M8 problems
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,925
Likes: 8,027
From: poway
A couple points.
Always want to do back-to-back-to-back to see if the first test repeats with the stock plugs. To be fair, at a minimum, 3 pulls per test. Toss out the best and the worst of the 3. Use that as the comparator.
Also consider new plugs will always run the engine more efficiently than old plugs so these iridium plugs must be compared to new stock plugs to be fair.
I have never seen hp gains from super duper spark plugs or wires after many years of trials.
Bob
Always want to do back-to-back-to-back to see if the first test repeats with the stock plugs. To be fair, at a minimum, 3 pulls per test. Toss out the best and the worst of the 3. Use that as the comparator.
Also consider new plugs will always run the engine more efficiently than old plugs so these iridium plugs must be compared to new stock plugs to be fair.
I have never seen hp gains from super duper spark plugs or wires after many years of trials.
Bob
Cruiser
Joined: Apr 2017
Posts: 147
Likes: 23
From: Covington, La.
Today is the first time I've read this thread....and I am glad I did. I went to look at the '18's this past week-end and I must say they whetted my appetite for a new ride. I have a 2000 Electra Glide I bought from an elderly man with low mileage. Nice running bike but the new ones look so good and what the magazines say, they ride so well! Now I am conflicted. I went from trying to pick out a color to now standing back and saying, whoa, I didn't know they had these issues? I know my TC 88 has tensioner issues but that can be dealt with. With what I am reading about the new motor has me on hold. I did stop by the Honda shop today and the new GW looks really good and all the write ups rave about it. And it no longer looks like a geezer bike. I am big on reliability and next to that is accountablilty of the manufacturer to stand behind any and all issues that may arise with the product. I will test ride a new DCT GW this week and if the performance is anything close to what I read about it may be the next bike because as I said, reliability is number one concern for me....but I'm keeping the Glide because it is fun! 
Outstanding HDF Member
Joined: Nov 2008
Posts: 2,034
Likes: 128
Today is the first time I've read this thread....and I am glad I did. I went to look at the '18's this past week-end and I must say they whetted my appetite for a new ride. I have a 2000 Electra Glide I bought from an elderly man with low mileage. Nice running bike but the new ones look so good and what the magazines say, they ride so well! Now I am conflicted. I went from trying to pick out a color to now standing back and saying, whoa, I didn't know they had these issues? I know my TC 88 has tensioner issues but that can be dealt with. With what I am reading about the new motor has me on hold. I did stop by the Honda shop today and the new GW looks really good and all the write ups rave about it. And it no longer looks like a geezer bike. I am big on reliability and next to that is accountablilty of the manufacturer to stand behind any and all issues that may arise with the product. I will test ride a new DCT GW this week and if the performance is anything close to what I read about it may be the next bike because as I said, reliability is number one concern for me....but I'm keeping the Glide because it is fun!
PROBLEMS? MAN, WE AIN'T GOT NO STINKIN PROBLEMS.
Advanced
Joined: May 2007
Posts: 59
Likes: 6
From:
love my m-8
my 17 street glide has 21000 miles on it today. I changed the shocks out for progressive heavy duty air shocks. the adjustment of the stock shock all the way up to carry the 400lb load tweaks the swing arm enough that it wore the left side of the rear tire. looking at the tire, you can see the wear path has moved to the center, much better ride now and honestly, this was my only complaint about the new bike.
I change all three holes fluid at 3k intervals, I measure the fluids just to be sure I do not refill more than what came out! that way you never blow a seal. Happy to report, no issues like what is being reported. This month I will change the fork oil. My set up is a stock air cleaner, CVO street mufflers and a se race tuner which I loaded the stage one without modifications to the bike.
I change all three holes fluid at 3k intervals, I measure the fluids just to be sure I do not refill more than what came out! that way you never blow a seal. Happy to report, no issues like what is being reported. This month I will change the fork oil. My set up is a stock air cleaner, CVO street mufflers and a se race tuner which I loaded the stage one without modifications to the bike.
Stellar HDF Member
Joined: Mar 2016
Posts: 2,285
Likes: 965
From: Eastern NC
Today is the first time I've read this thread....and I am glad I did. I went to look at the '18's this past week-end and I must say they whetted my appetite for a new ride. I have a 2000 Electra Glide I bought from an elderly man with low mileage. Nice running bike but the new ones look so good and what the magazines say, they ride so well! Now I am conflicted. I went from trying to pick out a color to now standing back and saying, whoa, I didn't know they had these issues? I know my TC 88 has tensioner issues but that can be dealt with. With what I am reading about the new motor has me on hold. I did stop by the Honda shop today and the new GW looks really good and all the write ups rave about it. And it no longer looks like a geezer bike. I am big on reliability and next to that is accountablilty of the manufacturer to stand behind any and all issues that may arise with the product. I will test ride a new DCT GW this week and if the performance is anything close to what I read about it may be the next bike because as I said, reliability is number one concern for me....but I'm keeping the Glide because it is fun!
