, and the turn out is 1.25. minimal compression 9 clicks to exit Rebound 9 exits.
The forks: For 2001, Honda lowered the compression damping and switched to the next stiffest spring (0.44 kg/mm). Good move, however the forks still have a sharp mid-stroke, a dead feeling, and a propensity to hang down in their stroke (particularly for riders under 160 pounds). In order to achieve a feel we can live with, we add one 0.45 spring to slightly raise the spring rate before adjusting the oil height.
What horsepower does a CR500 have?
At $2,598 and a reported CR500 horsepower of 59 hp (43.4 kW), consumers were promised a great deal and got more than their money’s worth. The CR500 was highly praised for its power and price.