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Yamaha YZ250 two-stroke

Modern folklore would lead one to believe that after Yamaha designed the 2006 YZ250, they threw away the keys to the factory. Not true. The YZ250 has been updated at regular intervals since 2006—perhaps at a glacial rate but updated nonetheless. Modern YZ250 history is carbon-dated from the 2006 model because that is when Kayaba SSS suspension was added to the package to bring the YZ250 to the forefront of the two-stroke universe; however, there were models before 2006 that played a big role in where the YZ250 is today. In 2005, Yamaha introduced its clean and simple plug-and-play aluminum frame, and in 2003 the current engine was developed

2011 YAMAHA YZ250 MOTOCROSS TEST: THE BIKE WE’D ALL BE RIDING IF THE AMA DIDN’T FAVOR FOUR-STROKES

Q: FIRST AND FOREMOST, IS THE 2011 YAMAHA YZ250 BETTER THAN THE 2010 YZ250? A: No. Although the 2011 YZ250 did get a few changes over the previous year, most of those changes were made to make it possible for Yamaha to sell the same bike in France that they do in Virginia. In the past, there have been Euro-spec and American-spec models that differ in jetting, compression and sometimes spring rates. Q: WHAT DID YAMAHA CHANGE FOR 2011? A: There were three changes from the 2010 Yamaha YZ250: (1) Silencer. …

ARE YOU READY FOR THE NEW MXA? IT’S COMING TO A NEWSSTAND NEAR YOU

Everyone has been obsessed with Ryan Dungey, and his KTM, for the last couple months. As we get closer to A1, this will only increase. MXA not only takes a close look at Dungey’s all-new race bike, but we put him on the cover from the Monster Cup. Have you ever wondered what rider earned the most points in the course of the year? Not just the most Supercross points, or the most National points, but the whole deal. The MXA wrecking crew has been keeping track of them for years. For 2011 Ryan Villopoto ea…

MXA TEAM TESTED STEAHLY 9-OUNCE YZ250 FLYWHEEL WEIGHT

WHAT IS IT? Bolt-on traction control for the 2003?2011 Yamaha YZ250 two-stroke. WHAT’S IT COST? $109.95. CONTACT? (800) 800-2363 or www.steahlyoffroad.com . WHAT STANDS OUT? Here’s a list of things that stand out with Steahly’s YZ250 9-ounce flywheel weight. (1) Moments of inertia. A two-stroke can use a lighter flywheel than a four-stroke because it fires every stroke, compared to the four-stroke’s every-other-firing pattern. Two-strokes don?t have to maintain momentum while waiting for the next explos…

ASK THE MXPERTS: IS THE ONLY PLACE TO SAVE WEIGHT BETWEEN A TWO-STROKE AND A FOUR-STROKE IN THE ENGINE?

Dear MXA,       MXA said that the only place to save weight between a two-stroke and a four-stroke is in the engine. If this is true, how can Yamaha build a 250cc four-stroke that is five pounds lighter than their 250 two-stroke (at least according to Yamaha’s brochures)?        The answer is self evident. The YZ250F four-stroke is technically classified as a 125 and as such runs narrower a 1.85-inch rear rim (the YZ250 uses a 2.15-inch rim), a 100/100 r…

YAMAHA TWO-STROKE MOTOCROSS KIT: TURN YOUR YZ125/250 INTO A YZ250F LOOK-A-LIKE

The major pieces that had to be built special for the kit are the new gas tank, subframe and front fender (with mounting holes that fit the stock clamps). Many of the other parts are from a Yamaha YZ250F or aftermarket companies. VdLaar Racing is located in the “SoCal of Western Europe” (with a high concentration of motocross tracks, race shops, trainers and riders). Within a 40-mile range are Twin Air, WP suspension, VHM, Putoline and the Valkenswaard, Lierop and Lommel GP tracks. VdLaar Racing is owne…

2012 NEW MOTOCROSS BIKE BUYERS GUIDE: THE 2012 YAMAHA TWO-STROKES: YZ125 & YZ250

2012 YAMAHA YZ250 Yamaha won its first World Motocross Championship back in 1973?with the original YZ250 two-stroke. Today, featuring a lightweight, long-stroke engine that delivers an instant hit of free-revving power, the YZ250 is still the ultimate two-stroke race bike. (MXA note: Yamaha will not be releasing the 2012 bikes until September. The two-strokes will be included in the American lineup and, while these are official Yamaha photos of the 2012 YZ250 and YZ125, the American branch of Yamaha wil…

ASK THE MXPERTS: WHY DOES WATER WEEP FROM UNDER MY WATER PUMP?

