Chain Case Tensioning

Tech Shorts September 25, 2004 1
Chaincase Chain Tensioning So, when was the last time you checked the tension of the chain in your chaincase? Unless you ride an Arctic...

Chaincase Chain Tensioning
So, when was the last time you checked the tension of the chain in your chaincase? Unless you ride an Arctic Cat, you’d better be saying something like 500 miles ago, or so. Big power sleds need more frequent attention, and if you ever put your sled into the air this becomes even more critical. Loose chains don’t like the shock load input from a spinning track that lands hard on the ground with a spike in load feedback through the drive train.
Most Arctic Cats have a spring loaded auto-tensioner that does a pretty good job at keeping the chain tensioned properly, but this can lead to complacency in performing inspections and changing the oil. On Yamaha and Polaris models you need to loosen the locking nut on the adjuster bolt protruding out of the front side of the chaincase and tighten it by HAND, then back off about 1/8 turn. Hold the bolt head in this exact position and tighten the lock nut to maintain this setting. Don’t reef on it, just snug it up with your fingers and back it off slightly.
On most Ski-Doo models there is no lock nut, and the adjuster is on the backside of the chaincase, making it far easier to get at in most cases. Remove the locking pin (key) and again, tighten by hand (with your fingers, NO tools). Back off just until the holes line up in the bolt so you can get the pin back in. If the holes line up really close to the point you end up when finger tightening, you need to make a judgment call. You need to back the bolt off slightly from “finger tight” before locking it with the pin. If the holes line up but you can’t back it off at all, don’t put the pin in. This is worse than going 1/2 rotation out to get it in. That amount of slack is far better than being too tight.
Main thing is to not ignore your chaincase. The cover should be removed at least once a year, preferably at the end of a season, for an actual inspection. Bolts and nuts can and do come loose, and gears do chip and chain plates come loose. All of the contaminants need to be removed, so an oil change is always welcome at this time. Normally you don’t want to mix different types of chaincase lube, but stick with a name brand product here.
Since you’re in here, there are usually some serious weight savings to be gained by replacing the cheap, heavy OEM gears with some high quality ones from EPI (Erlandson Performance). EPI’s Pro Lite sprockets reduce the rotating weight of the gear by about 30%. For example, a Pro Lite 41 tooth gear can reduce the rotating mass by 3 1/2 pounds! The performance potential of this change alone is similar to something like 25 pounds! That’s how much energy it takes to accelerate rotating mass!

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