It’s really hard to keep your hand off of full throttle when riding a brand-new snowmobile. You just paid a bunch of bucks for that high-performance sled and you want to feel what it can do to stimulate your senses. But is it safe to squeeze the throttle to the bar?
Through the years, there have been owners who say, “Just ride the heck out of it like you always do and it will be just fine.” Well, if you ride it like that, you’ll be taking your chances. When it comes to a snowmobile, there are two components that certainly need a break-in period: the engine and the drive belt.
In the case of the belt, it’s a matter of cleaning both pulleys of the preservatives that have been sprayed on them for protection in the shipping crates. With the engine, it requires more time and a well-disciplined throttle thumb.
300 Miles, Or Up To 10 Hours
The manufacturers know what works best for their machines and they tell you about it in the owner’s manual. There’s a lot of debate about how you should break in a new snowmobile, and each manufacturer has somewhat different procedures noted in its manuals on how to do it.
Some engine management computers are mapped to keep the operator from extracting full power during the break-in period. The systems retard the ignition timing and enrich the fuel delivery for a prescribed amount of time before allowing the engine to perform at its peak.
The major break-in period for most sleds is considered 300 miles, or six to 10 hours. The piston rings seating with the cylinder bore is the major concern with the first period of use for any engine. During that break-in time, avoid jackrabbit starts, but constantly vary the engine speed.
Cylinder pressure is what forces the piston rings against the bore of the cylinder to knock down the high spots on the bore and rings. High cylinder pressures allow the rings to seat more quickly with the bore, which means high throttle positions can be used during the break-in period; just don’t hold the throttle wide open for more than a few seconds at a time. Conversely, putzing along at slow speeds will not allow the rings to seat properly.
If the rings aren’t seated correctly, cylinder pressure that’s supposed to be trapped between the piston dome and cylinder head will blow between the rings and cylinder for the life of the engine, resulting in less peak horsepower. Joe Average might not notice a performance difference, but inspection after at least 1,000 miles would reveal the piston skirts are discolored brown and black.
The only things that need break-in on a two-stroke are the cylinder bores, pistons and piston rings. In the case of two-strokes, Environmental Protection Agency emissions limits have forced manufacturers to reduce oil delivery rates as low as possible. In most cases, the sled manufacturers want you to increase oil delivery by adding some oil to the first full tank of fuel.
In the case of a four-stroke, the cam needs to turn along with the followers. The pistons, cylinders and rings also need some movement before full load — for a sustained period — is applied against them. Most engines use anti-friction bearings (ball, roller or needle bearings), but a few of the four-strokes continue to use flat bearings, which require some break-in, too.
Yamaha wants its four-strokes to be idled for 15 minutes before they are ridden. During break-in, however, engine overheating is a concern and must be avoided on all makes and models. To break in the engine during the summer months with ambient temperatures around 75 degrees F, the engine can be idled for three, five-minute periods with cooling periods between. Whether new or old, all engines must be warmed up to avoid cold seizures, especially two-strokes.
Clutches, Track And Belt
Preservatives are designed to protect the surfaces of the clutches for several years, those years without use and the resulting storage periods. During pre-delivery of the machines, dealers should remove those preservatives using acetone, but not all of them do. When you get your new snowmobile, clean the pulleys yourself, and wipe the belt with solvent, too.
The belt shouldn’t see full power right away and should be used with only partial throttle for at least two hours. Drive belts are well made and quite expensive, so you don’t want to abuse them and shorten their life span. Don’t get on the throttle right away and burn notches into the belt. That initial part-throttle use will allow the engine to loosen up, as well as the belt.
Tracks today use Kevlar and other aramid fibers for reinforcement. These fibers don’t stretch and don’t really need break-in. The drive lugs and drive sprockets will seat with each other and the track may require an adjustment after some use, so keep an eye on the tension, but otherwise they don’t need a formal break-in.
Some people say that you need to put 100 miles on a track before you stud it. That’s just not true. Most race sleds are studded before the tracks have ever turned. Just make sure it’s tensioned and aligned properly as you click the first miles on the sled.
When it comes to the suspension and steering, a break-in really isn’t needed for those systems, either. A good hard pounding will loosen them up faster than a leisurely tour down a trail.