Monday February 7, 2005
For its 2006 snowmobile product line, Yamaha launched a new four-stroke engine, 11 new models, four new suspensions and updates to most returning models. Most importantly, the very model that propelled Yamaha to the forefront of high-performance four-strokes– the RX-1– has been retired.
In its place — in a revised Deltabox chassis and powered by a new four-stroke engine — is the new Yamaha Apex available in three configurations: Apex ER, Apex GT and the Apex RTX.
The Apex models are radically improved in all areas: engine, chassis, suspension and ergonomics. The GT stands for “groomed trail” and the RTX stands for “rough trail.”
All three Apex versions share a common engine configuration in the new Genesis 150 FI. The number “150” corresponds to its horsepower class. The new engine retains the bore and stroke of its 998cc predecessor, the Genesis Extreme.
The new and old engines also have the five-valve head design in common. However, the use of lighter components, revised intake and exhaust porting, and the addition of a Bosch fuel injection system increase the output by 8 hp to a claimed 149 hp.
Engine weight was reduced by 7 pounds compared to the previous Genesis Extreme. A cooling system revision in the form of a radiator and thermostat-controlled electric fan helps ensure the engine runs at consistent temps — which Yamaha says keeps the fuel injection system performing at its best.
The new engine revs quicker thanks to a crank that is 2.3 pounds lighter. Throttle response is improved with the fuel injection system, which features Mikuni downdraft throttle bodies with Bosch electronics to provide the proper mixture, grabbing air from a new airbox that is integrated with the hood design. Intake port design changes provide the opportunity for intake and exhaust timing revisions, which required a new cam design.
Most notably, the intake timing has a longer duration. It used to open at 31 degrees before top dead center (BTDC) and close at 57 degrees after. The new design allows fuel to rush into the chamber from 33 degrees BTDC to 71 degrees after.
Exhaust port opening duration was shortened from the previous design. With the longer intake duration, the stronger power stroke empties into a new, more efficient 4 into 2 into 1 exhaust system.
The chassis for the Apex models is now called Deltabox II. The handlebars are raised and hooked, and the driver sits 6 inches more forward, compared to the Deltabox design.
It uses the same front geometry as the 2005 RS Vector. Front suspension hardware varies among the models from standard shocks on the ER to the GYT-R piggyback remote reservoir on the GT to Fox FLOAT shocks on the RTX.
The Apex RTX, for “rough trail,” is calibrated for more aggressive riders and comes from the factory with Fox FLOAT shocks.
Rear suspensions are the Mono-Shock RA, but the Apex GT has an Ohlins EC electronic shock. The shock features electronically adjustable compression, controlled on the left handlebar. It also has a clicker adjustment for rebound adjustment.
The Apex ER is a claimed 11 pounds lighter and the RTX is a claimed 14 pounds lighter than the ’05 RX-1.
The RX Warrior also disappeared this season, in favor of the new Attak. It uses the same Genesis 150 FI engine as the Apex series and adopts the same ergonomics from the Deltabox II. The Attak weighs a claimed 23 pounds less than the RX Warrior.
A version of the Mono-Shock RA is on the Attak. Rather than extend the rails and bolt it into the longer tunnel, the Attak’s version has new 136-inch rails, rear suspension arm geometry different from the short-track version and a longer control rod.
The 120 hp Class
Yamaha is hitting the popular 120 hp class with several new models with the same Genesis 120 engine it introduced in 2005.
Yamaha’s new Nytro, based on the RS Vector model, is a legitimate four-stroke ditch banger.
The new Nytro features: stand-up riding ergonomics; an optional, aggressive decal package and color scheme; and suspension calibrations to match. It will use Fox FLOAT shocks in front and a new torsion spring rear skid called the ProActive CK. This rear should offer better preload. The rear shock will be a piggyback KYB with a compression clicker.
We had the opportunity to pound this machine through a series of 2- and 3-foot moguls. The Nytro did nothing surprising, and handled the terrain admirably. Could Yamaha have produced a legitimate, four-stroke ditch banger? Based on our ride of the prototype, we think so. We’ll order ours with the skull graphics.
The other RS short track chassis changes vs. the 2005 RS Vectors are a new brake/disc combination and a magnesium chaincase cover that combine for a 2.5-pound weight loss.
The standard RS Vector will remain unchanged for 2006. It does get a sibling, though, in the Vector GT, which will be marketed to the groomed-trail rider. It will include new convenience features, such as a 12-volt accessory plug and a standard handlebar bag. The RS Vector ER will come back with the Mono-Shock RA rear suspension, a new brake and magnesium chaincase cover.
The RS Rage, with the136-inch track, now has the same rear skid as the Attak. In all, the machine is 17 pounds lighter than the 2005 version, and gets improved stopping power from a four-piston brake and new disc.
The 2-Up RS Venture touring mount has a new, taller windshield for improved protection. The easy-adjust rear suspension block changes the machine’s intent from solo to 2-Up touring and the rear seat removes easily for more solo touring cargo space.
Mountain Sled Upgrades
The RX-1 Mountain vanished from Yamaha’s mountain lineup as well, and is replaced with the Apex Mountain. It uses the same 150 FI engine as its trail counterpart, as well as other features like the updated rider position, styling and instrumentation from the Deltabox II chassis.
The key differences between the trail and mountain versions are the mountain-specific features. The floorboards are wider, the handlebars are taller and hooked for improved comfort and control. The increased floorboard area has new traction for limited slip and to avoid snow build up.
There is also a new rear mountain rack that increases storage space and offers more function. The exhaust tips are baloney cut to keep heat away from your packed lunch.
The tunnel is a new, one-piece design. Previous mountain RX chassis used the standard short-track tunnels with a riveted extension. Underneath the new tunnel is a new 16- by 162- by 2.25-inch Camoplast track. After riding the machine near Alpine, Wyoming, last month, the ergo changes and the new track make this machine more agile and capable.
The new RS Vector Mountain SE comes with the Genesis 120 engine, 16- by 162- by 2.25-inch track and a Pro Mountain 162 suspension. The sled offers increased weight transfer from previous designs.
The RS Vector Mountain returns for 2006 with a few changes. A new seat design, with storage, is taller for easier stand-up riding and to meet the new handlebar position. Taller than in 2005, the new handlebars are wider, hooked and positioned to improve mountain riding ergonomics.