Ironhead Sportster Maintenance
Article by Mark Trotta
Repairs and maintenance are part of motorcycle ownership. I've owned and worked on many Ironheads, and although they do require more attention than other makes and models, the worst part is always fixing something previously done incorrectly.
Change Engine Oil
For newer Ironhead owners, it's important to know that there are two separate oil systems. And there are plenty of stories how a well-intentioned DIYer drained one and filled up the other.
The engine oil is in the tank right under the seat. There is a drain plug on the bottom.
Then there is separate oil in the primary and transmission. This gets drained with the plug on the bottom of the (left side) primary cover.
NOTE: There is also an oil plug on the bottom of the engine, but it is not needed to drain engine oil (unless the motor is sumped).
Most classic bikes are air-cooled, and automotive oils do not meet the required specifications for air-cooled engines. This results in higher operating temperatures and reduced engine life. Unless it's an emergency (like being stuck on the side of the road), use the proper-specified oil.
Presently, I'm using Maxima V-Twin mineral oil in my old Harleys. It's also offered in synthetic.
On Iron Sportsters, engine oil and primary oil are the same.
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Valve Adjustment
Every year and model Ironhead has solid lifters. Adjusting valves on a late 50's or early 60's bike is the same as on 70's and 80's bikes.
Read: How To Adjust Ironhead Valves
The factory service manual states that valve adjustment should be done after 500 miles of initial engine break-in, then at 1,000 miles, and every 2,000 miles thereafter.
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Rear Chain Maintenance
Do not over-tighten rear chain! There needs to be play in it, about an inch up or down is common. When it's too tight it will wear out sprockets, as well as add stress to the transmission bearings.
There's two big reasons why you should regularly lube the drive chain. The first is, lack of lubrication leads to premature chain and sprocket wear, And more importantly, to lessen the chance of a chain snapping while under acceleration.
A bike chain is comprised of outer links, inner links, rollers, and pins. When your chain is lubed correctly, it allows all these parts to move freely.
Most modern motorcycle chains are sealed with O-rings, which is a good upgrade for a street-driven Ironhead. But they still need periodic lubrication. Most riders agree that a well-maintained chain means doing less chain adjustments.
Best Chain Lube
Anything is better than nothing, and I've heard of all sorts of products being used, from WD-40 to chainsaw oil to 80W90 gear oil. Presently, I'm using an aerosol chain wax.
TIP: After applying chain lube, wipe off all excess with a rag, otherwise it will sling onto places you don't want it to be (like your pants).
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Motorcycle Battery Care
Just how good is your battery? Since kickstart bikes don't use a battery for starting, it can be in pretty bad shape without you knowing. Check the connections, and the fluid level. Top off with water if necessary, and allow to stand awhile before charging. Put a small trickle charger on it overnight.
Constant-Current Battery Chargers
Constant-current chargers are often called smart-chargers, because they can vary the charging voltage to keep current constant. The phrase 'battery tender' is a brand name, and they are one of the more popular battery maintenance devices.
Shop: Trickle Charge Battery Tender
These chargers generally put out one-amp or less. Never use an automotive battery charger on a motorcycle--the higher amperage will warp the plates inside the battery.
Recharging a Dead Battery
Because motorcycles are sometimes recreational vehicles, they often sit for a long time between use. A battery can only be deep-cycled a limited number of times.
Some of the newer technology battery chargers claim to be able to restore a deeply-discharged maintenance-free battery. This is done by increasing the initial charging voltage to overcome the internal resistance.
Do I Need To Use Distilled Water In My Battery?
Adding distilled water to a battery is recommended simply because it has no impurities in it. If you live in an area where your water supply has a very high mineral content, use distilled water in your battery. If not, the choice is yours. It certainly does no harm, but is not always needed.
Battery Charger Pigtail
Installing a little pigtail to the two terminals vastly reduces the chances of the positive wire touching the chassis. This could explode the battery before the wire melts.
Safety Tip: Do not pull off charging cables before unplugging the charger. This reduces the chance of getting a spark at the terminal. And wear safety glasses.
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Carb, Fuel, and Air
Sitting unused, gasoline turns bad, and over several years of time it will turn to varnish. Fuel system maintenance includes checking fuel lines for cracking and weathering, and checking your fuel filter to make sure it's not clogged.
Read: Motorcycle Carb Problems
Read: Best Carb For Ironhead
Install a quality fuel filter, such as this glass bowl gas filter from Milwaukee Twins.
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Factory Service Manual
Knowledge is the best tool you can have, and having a factory shop manual that covers your year and model is invaluable. You'll end up referring to it over and over again.
Chilton and Haynes manuals are OK for minor stuff, but they are nowhere near as complete as a factory shop manual.
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Tire Maintenance
Before riding, visually inspect tires all the way around for any signs of damage.
Check tire wear and tire pressure. Maintain correct inflation pressure for your year and model.
To clean sidewalls, use a mild soap solution and rinse off with plain water. Never use protectants, cleaners or dressings. They will degrade the rubber.
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Front Fork Maintenance
It is recommended that fork oil be changed every other riding season, or every several years, depending on how much riding is done. Most manufacturers recommend 20 weight fork oil for average conditions. For extreme conditions, use 10 weight (cold weather) or 30 weight (warm weather).
Dry fork requires .5 to 1.0oz more than the wet amount due to residual oil left clinging inside the fork.
WET: Means you just drained the oil out of the plug and want to refill it.
DRY: Means you disassembled the forks and cleaned them dry inside and out.
Another way to measure is to push the forks down all the way while the caps are off, and fill it to 5" below the upper edge of the fork tubes.
Replace Fork Seals
Replacing leaking front fork seals can be a tedious project, but it is do-able.
Read: Replace Sportster Fork Seals
This is a good time do other related work, like polishing the lower forks or adding gators.
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Cables
Other Iron Sportster maintenance includes adjust and lube throttle cable, adjust and lube clutch cable, and adjust and lube brake cables.
Read: Ironhead Clutch (1971-1984)
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Sportster Brake Articles:
Rebuild 1973 through 1977 Front Caliper
Rebuild Harley Dual Disc Calipers
Rebuild Harley Master Cylinder
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