A few weeks ago I penned a piece responding to the burning question: “How long will a 2-stroke last?”
I’ve been following your comments and there is a definitive group making impressive 4-stroke longevity claims. I’m excited to hear accounts of huge klicks amassed on many 4-stroke rides.
For the record, I would not disagree 4-stroke snowmobile engines, on average, will go more miles than a comparable output 2-stroke before needing a major overhaul. There are a lot of reasons for this but suffice it to say the reality of much larger 4-stroke displacements required to generate power comparable to a 2-stroke has something to do with the “less stressed” lives these engines are living.
For sure, the very nature of the 2-stroke versus 4-stroke argument is rooted in a pressurized oiling system on all 4-strokes (either dry or wet sump) versus a total loss oil delivery system on 2-strokes. When carefully analyzed and compared, the average 2-stroke delivers a pretty small amount of oil to critical engine parts.
This is why high performance snowmobile 2-strokes all use roller bearing crankshafts. Roller bearings can live in a low oil environment. Plain bearings? Not so much.
The inescapable reality is this: 4-strokes get better lubrication at all temperature and RPM levels. Oil is important – very important – and its abundance in any 4-stroke to 2-stroke comparison pretty much tips the scales in favor of a 4-stroke having superior longevity.
Before 2-stroke lovers send hate mail, I need to say this: The quality of today’s full synthetic 2-stroke oil has made a huge improvement in those engines’ longevity, too.
On the other side of the ledger consider this inescapable reality: The cost to maintain and the cost to rebuild a 4-stroke. Its one thing to envision your 4-stroke sled lasting 50,000 klicks (30,000 miles) but in order to get to that mileage, what was your investment? For sure, you likely paid more in the beginning for a 4-stroke powered sled.
Simply put, if you compare apples to apples, except for engine choice (2 versus 4-stroke) a 4-stroke invariably commands more jing when new. The need to perform an annual engine oil and filter change is a consideration as is a valve lash adjustment every couple seasons.
Finally, if you do crest that lofty 50,000 klick (30,000 mile) threshold and its time for a rebuild, look out! The cost to rebuild a 4-stroke will make your eyes water compared to a 2-stroke.
Am I saying a 2-stroke snowmobile engine makes more sense and is cheaper to put big miles on its odo? Nope, not at all. Here’s what I will say. Don’t keep your 4-stroke until it has tens of thousands of klicks on it.
In the same way a 2-stroke’s resale is negatively affected as the odometer climbs, so will your 4-stroke sled’s resale rise and fall with the odometer – understanding the 2-stroke will fall further.
The difference is how much use (miles) you can rack up before dipping into your wallet for a 4-stroke rebuild. That somewhat elusive number is critical in calculating the 4-stroke payback equation.