Dear MXA,    I have a 2006 YZ250. When I fired the bike I noticed coolant leaking in a very small amount from a small hole in the bottom of the water pump cover. It didn’t leak much but I could find no reference in the manual about this. It never did this before. The hole looks like a small bolt or something might have fallen out of it. What is this and can I ride the bike? Do not try to put a bolt in the hole and do not ride the bike. The small hole between the water pump and oil seal is a we…

ASK THE MXPERTS: MY 2006 YZ250 HAS A PERSISTENT YZ250 PING; WHAT CAN I DO?

Dear MXA,     My 2006 Yamaha YZ250 has stock jetting, lower gearing and a Pro Circuit pipe, but it pings under a load. What is the solution? You have two simple solutions: (1) Add a small amount of race gas to your pump gas (which you must be running since your YZ250 is pinging). Don’t run 100 percent race gas, just add one gallon of VP Racing C12 to four gallons of pump gas. That should fix your pinging problems. (2) Even cheaper, you can change the stock N3EJ needle for N3EW (the N3EW n…

AMA RULE OF THE WEEK: WHERE ART THOU, TRACTION CONTROL?

The following AMA rule is so poorly written that it doesn’t actually ban much of anything. Read it carefully. Part 1.14 a says that “electronic devices specifically designed for traction control are prohibited.” Does that mean that an electronic device that monitors fuel and the ignition and also has traction control would be legal? After all, it isn’t specifically designed for traction control? The second half of part a says that “This includes sensors that can determine front wheel speed, and any elec…

YOU ASKED FOR IT! MOTOCROSS ACTION’S TWO-STROKE VERSUS FOUR-STROKE SHOOTOUT: YAMAHA YZ250 VERSUS YAMAHA YZ250F

The two-stroke versus four-stroke question comes up at regular intervals’so, we are rerunning our shootout to add clarity to the arguments.     Let’s cut through the effluvia! Rules changes made the four-stroke what it is today. It didn’t get there by virtue of its power per cubic centimeter, power per pound or power per dollar. Nope! Without the AMA four-stroke exemption rule of 1998, the modern four-stroke would still be defined by the Honda XR600. Forget about EPA rules (they don?t aff…

REAL TESTS! 2010 MXA RACE TEST OF THE 2010 YAMAHA YZ250

Q:  FIRST AND FOREMOST, IS THE 2010 YAMAHA YZ250 BETTER THAN THE 2009 YZ250? A: No. It is identical to last year’s model. Well, not identical, because there were two changes from 2009 to 2010:   (1) The right-side gas tank graphics are new. (2) The left-side gas tank graphics are new. Q: HOW CAN YAMAHA GET AWAY WITH  NOT MAKING ANY CHANGES TO THE 2010 YZ250? A: They can ?get away? with not changing the 2010 YZ250 because it is as close to perfect as a showroom stock motorcycle can get. Q:…

WE BUILD AN L.A. SLEEVE YAMAHA YZ270:

If you own a 2006 to 2010 Yamaha YZ250, consider yourself lucky. You have one of the best motocross bikes ever made. It weighs less than a comparable four-stroke, costs less to repair and produces more horsepower per cc. And most importantly, it comes stock with Kayaba SSS suspension. It is a sweet motocross machine. However, there is a but. If you are racing your YZ250 against 250cc four-strokes, you have a superior motocross machine; but if you race the 450 class on your YZ250, you are giving up a bun…

FIRST LOOK! THE 2011 YAMAHA MOTOCROSS BIKES; YZ450F, YZ250F, YZ250, YZ125 & YZ85

Yamaha has not officially released photo of the 2011 Yamaha motocross bikes, but MXA ‘s buddies in England were kind enough to send us the photos that they received from the European distributor. Don’t get us wrong, these are not official Yamaha USA photos, but they are the real deal. All the tech info is to the Euro spec. 2011 YZ450F: Red and white. The left side of the 2011 YZ450F. The right side of the 2011 YZ450F. 2011 YZ450F: Blue and white (with the exception of the red & white YZ450 all the A…

2009 Yamaha YZ250 Two-Stroke; Suspension Settings, Jetting Specs, Likes & Dislikes, Plus Much More

MXA’S 2009 YAMAHA YZ250 TEST     How stupid are we? Don?t answer that. Instead, let’s analyze the facts and, if possible, fix the blame on someone other than ourselves. MXA’s first choice is always the AMA when it comes to looking for a scapegoat, followed by the government, manufacturers, marketing men, and if all else fails?the Eskimos.      What’s the problem? The problem is that somehow we went from racing technologically advanced, cheap and easy-to-maintain two-strokes…

