Question:
Dear Motorhead,
Why does Supertrax and other magazines refer to Yamaha snowmobiles by horsepower rating instead of engine size? I know 4-strokes make less power per cc than 2-strokes, So this should be brought to a reader’s attention.
I’d also like to comment on 4 stroke longevity. I have a sport bike and a 4-stroke quad and they do smoke (more than a 2 stroke )and require expensive rebuilds such as cams, cam followers pistons, rings, valves and guides.
Eric
Response:
Thanks for your email!
Your questions are interesting and have been regularly addressed in many issues of SUPERTRAX.
With the proliferation of 4 stroke models it is actually better to compare by HP than cc as the segments line up that way as a result of established parameters. Example – the 600cc class is the 120-125 HP class – right? Yamaha’s Vector is a 120 HP sled with a 1000cc triple 4 stroke. It is priced almost dead-on with the 600 class 2 stroke traffic so that’s why we put them together and compare them.
Yes, 4 strokes are real expensive to rebuild and when they explode it hurts. However, the market impression (this has been editorialized in ST many times!) is that 4 strokes will last longer.
Under most circumstances – I wouldn’t disagree with that general assertion. However, lets say a 4 stroke will go 20,000 miles in a sled without a rebuild and a clean 2 stroke will go 10,000 miles.
I would estimate the cost to rebuild the 2 stroke twice would be very close to rebuilding the 4 stroke once. See where I’m going? In any case, 4 stroke sled engines which are not exposed to dirt and water like dirt bikes and ATV’s have proven to be exceptionally reliable.
Motorhead Mark
