Chain and Sprocket Maintenance

The Lube Job
The choice of chain lubricant is up to you; there are so many good ones it's hard to go wrong. Me? I use an industrial-strength chain-and-cable lube intended for heavy equipment that I get through a friend in the construction business, but that's 'cause I'm old and stuck in my ways.

Whether lubing the inside run of the chain allows centrifugal force to push the grease into the chain rollers or not is the subject of some argument. I believe it does-plus it makes for a neater job. If you prefer to spray the stuff all over the chain, I won't argue the point with you. In any event, using the method you prefer, jab the straw of the chain spray down into the chain, right between the side plates and the rollers, and give 'er the gas. First do one side of the chain and then the other, spraying each side at least three times.

We're talking about a full chain service here. Ninety percent of the time you're going to be lubricating the chain on the run, so to speak, and in those instances try to lube the chain when it's warm. The oil will flow more freely then, and if you can, do it after the ride so the oil has time to permeate the chain and the excess can drip off, rather than be flung off to coat you and your bike with unattractive goo.

Every so often someone tells me he doesn't see a need to lube his chain because he's got one of those O-ring jobs on there. Wrong. For those who aren't familiar with O-ring chains, here's how they work. When the chain is assembled, high-pressure grease is injected between the rollers. The roller links are then sealed by placing O-rings between them and the side plates. O-ring chains still require external lubrication, although the lube plays a slightly different role. Primarily the lubricant's job here is to keep the O-rings pliable and to displace moisture and prevent rust. So O-ring or not, the rule is keep it lubed.

It's In The Adjustment
Once and for all, chains don't stretch-that'd be just about impossible, and they'd be far more likely to snap if that much tension were applied. What happens is that friction and heat cause the chain lubricant to dissipate. This leads to metal-on-metal contact between the chain's moving parts, and it also allows dirt to filter in. As wear ensues, play develops, and pretty soon you've got a slack chain.

The first question is, when should the chain be adjusted? If you answered, "When it's loose," then you lose points for both originality and accuracy.

While there's certainly no harm in adjusting the chain the moment the slack exceeds the manufacturer's recommendation by the first millimeter, there's no good reason for it, either. The rule of thumb is that when the chain slack exceeds twice the manufacturer's recommendation it's time to adjust it. So if your owner's manual calls for 1 inch of slack and you've got an inch and a half, no worries. But if there are more than 2 inches of sag in the thing, get out the wrenches.

Ideally a chain should always be adjusted with the weight of the rider and whatever he's going to be carrying on the bike. Here's the right way:
* Rotate the wheel five or six revolutions, turning it slowly until you find the chain's tightest spot.
* With the weight of the rider (and whatever he normally carries) on the bike, measure the chain slack along its bottom run, at roughly the halfway point along the swingarm.
* Typically the chain slack at the tightest point should be somewhere between 3/4 and 1 inch with the bike on the ground and weighted; it should be around 13/4 inches with the bike on a stand and no weight on it. The owner's manual will provide the exact specs.
* Adjust the chain to the correct specs following the procedure outlined in your owner's manual.

The Wrap-Up
Overall the procedures outlined here should take maybe an hour to complete. If you do them twice a year and lubricate the chain on a regular basis in between, you'll save at least double that time simply because you won't be adjusting the chain every 600 miles. Further, a well-maintained set of chain and sprockets will last upward of 30,000 miles or more, while you'll be lucky to see even 10K if you neglect them. As always, a little maintenance goes a long way.

Gear Me Up, Gear Me Down
No discussion of chains and sprockets would be complete without at least a passing reference to gearing changes. In the past some bikes sent to the American market would carry lower final-drive gearing than their European counterparts. This was because we placed a premium on acceleration and weren't particularly mindful of things like fuel economy or engine life, and in part this is still true with some bikes. Conversely, some manufacturers installed slightly taller gearing on their bikes than was optimum. This made for a more relaxed cruising pace, prevented overrevving and in some instances helped the bike get through noise and emission testing a little easier than it might otherwise.

Nowadays most manufacturers get the gearing right on, but under some circumstances a slight change in the ratio may prove helpful. Adding teeth to the countershaft sprocket or removing them from the rear sprocket will raise the gearing. The bike won't accelerate as hard, but engine rpm will be lower for a given speed and the bike will have more top end. Be careful here; raise the gearing too high and you may lose too much acceleration and passing power. There's always a chance, too, that the engine won't produce enough torque at high rpm to pull the new gearing, so in some instances top end will actually be reduced. I'd recommend no more than a one-tooth change at the countershaft or two teeth at the rear sprocket as a starting point.

If the bike lacks low- or midrange grunt, reducing the size of the countershaft sprocket or adding teeth to the rear end should fix the situation. Again, one tooth at the countershaft or two at the rear is the way to start; otherwise you may find yourself with a bike that pulls like a mule climbing a ladder off the bottom but runs out of breath at 75 mph.

Why So Slack?
In theory a chain should have zero play yet not be under tension. This ideal state is impossible to achieve for two reasons. First, sprockets are never perfectly round. There are always high and low spots in them that cause some portions of the chain to become tighter than others. Second, because a motorcycle's swingarm pivot and its countershaft sprocket aren't concentric, the chain gets tighter every time the swingarm moves. For those two reasons some chain slack is required. If it's not there, the chain, the sprockets and quite possibly the countershaft bearings will have a depressingly short lifespan.