Dyno Test: Yamaha Nytro

Ready for the 120-horse snocross class
RELATED TOPICS: YAMAHA | SNOWMOBILES | ENGINES
Eagle River - We got up close and personal with the Yamaha Nytro snocross prototype at the races at Eagle River last year. We counted a new front end, exhaust, tunnel and more.
First look - This was the first glance that we got of a modified Yamaha race sled last year. It ran in Scandinavia. The obvious changes were shocks, exhaust and bars.
Nytro blasts into racing - As we await the first glimpse of Yamaha's Nytro-based snocross sled, we examine last year's evolution and Nytro's stock dyno stats!
Is it really 120 hp?
Will it run with the 600s?

Those were questions we got almost daily last year regarding the Yamaha Nytro's performance. Many consumers had doubts that Yamaha's Nytro was a true 120-hp machine. We decided to have Rich Daly at Dynoport strap one to his dyno and put a brand new Nytro through a day's testing.

The result? Nytro will certainly qualify for the 120-hp snocross class this season. Before we get to the nitty gritty, let's look at this sled's evolution.

Nytro evolves
The Nytro began as an aggressive bump-riding version of the Vector. Major changes from the Vector included standard BNG (Bold New Graphics), a taller and forward-mounted handlebar system with J-hooks and handgaurds, Pro Active CK rear suspension, Fox Float pump-adjust air shocks up front and a different clutching setup for stronger low- and mid-range pull. This was just the beginning.

Throughout the year we saw several new versions of the Nytro hit the snocross track. The first credible news we received came from Scandinavia where Yamaha was entering a snocross machine in small races in Europe. On the sled we saw a different remote reservoir shock package up front and an experimental exhaust system with only a single outlet coming out the back instead of the stock 3-1-2 exhaust.

Our next encounter with a developmental Nytro came in January at the Eagle River World Championship Derby race. There we saw another version of the Nytro hit the snocross track with rider Jesse Strege aboard. Again, we saw the single exhaust, but we also saw a lighter, more open chassis with carbon fiber body panels, reinforced tunnel with racing seat, switched out front end suspension system, including new spindle and ski set-up, stronger rear suspension, snocross ready track, flatslide carbs and more.

Our third experience with the snocross Nytro came at the WPSA finale down the road in Lake Geneva, Wis. where we saw two different Yamaha snocross sleds compete. Experienced Japanese snocross rider Yuji Nakazawa took another version of a Yamaha snocross sled - supposedly an RS Vector - around the track. We talked with his race crew and they were excited to be competing fully this year in the WPSA events. Now that Yamaha has signed championship snocross rider Robbie Malinoski, things should get even more interesting.

From a consumer viewpoint, it's no secret that racing technology translates quickly to consumer models, so we are keeping our eyes open to get a glimpse of what might be coming soon to stock models.

Dyno results
We weren't surprised to see the stock Nytro hit 120 hp at 8,400 rpm. Compare these numbers to the Vector we dynoed in December 2004, which hit 118.8 hp at 8,600 rpm. The Nytro pulled consistently stronger hp numbers at lower rpm than the Vector, but the Vector revved higher. These results are consistent with our Real World testing that showed our Vector GT wound out a little bit higher to 91 mph in the quarter mile, while the Nytro hit 89 mph.

The Nytro dyno test also was consistent with our Real World testing on the torque side. Foot-pounds were steady and strong throughout the low- and mid-range - which is where we felt the most power in our trail testing. The Nytro's top torque was 81.4 ft.-lbs. at 7,000 rpm. From that point in the power band foot-pounds began to fall, but not dramatically like you often see with 2-stroke sleds.

How does this compare to a 2-stroke with similar power? If we use Arctic Cat's F6 as a reference; the peak hp is 118.2 at 7,600 rpm. As you can see, this 2-stroke's hp peaks at a lower rpm than even the geared down 4-stroke Nytro. Torque is also relatively flat along a 4-stroke's power band, compared to a 2-stroke which ramps up quickly and falls off quickly.

Final look
We compared the Nytro extensively in our Real World Shoot-out (See Spring 2006 issue) and found it won't blow the competition away with acceleration or handling in the corners. Nytro is made for the big bumps and that's good for snocross. It also has now proven it has the ponies to be competitive, so let's hope we see some more advancement on the track this year!

Nytro test sled provided by Hygear Suspension, Lansing, N.Y., 607-533-7434.

Yamaha Nytro
973cc triple 4-stroke
RPM Horsepower Torque (ft-lbs.)
6,500 100.1 80.9
6,600 101.8 81.0
6,700 103.5 81.1
6,800 105.2 81.3
6,900 106.9 81.4
7,000 108.4 81.4
7,100 109.0 80.6
7,200 110.4 80.5
7,300 111.7 80.3
7,400 112.9 80.1
7,500 114.1 79.9
7,600 114.8 79.4
7,700 116.0 79.1
7,800 117.0 78.8
7,900 117.2 77.9
8,000 117.5 77.1
8,100 118.1 76.6
8,200 118.9 76.2
8,300 119.5 75.6
8,400 120.4 75.3
8,500 119.8 74.0
COMMENT ON THIS ARTICLE
Want to leave a comment?
Only registered members of AmSnow.com are allowed to leave comments. Registration is FREE and only takes a couple minutes.

Login or Register now.
0
Sign up for our free newsletter
By signing up you may also receive reader surveys and occasional special offers. We do not sell, rent or trade our email lists. View our Privacy Policy.

IN THE MAGAZINE