priebe Posted September 21, 2022 Share Posted September 21, 2022 Apologies if this has already been discussed, feel free to direct me to the threads. I have around 10k miles on my 2019 900 GT and was thinking about replacing the spark plugs ahead of my upcoming 1,000 mile trip. The owners manual states to replace the spark plugs every 8k miles. Looking at the specs for the recommended NGK 2308 CPR9EA-9 Nickel Spark Plug directly on the NGK website (link below), it states the "longevity" on this particular plug is 30k miles. My two questions are 1) why only 8k miles recommended by Yamaha? 2) what are folks seeing for real-life longevity out of these plugs and is there even any noticeable difference with a new set of sparkys? https://www.ngk.com/ngk-2308-cpr9ea-9-nickel-spark-plug Link to comment Share on other sites More sharing options...
HGP61 Posted September 21, 2022 Share Posted September 21, 2022 I've 20,000 miles on my original set and wasn't planning to change them until I have the bike stripped down for a valve check hopefully sometime soon. Don't think they need to be changed at 8,000 miles 2 Link to comment Share on other sites More sharing options...
johnmark101 Posted September 21, 2022 Share Posted September 21, 2022 Did not change mine until I performed the first valve inspection at 20,000 miles. At that time the original plugs still looked to be in good condition. 1 There is nothing like spending a day riding with friends in the grip of a shared obsession. Link to comment Share on other sites More sharing options...
Supporting Member texscottyd Posted September 21, 2022 Supporting Member Share Posted September 21, 2022 39 minutes ago, johnmark101 said: Did not change mine until I performed the first valve inspection at 20,000 miles. At that time the original plugs still looked to be in good condition. Good to hear, since I’ve also been waiting to do plugs at the 24k major service. I’ll be taking it in very soon, and will see how the plugs looks (and how far off the valves are) Link to comment Share on other sites More sharing options...
KrustyKush Posted September 21, 2022 Share Posted September 21, 2022 I changed mine a couple weeks ago at just past 12k mikes. They looked fine and surely could have gone much longer. I read somewhere the reason the factory wants them replaced so often has to do with some sort of dissimilar metals reaction in the threads. The Harley big twins get plugs changed every 30k miles. They cost $5 each. 1 Link to comment Share on other sites More sharing options...
Supporting Member betoney Posted September 22, 2022 Supporting Member Share Posted September 22, 2022 Mine are also changed when the valves get checked, around every 22,000 miles. ***2015 Candy Red FJ-09*** Link to comment Share on other sites More sharing options...
Supporting Member dazzler24 Posted September 22, 2022 Supporting Member Share Posted September 22, 2022 2 hours ago, KrustyKush said: I changed mine a couple weeks ago at just past 12k mikes. They looked fine and surely could have gone much longer. Ditto for me. My old ones could easily have stayed in for another 12K miles by the looks of them. Link to comment Share on other sites More sharing options...
PhotoAl Posted September 22, 2022 Share Posted September 22, 2022 Same here, changed them at I think 10 or 11K and then again at 19,000 when I did the valve clearances just because I was in there. From what I see they are good for at least 12,000 and probably more. Not sure why Yamaha has the replacement at 8,000 miles. I've done two 6,500 mile trips and that is almost a spark plug change interval. I've talked about it before, think the recommended intervals on a lot of stuff are more for the original FJ and a bike that has lots of shorter fun trips with lots of up and down thru the gearbox. Link to comment Share on other sites More sharing options...
Pupsi Posted September 22, 2022 Share Posted September 22, 2022 My manual says to CHECK at 6k miles and replace every 12k miles 1 Link to comment Share on other sites More sharing options...
Supporting Member texscottyd Posted September 22, 2022 Supporting Member Share Posted September 22, 2022 12 minutes ago, Pupsi said: My manual says to CHECK at 6k miles and replace every 12k miles Well, the bike was running at 6K miles, so I can confirm that I checked: Yes, it still had spark plugs at that time. 😳 Apparently I never read the service schedule in enough detail, and somehow thought that the 24k valve check/adjust interval was aligned with the spark plug replacement. It will be interesting to see how they look… the bike runs great at 23.5K miles, so I’m guessing they’re going to look fine. Link to comment Share on other sites More sharing options...
Supporting Member betoney Posted September 22, 2022 Supporting Member Share Posted September 22, 2022 54 minutes ago, texscottyd said: the bike runs great at 23.5K miles, so I’m guessing they’re going to look fine. At 72K miles, mine have been changed 3 times, the plugs looked/performed fine each time they were changed. On previous bikes my interval was @ 25K w/ no issues. 1 ***2015 Candy Red FJ-09*** Link to comment Share on other sites More sharing options...
Premium Member 2and3cylinders Posted September 22, 2022 Premium Member Share Posted September 22, 2022 2 hours ago, texscottyd said: Well, the bike was running at 6K miles, so I can confirm that I checked: Yes, it still had spark plugs at that time. 😳 Apparently I never read the service schedule in enough detail, and somehow thought that the 24k valve check/adjust interval was aligned with the spark plug replacement. It will be interesting to see how they look… the bike runs great at 23.5K miles, so I’m guessing they’re going to look fine. As I'm sure you've read, waiting until 24000 miles to check the valves is not recommended given the propensity of our engines to have tight valves much sooner... Link to comment Share on other sites More sharing options...
Supporting Member texscottyd Posted September 22, 2022 Supporting Member Share Posted September 22, 2022 2 hours ago, 2and3cylinders said: As I'm sure you've read, waiting until 24000 miles to check the valves is not recommended given the propensity of our engines to have tight valves much sooner... It wasn't exactly the plan, but here we are... I'll get it in at about 23,975 miles based on the current projection. I have the new Speed Twin to ride while it's down, so at least I won't miss any fall weather riding opportunities. 1 Link to comment Share on other sites More sharing options...
Premium Member 2and3cylinders Posted September 22, 2022 Premium Member Share Posted September 22, 2022 1 hour ago, texscottyd said: It wasn't exactly the plan, but here we are... I'll get it in at about 23,975 miles based on the current projection. I have the new Speed Twin to ride while it's down, so at least I won't miss any fall weather riding opportunities. Dam you! Did you have to bring up your ST!!! (FYI, I just did my best imitation of Homer drooling...) 1 Link to comment Share on other sites More sharing options...
Supporting Member texscottyd Posted September 22, 2022 Supporting Member Share Posted September 22, 2022 2 hours ago, 2and3cylinders said: Dam you! Did you have to bring up your ST!!! (FYI, I just did my best imitation of Homer drooling...) Hey Bret, did I mention that I have a new Speed Twin? ‘Cause, you know… I have a new Speed Twin. 😀😀 1 Link to comment Share on other sites More sharing options...
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