Motorcycle Safety Series
Here in the Northeast, the weather still didn’t break, although one nice day allowed me to log about 200 miles before getting stuck in a massive, cold rain storm. But getting stuck in the rain is still better than not riding at all. And an unprepared bike during nature’s unexpected downpours can cause an accident, sometimes even a deadly one, if you have a major engine malfunction, so let’s get into the third part of my bike preparation series, reading spark plugs.
Some riders only pull out one plug, but I like to check them all. So get those plugs out and compare them to the pictures posted at the bottom of the article (and remember this is the same for your car, so this information will be useful during your next car tuneup).
Here’s a breakdown of what this all means:
- Carbon Deposits: Dry sooty deposits are a good indication of a rich mixture or weak ignition. Possibly a clogged air filter, high float levels, a sticking choke or worn ignition points. Causes misfiring, hesitation and hard shifting.
- Oil Deposits: Oily coating means oil is leaking into the combustion chamber from worn valve guides or piston rings. Investigate this, make necessary repairs and use new plugs. Causes hard starting, misfiring and hesitation.
- Too Hot: Blistered, white insulator, eroded electrode and absence of deposits results in a short plug life. Check plug for heat range, the over-advanced ignition timing, a lean fuel mixture, sticking valves and intake manifold vacuum leaks. Also check the coolant level and flow.
- Preignition: Melted electrodes. White insulators may be dirty because of misfiring of flying debris in combustion chamber. Check heat range, over-advanced ignition timing, clogged cooling system, lack of lubrication and lean mixture. Causes engine damage.
- High Speed Glazing: A glazed, yellowish appearance on insulator, which indicates that the temperature in the combustion chamber has risen suddenly during hard acceleration. Normal deposits melt to form a conductive coating. Install new plugs, considering a colder plug if necessary. Causes misfires at high speeds.
- Gap Bridging: Heavy combustion deposits accumulate and bridge the electrode gap. The plug stops firing, resulting in a dead cylinder. Find the plug and remove the deposits or replace it.
- Normal: Brown to grayish/tan color and slight electrode wear. Correct heat range for engine and operating conditions. When installing new plugs, use the same heat range.
- Ash Deposits: Center and/or side electrodes will have light brown deposits, usually derived from oil and/or fuel additives. If excessive deposits accumulate in a short time or low mileage, install new valve guide seals to prevent seepage or oil into combustion chambers…also try a different brand of gas. Because excessive amounts may mask the spark, this causes misfires and hesitation during acceleration.
- Worn: Normal color with rounded electrodes and small amounts of deposits on the firing end. Replace with new plugs of the same heat range. Causes hard starting in damp and cold weather and poor fuel economy.
- Detonation: Cracked or chipped insulators (sometimes caused by improper gap settings). Use care when setting the gaps; avoid lugging the engine. May cause piston damage.
- Splashed Deposits: If your motor has been misfiring for a long period of time, deposits can loosen when normal combustion temperature is restored by an overdue tune up. At high speeds, deposits flake off the piston, thrown against the hot insulator, causing a misfire. Replace the plugs with new ones or clean the old ones.
- Mechanical Damage: Caused by a foreign object in the combustion chamber or the piston striking a plug that’s too long. If this happens, investigate and repair; if the plug’s too long, replace it with the correct one. This can cause a dead cylinder, resulting in piston damage.
Also, take a few seconds and check your sparkplug gap. Make sure it’s correct to your manufacture’s specifications. A gap too small equals a thin and weak spark, causing hard starting and high exhaust emission levels, resulting in increases fuel consumption. A gap too large and the ignition system will not be able to cope with the spark demands, causing misfiring.
That’s it for this week. Next week, we’ll wrap up this series with some additional tips that will make for a safer season of riding. Remember, motorcycles are an extension of who we really are, so keep yours tuned and running at optimal performance.
