Chains are vital links to the enjoyment of dirt riding. Although the method of transferring power from the engine to the rear wheel hasn't changed much in the last 50 or so years since motorcycle riders began taking their bikes into the dirt, the implements themselves have vastly improved, thanks to better technology and materials.
As Dave Chase of Pro Circuit says, "Luckily, chains aren't like they used to be 30 years ago." Amen! Broken chains used to be a common cause of DNFs in races. Not so today. Chains remain the most efficient method of linking engine to wheel. But unlike in the early days, premium-quality chains nowadays are shining examples of durability. There are lightweight versions for motocross and O-ring models that last eons through the most hideous off-road conditions imaginable.
Still, you can't simply set and forget. Despite the advances in materials and technology behind them, chains do require a bit of maintenance now and then in order to function optimally and for as long as possible.
Thus, we asked Chase to demonstrate just how he and the pros at Pro Circuit perform routine chain maintenance on the fleet of race bikes that flood their shop. It doesn't take much in the way of time or product, so anyone can do it. Just follow these easy steps.
(wire brush)After a race or ride, chances are your bike's chain is going to be dirty. Just how dirty depends on the conditions, of course. A sloppy mud race will foul the chain with significantly more debris than a supercross main event with its perfectly groomed surface. So the first step is to clean the bike, taking care not to direct jets of water from a pressure washer at the chain as that could force water into the chain's internals, displacing lubricant. Instead, after washing the bike, use a wire brush to remove caked-on dirt, grease or rust. If you're running an O-ring chain, skip this step as you'll damage the O-rings, which will degrade their protective capability. If you feel you must clean your O-ring chain, simply wipe it off with a rag and know that you're merely cleaning it for aesthetic reasons.
(finger)Make sure the chain is adjusted correctly-meaning, consult the owner's manual since the proper chain slack for a KTM is different than for a Honda. Don't depend on any manufacturer's marks on the swingarm when moving the rear axle to adjust chain tension. You can look down the chain from the rear of the bike and see if the rollers and links run exactly straight back from the countershaft to the rear sprocket. If an adjustment is necessary, use a steel tape measure to double-check the distance from, say, the swingarm pivot to the rear axle, and measure both sides. If it's not equidistant on both sides, you'll find accelerated wear of both the chain and sprockets. Wear on the inner and/or outer edges of the sprocket teeth indicates the sprockets are not aligned. Here, Chase demonstrates a quick way to check for proper chain slack on this CRF450R; be aware that the three-finger method may be incorrect for other bikes.
Take a close look at the master link. The master link clip is basically a thin, U-shaped piece of metal, and the closed end must point in the direction of chain travel. If the open end is the leading end, chances are it'll catch on something and pop off-with the master link following suit shortly thereafter. Muddy conditions can grind the clip down and render it unreliable, so replace one that's worn down too far. Make sure it's not bent, too.
Lubricate the chain. Chase advises spraying the inside of the chain near the countershaft sprocket while spinning the rear wheel. This helps minimize lubricant flinging off. If you have an O-ring chain, use a light-viscosity lube to prevent surface rust and keep the rubber O-rings pliable. The reason for this is that O-ring chains are prelubricated and those O-rings help keep lube in and debris-and external lube-out. Do not use penetrating-oil-type lubes, including WD-40. These sprays contain solvents that can damage the O-rings or even wash away the factory grease.
If you find that the sprocket's teeth are excessively worn-especially if they're hook-shaped or exhibit high wear on the inner and/or outer sides-chances are the chain needs to be replaced. And if you replace the chain, you should also replace both sprockets at the same time. These three items wear as a set, which shouldn't be a surprise if you think about it.