As the title says, just wondering how long plugs normally last in a ST 1100 ?
How many miles are you getting out of Sparkplugs
- Thread starter St-Gerard
- Start date
I put in a set of Iridiums so long ago I can't remember, but I don't put that many miles on my bike each year these days.
I got around 30,000 miles on the last set of iridium plugs I put in.
Edit: I checked my notes and it was 42,000 miles.
Edit: I checked my notes and it was 42,000 miles.
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Andrew Shadow
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I don't know what the current landscape is but as an indication spark plugs used to be covered by an 80,000 KM / 50,000 mile warranty legislated by emissions regulations. This was for standard plugs long before iridium plugs were a thing and when engines still had carburetors. I can't imagine that much cleaner burning fuel injected engines has reduced that threshold.
Many fuel injected engines recommend that the first spark plug replacement be done at 160,000 KM / 100,000 miles. There is no reason that they need to be replaced sooner solely because they are in a motorcycle engine.
I changed my standard plugs on my ST1300 at around 100,000 KM / 60,000 miles and doing so made no difference in driveability or fuel efficiency. I changed them only because I had already bought them. If I had not I would not have.
The short replacement interval suggested by Honda for motorcycles is ridiculous. Spark plugs do not last for ever and require regular replacement but, devoid of a problem that causes a spark plug to foul, many people change their spark plugs to often.
Many fuel injected engines recommend that the first spark plug replacement be done at 160,000 KM / 100,000 miles. There is no reason that they need to be replaced sooner solely because they are in a motorcycle engine.
I changed my standard plugs on my ST1300 at around 100,000 KM / 60,000 miles and doing so made no difference in driveability or fuel efficiency. I changed them only because I had already bought them. If I had not I would not have.
The short replacement interval suggested by Honda for motorcycles is ridiculous. Spark plugs do not last for ever and require regular replacement but, devoid of a problem that causes a spark plug to foul, many people change their spark plugs to often.
Maybe I'll put a new set in this year. My iridiums are at 70k with the bike running just fine and gas mileage unchanged.
Lower 40s around town and higher 40s on a trip.
Did we loose the thread that explains how to tell the fakes from the real thing?
Lower 40s around town and higher 40s on a trip.
Did we loose the thread that explains how to tell the fakes from the real thing?
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ST1100Y
Site Supporter
Well, according to the service schedule 12,000km/7500miles...
Bear in mind that this was for "regular" plugs and is also intended as precautionary recommendation to prevent sudden engine failure due to a failing plug*...
IMO should iridium plugs give at least twice that lifetime...
(the ones in my trusty '96 Toyota are even rated to last 120,000km/75,000miles... but such counts for the electrode burning off, not other mechanical fault/damage...)
*BTDT, a crack in the ceramic insulator shunted the #4 plug on my '92 ST1100 once -> no spark on left bank -> no start...
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I noticed when I changed them, the plugs didn’t look that bad, but I found the bike much more responsive and seemed to have gained more power. It was the only item I messed with, so can only attribute the “surge” in power to the spark plug change.
I do agree that Honda's recommended spark plug replacement interval was (is) very conservative there are significant differences in motorcycle and automobile applications that reduce the service life of motorcycle spark plugs. Keeping it topical to the ST1100 and comparing to a similar small displacement 4 cylinder automobile engine the motorcycle uses only two ignition coils so the plugs fire twice per revolution compared to a 1999 Honda Civic which has 4 individual coils, one for each plug firing once per revolution. The ST's ignition system is a wasted spark design firing two plugs at the same time to save weight and component complexity. The spark plug fires on both the compression and exhaust stroke. The car engine has a lower redline and is geared to turn at fewer revs at the same highway speed (about 15% less) as the ST so over the life of the spark plugs the motorcycle plugs fire more than twice as often as the automobile plugs do. This is reflected in the Honda service recommendations - Civic 30,000 miles and the ST 16,000 miles.
With my 2005 ST1300 I followed the 16,000 mile recommendation for at least the first 100,000 miles (I no longer have the service records) but at some point in the next 80,000 stretched the interval to 24,000 and later towards 30,000 miles.
I replaced the plugs in our 1991 right after we bought it....11 years ago now. Replaced them just this past week while troubleshooting. Plugs were not the problem.
OP
OP
Will be inspecting plugs soon, probably have 30,000 kilometers on the ones in the motor. Still have a Slight but annoying Vibration between 2500 and 3000 rpm , in any gear. Above 3 grand smooth, nothing on the handle bar.
Andrew Shadow
Site Supporter
I do not disagree with anything that you wrote. I do appreciate the differences in operating conditions between motorcycle and automobile engines. I am not advocating for a 60,000 mile change interval or one that is on par with automobile maintenance schedules. I am just stating that in my opinion Honda's recommended change interval is ridiculously low and that spark plugs are often changed much to prematurely with no real benefit. This is similar to the old convention of changing the engine oil every 3,000 miles as was the norm when engines were carbureted and ran much dirtier than they do now. Oil change intervals are much longer now because of both better oils and much cleaner burning engines due to computer controlled fuel injection. The oil does not become contaminated any where near as quickly as it does with a carbureted engine. In this case even Honda calls for 8,000 mile oil change intervals but many people continue to adhere to 3,000 mile change intervals based on old maintenance standards.
- Copper/Nickel: Typically need replacement every 20,000 to 30,000 miles.
- Platinum & Iridium: More durable, lasting 60,000 to 150,000 miles or more, with iridium often at the higher end.