Maintenance 101

Even routine DIY motorcycle maintenance, especially when it involves a new one, often gets done in the fog of a mild anxiety attack. Or, while there’s a warranty involved, it gets done by someone else. That’s largely because there’s so much to know these days, so many dire warnings in the manuals and so few assurances that it’s done right, or done enough. If “the book says” you check the oil when the engine’s cold… what’s cold enough? If that oil is to be changed with the engine warm… exactly how warm should it be? Trying to perform the tasks involved, once you understand the need, makes for a better relationship with the bike and improves your self-confidence too. But, knowing why your bike’s manual tells you to perform certain tasks and how to interpret what they really mean may help make sense of them. The first big hint is that there are no universal answers to these kinds of questions, or the thousands of others that come up during maintenance chores of all sorts.

For instance, owner manuals recommend oil changes at intervals, which only roughly reflect your engine’s actual requirements. Sure, oil must be periodically changed because it becomes contaminated and it wears out. But, precisely how often that might need doing, in reality, can only be determined by you, as your machine is ridden your way, in your environment. Another of my pet peeves with recommended intervals stems from the fact that when I say contaminated, I do not mean by all the carbon particles that blacken used motor oil. These are benign as long as they don’t clump together to clog oilways and the detergent/dispersant additives in good-quality motor oils (as I’ve asserted here in the past) keep that from happening. The contaminants that do damage are silica (silicon oxide) and acids. The additives in oil are there to sacrifice themselves, to prevent scuffing and metal-to-metal contact on moving parts, for the sake of the engine. But let’s not forget that oil, whether old-fashioned refined stuff or synthetic, wears out as well. It’s made up of long-chain molecules that get sheared into shorter chains in a running engine. This means it loses viscosity (as well as additives) with time in service. So—fresh oil is a fresh start!

Engines pump about 10,000 gallons of air for every gallon of fuel consumed, and takes in with that air plenty of grit. A good air filter stops everything bigger than a micron in diameter, and anything smaller mostly just floats around in the 0.001-inch minimum thickness oil films separating moving parts in the engine. But there are places, and times, when sub-micron particles do get into the act. Each time you drain your bike’s oil the fine grit leaves with it.

Oil filters are a second line of defense for any micron-plus grit that gets past the air filter, and they also trap oxidized oil clots and the flakes of metal that seem to always pop off heavily loaded internal parts. (You almost always find metallic particles in an engine’s crankcase, meaning that the oil stayed thick enough to hold such detritus even when hot.) So, if it’s convenient (or fun) to go for a long ride before an oil change, do it! But, if time pressures mean you can only run the engine a couple minutes to stir up the oil before pulling that drain plug, then do that. The only real difference is that cold oil takes longer to drain.

You’ll be draining more than grit with that oil. You also get rid of acids formed during combustion, which are severely corrosive. These acids collect in the mufflers until exhaust heat raises their temperature above the dew point of the acids. Same thing happens inside the engine, where the upper cylinder walls are exposed to acid etching during the early warm-up period. And it is this etching (far more than abrasion) that causes cylinder wear.

Careful; concerned owners who take the time to warm an engine thoroughly before riding actually cause more acid damage. Impatient types, who ride away immediately, get a faster warm up and the least acid damage to engine and exhaust! Of course, if they hammer that cold engine, they’ll beat up pistons and blow gaskets and other bad things, but if they show restraint until the engine is up to operating temperature—no harm done.

Give thought to the oil in your forks too. It oxidizes, depletes its additives and needs periodic replacement, the difference being… again… that this can occur at mileages (and under usages) that vary hugely from what is recommended in the manual. When the time comes, consider whether the viscosity of the fork oil is right for you… and never use anything but fork oil!

All late-model Harleys require DOT4 brake fluid. After decades of DOT5 this seems retrograde to me, but I’m not the European engineer at Brembo who decided that was the thing to do for H-D, once the option of ABS brakes was on the table. Read the label on your master cylinder lid and if indeed you need DOT4, be diligent about regular replacement—because the stuff is hygroscopic (attracts water like a speeder attracts cops) and once there’s water in there, it lowers the fluid’s boiling point and causes corrosion (in a system that’s not rebuildable). ABS or not—once that happens—all bets are off.

Same story with batteries. The greatest killer of batteries is winter storage and/or long-term disuse. During these periods of inactivity the battery attacks itself! White lead sulfates fog the plates, leaving it unable to deliver any useful power or to take a charge. Conscientious use of so-called “smart” automatic chargers is the best remedy, since they won’t over-charge and kick in whenever the battery calls for help.

Fuel (I refuse to call it gasoline anymore) is a PIA these days, on several levels. The ethanol content in almost all populated areas in most states these days is just plain deplorable. It eats rubber, corrodes most everything else and makes the fuel deteriorate into varnish much too quickly. Used to be that the best thing to do for winter storage or long-term lay-ups was to drain the stuff. Now, that’s not so straightforward of an option with EFI components. Chemical additives (like Sta-Bil or Harley’s own “winter” additive) that retard or reduce the disintegration of the compounds in fuel (as we know it) might be as good an answer as any—short of fresh fuel on a regular basis.

Spark plugs are so easy to change on Harleys, I’m surprised people don’t do it more often. Same with plug wires. Age affects wires as much or more than mileage, but both items can quit or act up when you least expect it. Upgrades to Screamin’ Eagle (or good aftermarket) plugs and wires are a bonus when the time comes and it actually comes (for stock stuff) about every second or third time you change fluids.

Basically, whether you do it (which is perfectly feasible and gets easier every time), have a knowledgeable friend teach you, or pay a professional—these maintenance chores (and many others I’ve not mentioned) are important. You simply cannot ignore them like most of us ignore our cars. Any investment and/or involvement in taking care of your machine when you park it in bad times will be paid back many times over in how you roll with the good times.