Motorcycle technology is almost a Darwinian process. As motorcycles of all kinds climb the evolutionary ladder, they drop the features that once helped them survive, but are now outdated baggage. The ignition points are all but gone, air-cool motorcycle engines are on their way out, and fuel-injection appears ready to make carberators obsolete. Shafts and belts dominate the final-drive thanks mainly to the very popular and growing touring and cruiser markets, due to the low maintenance, high reliability, and clean, quiet operation are all primary survival traits.
You might think drive chains were next on the obsolete technology list, but don't count them out just yet. Chains not only still spin rear tires to life, they offer advantages that shaft-drive and belt-drive don't, such as efficient power transmission, and the ability to change gearing quickly and easily. And with a little maintenance and care, they can match shafts and belts for reliability and quiet running.
0-ring chains, once considered rare and to expensive, are now the chain of choice on most all chain-drive motorcycles. It was the switch to O-ring technology that almost single-handedly gave chains a reprieve from the bone-heap of motorcycle technology. Non-O-ring chains had to be lubricated often and excessively, and rewarded such care by flinging the lube all over the motorcycle, the rider and whatever else was within ten feet. Even the most carefully oiled chains produced noice and stretched, and the clip-type master links were the chains weakest link. There was little to like about motorcycle chains until someone got the idea to seal the lubricant inside the chain instead of spraying it on the outside and hoping it went where it was needed.
This isn't to say O-ring chains never need lubed. Even though the parts of the chain under the most stress-the pin and bushing-are constantly lubricated, you still need to apply some lube to the rollers, those parts of the chain that contact the sprocket teeth. You need to lube not only the outside of the rollers, which leaves some of the lube to the sprocket teeth, but see to it that lube penetrates the inside diameter of the roller, where it contacts the outside of the bushing--this is the part of the chain that is not sealed, and the lube runs out in time. You should also apply a very thin layer of good quality chain lube to the side plates, to prevent corrosion, and to the outside of the O-rings themselves, which you can see between the sideplates, to keep them from drying out and cracking.
The film of lubrication that keeps a motorcycle O-ring chain clean and reliable also collects dirt and grime. Regular cleaning should be a part of your motorcycle chain-maintenance routine. Chain manufacturers most often recommend using a solvent like kerosene (never gasoline or any other highly flammable solvent) and a worn toothbrush with soft bristles. Don't scrub too hard on the O-rings or you'll break them. While you're at it, clean the sprocket teeth. The rear sprocket will obviously be easier to get at, but it's worthwhile to take off the countershaft sprocket cover now and then and clean out the accumulated muck that builds up underneath. Also clean off any plastic guides or runners that the chain slides over or near.
As good as they are, even the best motorcycle O-ring chains wear out. The most obvious clue is when you've used up all of the available adjustment as indicated by the chain-wear marks on your motorcycle swing-arm. Chain manufacturers have various wear standards, some based on the percentage of elongation compared to a new chain, others on the distance you can pull a link off the back of the rear sprocket. Both of these methods are indicative not of stretching, as many riders believe--the metal in a chain does not stretch--but of an accumulation of clearance in the friction surfaces of the chain itself. The more miles on a chain, the more wear on the rollers, bushings and pins, and the more clearance there is between them.
Sprockets wear out, too, and when they do, your motorcycle chain won't be far behind them. Sprocket teeth should be symmetrical, not hooked as you'll see on extremely worn sprockets. Worn or hooked teeth put extra strain on the chain rollers. If one of the sprockets on your bike looks that way, replace it and the chain, since the damaged teeth may well have damaged the rollers. Like the parts in a new engine, a new chain and sprockets "bed in" to each other as the miles go by. If you replace one and not the other, the mismatch between the new and old parts accelerates the wear of both. Think of the chain and sprockets as a single component, rather than three separate ones, and you'll get the most miles for your money.
Replacing a chain and sprockets is a job that isn't beyond the skills of the average backyard motorcycle wrench. Like any job, though, there are fine points that you don't want to skip. First, make sure the replacement chain you buy is the right one for your bike. Follow the chain manufacturer's recommendation with respect to the chain's size and tensile strength, and find out if you need a special tool to install the master link. Don't forget to buy new lock tabs for both sprockets, because you'll want to replace the old ones even if they're only slightly bent--this is no time to pinch pennies.
While the rear wheel is off the bike, check the rear hub dampers, if any, and replace them if they're worn. Next, stick your finger in the wheel bearings and spin them slowly, feeling for any notchiness or lateral movement of the inner race. Check the wheel bearing seals for leaks, cracks or tears, and replace them if you see anything that makes you as much as wonder if you ought to. And have a new cotter pin handy for the rear axle nut when you put everything back together.
Adjust your motorcycle chain, old or new, to the motorcycle manufacturer's specifications. As a rule, too loose is better than too tight, which puts a strain not only on the chain but on the transmission countershaft and rear wheel bearings. Too loose can be overdone, too, such as when the chain begins taking bites out of the swingarm or the chain guard. Check the adjustment 50 miles after installing a new chain, and again at 250 miles, and then go back to the recommended intervals. If you ride hard, or carry heavy loads, or ride where it's dusty or wet, check the chain--and lube and clean it--more often.
Every time you clean the chain take a close look at the O-rings. The integrity of the O-rings is essential to chain life. If you spot any O-rings that are broken or missing, replace the whole chain. Kinks in the chain can be caused by dirt build-up or ordinary wear, but are more often the result of sprockets that are out of alignment, either out of parallel with each other, or parallel but not in line. If the sprockets are aligned, and cleaning the chain doesn't take the kinks out, replace the chain.
Even though in terms of motorcycle technology chains are practically as old as the dinosaurs, they're not ready to be shuffled off to the Jurassic parking lot just yet. Like those ancient bad boys, they're simple, tough and efficient, ideal qualities for a survivor. And while chains might not survive as long as the dinos did, they'll probably still be around after the rest of us are riding in Heaven! |