|
Three
technological gains gave rise to today's improved sleds
|
In 1960, Edgar Hetteen, one of the founders of Polaris Industries
Inc., drove one of the first snowmachines 1,200 miles from
Bethel to Fairbanks to prove the new machine was a feasible
method of transportation. Below, Hetteen is shown riding one
of Polaris' current models in Medina, Minn. (Photo courtesy
of Polaris Industries Inc.)
|
The particulars of the snowmobile's evolution in the past few years
are hard to pin down, but there have been some key advances that have
made the machines more carlike.
"It's really tough to put your finger on one crucial item," said
Jim Wilke of Anchorage's Alaska Power Sports. "But if I had to put
my finger on anything there would be three things."
No. 1:
Lighter engines with good carburators and ignition systems
A pair of Japanese companies, Yamaha and Fuji, pioneered these
engines. They transferred what they knew about making lightweight,
high-horsepower engines for motorcycles into snowmobile engines.
Heavy, cast-iron engines quickly gave way to lighter aluminum
engines, said David Johnson, a pioneer in snowmobile design. Because
aluminum transferred heat more efficiently, designers were able
to eliminate cooling fans that made snowmobile engines heavier while
sucking off horsepower.
The Japanese builders also introduced:
- Mikuni slide carburators, which efficiently fed fuel to the
engine in all sorts of conditions;
- Capacitor discharge (CD) ignition systems to reliably tell
spark plugs when to fire without the constant adjustments and
occasional failures that had been the norm with points and condensers;
- Oil-injection units that replaced hand-mixed fuel with an oil-and-gas
mixture determined by the engine itself; and.
- Exhaust systems that worked on two-cycle engines in much the
way turbochargers perform on the four-cycle engines in an automobile.
Two-cycle snowmobile engines - unlike the engine in your car -
lack valves to regulate the flow of fuel into the cylinders and
the flow of exhaust out of the cylinders. On a snowmobile, those
functions are handled by "ports" in the cylinder walls that open
and close as the pistons move up and down.
Tuned exhausts radically boosted engine power by using exhaust
gases to increase compression in the cylinder. What had been a moderate
explosion of gas and oil in the cylinder to drive the piston downward
to turn the crank became a big explosion.
Once found only on racing machines, tuned exhausts are now standard
on all snowmobiles. They have played a big role in boosting average
horsepower output from the teens and 20s into the 80s, 90s and 100s.
Some snowmobile engines now deliver close to a half-horsepower
per pound. At 100 horsepower and up, many match the output of the
engine in a compact car at less than half the weight of the auto's
power plant.
When this sort of horsepower is coupled to a lightweight aluminum
chassis to produce a snowmobile with a total weight of only 400
to 600 pounds, the rider is looking at something more akin to a
motorcycle than a car. Throttle and brake response has become nearly
as reliable as a motorcycle, too.
No. 2:
Good injection oils
Improved injection oils, and automatic oil injection systems,
helped do away with the burnt rings and blown cylinder heads that
used to kill snowmobiles after a few thousand miles.
Justin Esmailka, a Kaltag snowmobiler, said that doesn't happen
anymore. He put 15,000 miles on his 1995 Polaris three-cylinder
engine without any significant problems.
"I never took the carbs off that thing one time," he said. "I
changed one head gasket. I was on my third track."
His new Polaris twin cylinders are doing almost as well, he added,
and that's a big change from the old days.
"As kids, teens, we had all these (Ski-Doo) Olympic 340s," he
said. "We swapped engines. That was the first big motors we had
ever driven."
When the Ski-Doos ran, they ran fine. But they didn't always run.
Part of the reason why was the lower quality oil and the lack of
automatic injection. Engines that didn't get enough oil overheated
and burned up. Engines that got too much oil gummed up.
Maintenance was a constant requirement. The problem wouldn't be
solved until oil injection and better oils came along.
No. 3:
Rubber improvements
Improvements in rubber compounds meant better drive belts and
tracks. No longer do snowmobilers have to replace the drive belt
after a few hundred miles. No longer do tracks regularly wear out
or pull apart.
"Rubber track, of course, was another big change," said Johnson,
the designer. "We've come a long way in 40 years."
When he first started working with snowmobiles, the tracks - instead
of being all rubber - comprised strips of rubber-coated fabric held
together with track-wide steel cleats. The cleats were deadly on
slick trails. Once a snowmobile got going sideways on such trail,
it was essentially sliding on the equivalent of skate blades.
Usually, the machine would slide until the cleats hit something
that stopped them. Then, the snowmobile rolled. Rubber tracks solved
that problem.
Changes like that are noticeable and easy to catalog, but the
most important evolution of the snowmobile is in much smaller details
that have increasingly made the machines able to go places they
never went before while providing the rider a new-found comfort.
Five years ago, Wilke said, he rode a snowmobile from Wasilla
to Nome, got off and could barely walk. Now, when he is older and
should be physically weaker due to the tolls of age, he can ride
a snowmobile to Nome and get off feeling good.
So good, he said, that he would be quite happy to get on the machine
the next day and ride some more. This is much the same thing that
the 77-year-old Johnson said after covering more than a 1,000 miles
of Alaska by snowmobile this year.
"The machine," Wilke said, "is that much better."
©2000
Anchorage Daily News
|