Yamaha’s 2009 YZ250 and YZ125 Intro: The MXA Wrecking Crew Meets The Wolfman

TESTING THE ONLY JAPANESE BUILT TWO-STROKES ON A VERY SPECIAL TRACK Yamaha is the last Japanese manufacturer to make 125cc and 250cc two-strokes for the American market. It is fact that they are proud of. Yamaha is quick to point out that their two-strokes share all the same components as their four-strokes, are ten pounds lighter, easier to maintain, fun to ride and retail for up to $750 less than their comparable four-stroke brethren. John Minert roosts his way under the awning of an enormous oak tree…

2009 YAMAHA YZ250 TWO-STROKE SPECS

Key Features: Our legendary two-stroke Supercross winner is more potent than ever. A light, aluminum frame housing a patented YPVS Power valve-equipped ripper of an engine results in an awesome power-to-weight ratio. Ready to race out of the crate, complete with a ProTaper aluminum handlebar, titanium footpegs, gripper seat and Excel rims. New for 2009: Dunlop D742A front tire has an innovative knob pattern for excellent grip and handling. New seat cover has great grip and more durability, and it is eas…

2008 RACE TEST YAMAHA YZ125

There will come a time when every manufacturer, race promoter, rider and AMA functionary will rue the day that the AMA allowed 250cc four-strokes to compete against 125cc two-strokes (not to mention the stupid unleaded gas rule that administered the coup de grace to the 125 two-stroke on the AMA circuit). We will all miss the 125 two-stroke when it’s gone. And, unless you are a uniquely independent individual, you probably have no intention of buying a 2008 Yamaha YZ125. You may think that the MXA wreck…

250 TWO STROKE SHOOTOUT: YZ250 versus RM250 versus 250SX

  My, how the mighty have fallen. Many years ago, an MXA 250 two-stroke shootout would have included bikes from Honda, Yamaha, Suzuki, CZ, Kawasaki, KTM, Husqvarna, Maico and Bultaco. Today, modern motocrossers only have three 250cc two-stroke choices (and one of those players has announced that 2008 is their last year in the class). Many racers have given up on two-strokes, but not the MXA wrecking crew. We grew up on them, and while we see the writing on the wall, we don’t want to go down without…

MXA BIKE TEST: 2007 YZ250

The truth about 250cc two-strokes is that they are wonderful pieces of racing machinerytechnically advanced, lightweight, blazing fast, cheap to maintain, and capable of being worked on with backyard tools. All of that is undeniableas is the fact that the modern motocross two-stroke can be found in the encyclopedia right next to the now-extinct dodo bird. Of the four Japanese manufacturers, Yamaha is in the catbird seat when it comes to two-strokes. They own the two-stroke market. When they introduced t…

2007 YAMAHAS

YZ450F New for 2007: Replacing the upper cast triple clamp with a light and strong forging, slightly reducing steering head rigidity, and the use of lighter outer fork tubes; lighter wheel rims and light wave-type brake rotors add up to super-accurate, super-responsive steering. Increasing the length of the rear shock by 1.5mm further sharpens handling. Replacing steel damping adjusters with aluminum ones removes even more weight from the four-way adjustable, titanium-sprung rear suspension unit. A more…

2004 YAMAHA PHOTOS AND SPECS-

2004 YAMAHA YZ125 What’s new on the 04 YZ125? 1. The shape of the scavenging port and exhaust port is changed (the timing is also revised) 2. The setting on the YPVS governor spring is changed for better acceleration in the low to mid. 3. The carb setting at the bypass port is changed. 4. The exhaust pipe is increased in overall length by 5mm, mostly at the head pipe (not on European models). 6. The diameter of the stinger is increased 1.6mm (in front of the silencer) 7. The shift pedal is downsized 9mm…

MXA’S SECRET JETTING SPECS, 2003 And Back

We can’t tell you how to jet your bike. It’s a big world out there (and we don’t know you all that well). However, we can tell you what jetting we run in the MXA test fleet. Take into account that we race in a Mediterranean climate, near sea level, within sight of palm trees and never far from a Double Latte. We also run fresh 92-octane gas, work on our bikes every week, clean the filters, change pistons and rings regularly, are alert to pinging and haven’t changed oil brands in over a decade. This is t…