Chain and Sprocket Maintenance

How To

In the world of new cruisers, chains and sprockets have just about disappeared, at least as far as final drives go, so you may question why I'm devoting this much ink toward their maintenance.

Simple. Despite the current popularity of belts and shafts there are quite a few older cruisers and standards running around with chain drives on them, and I'm willing to bet a cold six-pack against a warm glass of milk that at least 50 percent of you own one of them.

It's A Chain ReactionSince most of you have at least an understanding of how chains and sprockets transfer torque from the engine (or more properly the transmission) to the rear wheel, I'll forgo explaining the obvious parts of the process. However, it's worth noting that in many respects a chain is fundamentally a series of small bearings joined together in a long string, and like any other bearings they need to be kept clean, well lubricated and properly aligned if you expect them to do their job without complaining.

Maintain That ChainDirt is any chain's biggest enemy. When road grime makes its way into a chain it works like grinding compound to wear out the rollers and bushings. Some riders inadvertently aggravate the situation by overlubricating the chain. This allows the excess lube to form a sticky mess that acts as a dirt magnet, and wear is actually accelerated. Periodic cleaning prevents that from happening and also makes it easier to inspect the chain for wear and damage.

Chains should get a major cleaning at least once a year, more often if you're riding in dirty or dusty conditions. Ideally the chain should be removed from the bike, given a good soaking in solvent and a scrubbing with a bristle brush, then hung up to dry overnight before being lubed and reinstalled. That's a lot of work, especially if the chain has a riveted master link and if, like me, you're averse to performing hard labor when you could be out riding.

My preferred method is to slather the chain with a degreaser like Gunk, then give it a good scrubbing with a Grunge Brush chain-cleaning tool. I finish up by rinsing it down with the garden hose, then drying it with a clean rag. You can substitute WD-40, kerosene or any commercial chain-cleaning product for the Gunk and use an old paintbrush or nylon bristle brush instead of a gen-u-wine chain-cleaning tool, and the results will be just as good.

So why not just blow the thing off with a pressure washer or steam cleaner and be done with it? The answer is because it'll ruin a chain-especially an O-ring-type chain-before you can say "Holy smoke, parts-counter guy, that's an expensive replacement chain you've got there."

The high pressures and temperatures created by power washers and steam cleaners will wash the grease right out of a standard chain, which is bad enough, but at least you've got a fighting chance of getting it back in there. However, when those types of washers are used on an O-ring chain, the heat and pressure not only remove the lubricant but can also deform or damage the O-rings. Unfortunately even the best aerosol chain sprays won't be able to force the fresh lubricant past the O-rings (damaged or not), so what you'll be left with is a clean, albeit dry chain that's going to have a very short and unhappy life.

Normally I'd recommend relubricating the chain ASAP to drive out any residual moisture and protect it from the elements. But before you do, let's take five minutes to go over the basics. By the way, you can inspect the chain anytime you feel up to it; it's just a lot easier to do it when it's freshly cleaned.

Inspection = Detection
First give the chain the once-over. Make sure it's still relatively flexible by pivoting a few links. If the chain is really stiff or has a seized link you may be able to loosen it up with some chain lube, but in the long run you're probably better off replacing it right then and there. Acid damage from an improperly routed battery-vent tube is also a fairly common problem, and unfortunately anything significant will mean replacing the chain.

To inspect the chain for wear, grab it about halfway up the backside of the rear sprocket and give it a tug. If you can pull the chain more than halfway off the sprocket tooth, it's shot, and quite possibly so are the sprockets. I should mention that while this isn't the only way to check chain wear, it's the most reliable method when the chain is still attached to the bike.

Worn sprockets are usually pretty easy to spot-look for hooked, chipped or eroded teeth and, most obviously, missing ones. If any damage is found, replace both the sprockets and the chain. If the sprockets look good but the chain is worn, go ahead and install a new chain. Just don't expect it to last as long as the original, and on the next go-round be prepared to replace the chain and sprockets.

Next to dirt, improper chain/sprocket alignment is probably the most frequent cause of premature chain failure. Take a look at the chain and sprocket from the top. The chain should be centered on the sprocket tooth. If the chain runs to one side, the chain and sprocket are misaligned. This can usually be corrected with the chain adjusters, but in some cases you may have to align the wheels to get everything back on track. (See "Tips for the 411," Oct. '06). By the way, if the alignment appears radically off you may have other problems, so make sure the wheel spacers are in the correct position and the wheel and swingarm bearings are in good shape.

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.

The chain roller fits over the chain bushing to make up the roller link. The pin link holds adjoining roller links together to make up the chain. All those rolling and pivoting parts need a lot of care.
You can use commercially available chain cleaners or a stiff parts-cleaning brush to get the job done, but a specific chain-cleaning tool makes it a lot quicker.
If the link moves more than halfway off the sprocket tooth, the chain's worn out.
Physical damage is usually obvious. These rear-sprocket teeth are starting to show chips and wear, and the chain has cut down into the shoulders. These countershaft teeth are starting to hook-it's not terrible yet, but this sprocket is on the way south.
The chain rollers should be centered on the sprocket.
Get that lube right down in there, and let 'er fly.
This is about right for an unladen bike, while adding a Technical Editor's weight tightens things up considerably.