1. Engine technology

2. Model overview

3. See also

4. References

The Honda CRF series is a line of four-stroke motocross and trail motorcycles manufactured and marketed by Honda.

The CRF line was launched in 2000 as a successor to the Honda XR series. The full sized motocross bikes are equipped with liquid-cooled, single-cylinder four-stroke engines that are available from 149 cc to 449 cc. They now have dual-sport motorcycles. The more trail friendly CRF's have simple air-cooled engines, and are available from 50 cc to 230 cc. The Honda CRF450R was the first in the series, followed with the CRF250R in 2004. Further down the line, the CRF450X and CRF250X bikes emerged, both designed for mostly off-road use. They are considered among the best motorcross bikes of their class, and have been a leading seller since their introduction.^[1]

The CRF450R was CycleWorld's Best Motocrosser for a record eight consecutive years from 2002-2009.^[2]

Engine technology

The engines in these bikes use an over-square design, which means that the diameter of the cylinder is larger than the stroke of the piston. This allows for higher engine speeds and a reduction of reciprocating mass for a given displacement. Another technology that is used is short piston skirts. The "skirt" area of the piston is the portion on the side of the piston which comes into contact with the cylinder wall and aids piston stability. While the introduction of the shorter skirt on the piston helps to reduce reciprocating mass, it also leads to more "rocking" of the piston, or minute unwanted rotation of the piston around the axis of its wrist pin. This leads to more frequent maintenance intervals for the pistons, piston rings, and cylinder walls.

Model overview

Simple, air-cooled 4-stroke motorcycles. Typically, these bikes come in low-power and confidence inspiring configurations for new market entrants.

These liquid-cooled four-stroke machines were designed to be utilized purely for closed-course motorcross racing. The CRF-R lineup lacks any extra accessories; like lights and electric start (Although offered as an option on the 2017 CRF-450R).

This machine was built as a CRF-450R that was optimized for hare scramble, hard enduro, GNCC style racing. Essentially the same as the CRF-450R except offered as standard equipment an electric start, larger fuel tank, and an 18-inch rear wheel. This bike is to bridge the gap between the more mild X-model and the closed-course race style R model. (First model year: 2017)

These bikes have electric start, but are still considered race bikes, albeit for off-road rather than motocross.^[5] Differences from the R models include lighting, electric start, suspension settings, engine and exhaust tuning for more low-end torque, larger fuel tanks, and a more rugged widespread ratio transmission. Robby Bell won the San Felipe 250 in 2006, 2007 and 2008.

In 2008, the CRF230L was introduced as an entry-level dual-purpose motorcycle. It was discontinued, several years later, with the introduction of a completely redesigned dual-purpose motorcycle. Being a dual-sport motorbike, these bikes are street legal from the factory, but still have a dirt-oriented design. They have a completely different frame and engine from Honda's other CRF formats, and most other components are not shared with the other CRF(non-street-legal) motorcycles. These different components meet emissions and government road regulations. All have full lighting and electric starts. Outside of the United States, the CRF230L was marketed as the XR230L.

In April 2012, the completely redesigned dual-purpose CRF250L was launched in Japan. It shares a liquid-cooled 249 cc 4-stroke DOHC single-cylinder EFI engine with the CBR250R. It is manufactured in Thailand.^[6]

In November 2017, the new model called CRF150L was launched in Indonesia. It shares an air-cooled 149 cc 4-stroke SOHC single-cylinder EFI engine with the Verza. It is manufactured by Astra Honda Motor.^[7]

In April 2013, exactly one year after the initial launch of the CRF250L, Honda announced plans to sell a supermoto version of their dual-purpose motorcycle in Europe.^[8] The CRF250M is based on the popular dual-purpose CRF250L, with revised suspension, uprated front brake and 17-inch wheels with wider road tyres. The CRF250M adds another A2 licence-friendly machine to Honda's line-up.

See also

• Honda Motorcycle Database
• Honda Dual-Purpose Models
• XR Series
• CR Series

References

• Inevitable (song)
• Inevitably fatal illness
• I New Dada
• I. Newton
• I. Newton Evans
• Inexact differential
• Inexact differentials
• Inex-Adria Aviopromet Flight 1308
• Inex-Adria Flight 550
• In Excelsis Deo
• In Excess
• Inexcusable
• In Existence
• Inexistence
• Inexpensive
• Inexpensive Book Distribution Program
• Inexperienced Use of the Black Book
• Inexplicable, The targeted peddler
• Inexplicable, The targeted peddler (Naruto episode)
• Inexpressible Island
• In Extremis
• In extremis
• In extremis (film)
• In Extremis (play)
• Inez Baskin