Seasoned HDF Member
Joined: Jul 2017
Posts: 5,749
Likes: 1,603
From: High Point, NC.
Today is the first time I've read this thread....and I am glad I did. I went to look at the '18's this past week-end and I must say they whetted my appetite for a new ride. I have a 2000 Electra Glide I bought from an elderly man with low mileage. Nice running bike but the new ones look so good and what the magazines say, they ride so well! Now I am conflicted. I went from trying to pick out a color to now standing back and saying, whoa, I didn't know they had these issues? I know my TC 88 has tensioner issues but that can be dealt with. With what I am reading about the new motor has me on hold. I did stop by the Honda shop today and the new GW looks really good and all the write ups rave about it. And it no longer looks like a geezer bike. I am big on reliability and next to that is accountablilty of the manufacturer to stand behind any and all issues that may arise with the product. I will test ride a new DCT GW this week and if the performance is anything close to what I read about it may be the next bike because as I said, reliability is number one concern for me....but I'm keeping the Glide because it is fun!
Yes you might get more bells and whistles with the GW, but its not a harley...lol JMO
Seasoned HDF Member
Joined: Nov 2016
Posts: 7,707
Likes: 13,985
From: Northern New Jersey
Today is the first time I've read this thread....and I am glad I did. I went to look at the '18's this past week-end and I must say they whetted my appetite for a new ride. I have a 2000 Electra Glide I bought from an elderly man with low mileage. Nice running bike but the new ones look so good and what the magazines say, they ride so well! Now I am conflicted. I went from trying to pick out a color to now standing back and saying, whoa, I didn't know they had these issues? I know my TC 88 has tensioner issues but that can be dealt with. With what I am reading about the new motor has me on hold. I did stop by the Honda shop today and the new GW looks really good and all the write ups rave about it. And it no longer looks like a geezer bike. I am big on reliability and next to that is accountablilty of the manufacturer to stand behind any and all issues that may arise with the product. I will test ride a new DCT GW this week and if the performance is anything close to what I read about it may be the next bike because as I said, reliability is number one concern for me....but I'm keeping the Glide because it is fun!
Stellar HDF Member
Joined: Sep 2009
Posts: 2,114
Likes: 666
While you are absolutely correct about a motor that is properly tuned, I suspect that some motors that are tuned to run lean might benefit from fancy plugs. After all HD did dual plug the M8s so it looks like they needed a little extra spark.. I'm amazed at how well they run even without a tune. Still, does a dual plugged M8 motor run better with the fancy plugs? My guess would be nope..
I believe Harley went to dual plugs to clean up the last bit of combustion for emissions compliance. Not sure if there is power to be had but simply doing a pull with the plug wires pulled from the outer plugs will answer that.
After many years of tuning these v-twins I have yet to see ANY increase from changing from a new HD plugs to any other aftermarket plug.
Also, until 2017, these engines used an ion-sensing anti-knock system that was based partly on sparkplug, wire, and coil resistance so changing to aftermarket stuff doesnt help the system and will tend to mis-report knock and as a result, timing being retarded up to 8-12degs depending on year/model for no good reason.
Bob
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Seasoned HDF Member
Joined: Dec 2005
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From: poway
When you are referring to motors that are tuned to run lean are you referring to Harley engines or engines in general?
I believe Harley went to dual plugs to clean up the last bit of combustion for emissions compliance. Not sure if there is power to be had but simply doing a pull with the plug wires pulled from the outer plugs will answer that.
After many years of tuning these v-twins I have yet to see ANY increase from changing from a new HD plugs to any other aftermarket plug.
Also, until 2017, these engines used an ion-sensing anti-knock system that was based partly on sparkplug, wire, and coil resistance so changing to aftermarket stuff doesnt help the system and will tend to mis-report knock and as a result, timing being retarded up to 8-12degs depending on year/model for no good reason.
Bob
I believe Harley went to dual plugs to clean up the last bit of combustion for emissions compliance. Not sure if there is power to be had but simply doing a pull with the plug wires pulled from the outer plugs will answer that.
After many years of tuning these v-twins I have yet to see ANY increase from changing from a new HD plugs to any other aftermarket plug.
Also, until 2017, these engines used an ion-sensing anti-knock system that was based partly on sparkplug, wire, and coil resistance so changing to aftermarket stuff doesnt help the system and will tend to mis-report knock and as a result, timing being retarded up to 8-12degs depending on year/model for no good reason.
Bob
I'll agree that the fancy plugs can screw up ion sensing. Also not sure if they help all that much on the M8 dual plug system as the flame front is started from 2 locations. Lean burns, burn slower. 2 plugs speed the combustion process up.. They might help. They night not.
I could see them helping at partial throttle, lean burn, carbed bike or anything that is running lean at partial throttle without ion sensing issues.
Again, I'm impressed with how well the M8s run..
