I just changed plugs and wires yesterday. I went with stock plugs and Symax 8mm red wires. My 96 ci 07 FXSTC has a Stage 1 mod. I gapped the plugs to 38 as Doc recommended. Test ride was AWESOME. She definitely runs better and responded quicker. The plugs I pulled were about 43 so at the max gap. Thanks Doc for YOUR infinite wisdom!
Here's why I disagree with a 10,000 mile spark plug replacement. 1. Engines run closer to the stoichiometric A/F ratio, so plugs stay cleaner. 2. Modern engines have higher ignition voltage, making for a hotter spark and easier to jump the gap. 3. We no longer use lead in the fuel, and fuels are better than those of years past. 4. Engines are better built and have lower blow-by minimizing oil burn and resultant plug contamination. I change mine at 50,000 miles...never a hiccup.
I over looked changing my OEM spark plugs at just under 69K miles. I didn’t notice any performance issues on my then 110” 2015 CVO motor. I plan to change them at 20K miles from now on.
Going to get spark plugs from the dealership right now thank you for sound advice and taking the time out to do these videos they greatly help us who aren't professional mechanics but can at least do minor repairs and upgrades
And do not go to hotter range spark plug tips if your riding style is mostly average speed with the usual blasts for kicks. Like the man said, the lower end of the OEM gap is better.
NGK spark plugs feature what is known as ‘trivalent plating’. This is a silver-or-chrome coloured finish on the threads that is designed to provide corrosion resistance against moisture, chemicals and weathering. The coating also acts as a release agent during spark plug removal. NGK spark plugs are installed at the factory dry, without the use of anti-seize. NGK tech support has received a number of tech calls from installers who have over-tightened spark plugs because of the use of anti-seize. Anti-seize compound can act as a lubricant altering torque values up to 20 percent, increasing the risk of spark plug thread breakage
It's not a bad idea to have some antiseize compound on the thread of the sparkplug, but you have to compensate for the torque-value. This is a good advice you gave. Thank you for sharing your experience and background story. 👍👍👍👍👍. Greetings from The Netherlands
My bike has 9k miles on it. Just added a S&S cam and a Vance and Hines exhaust. Been having a very hard time getting it tuned. Pulled the plugs and the gaps were closed (under .020) not sure how that happened but she runs much better with the proper gap
If gapped correctly and motor tuned probably they should last way longer than 10k. Hell in cars they go 100k plus miles. Could it be you just want to sell us more parts?
As long as the electrode post is flat and square all you need to do is check the gap providing you don't have carb or ignition problems that cause the plug to foul. I think new plugs are way over hyped and just another stealership trying to sell more sh--
One additional comment to spark plug changing is to not over-tighten. It's easy to do. Best is to check the service manual and use a torque wrench. CAUTION: if you use anti-seize as Doc recommended, the torque value in the service manual DOES NOT APPLY. The torque values in the manual are for clean, dry threads with only the oil from manufacture. Anti-seize will cause much higher thread loads by the time the torque value on the wrench is met.
And ..with the extreme heat the anti seize can get down into your cylinder heads not a good thing.. I base this on car racing if you want your plugs to foul extreme temperatures put some anti seize on them
Pick up new plugs today at dealer and they had to stock wires because they carry them in so he then try selling me screaming eagles at $30 I said I'll wait for the stock he thought I was weird but I didn't care I'm starting not like that dealer
My Ultra Limited was getting hard to start at 14,000+ miles. Initially thought it was the battery as it is the original battery on a 2016. Decided to put in new plugs and what a difference. Bike fires right up and the power on the road is back. I didn’t realize the amount of power loss the old plugs were causing. I’m going to go with Doc’s advice and replace the every 10,000 miles from here on out.
Doc I could not have said it any more clearly. Perfect, plus check your wires for being dried out and the boots over the plug. I alsways change them out at 10K but i use NGK and changed out to Harley Fat Wires. Tech tip...carry a spare set in your bags...what $15.00 to save headaches. No brainer
I change mine every 3-5 thousand and even then I notice a difference. Here in New England the weather changes drastically in a day, plus with a Mikuni you be could be lean today and rich tomorrow, add traffic and heat, it’s a recipe for abuse.
Doc, I pu a 2003dyns wide glide with 50+kmiles. I am changing the plugs. But, should I also change the plug wires ? If so, what kind would you recommend? Thanks for your experienced help.you help us hd bike riders so much.
They are $4-$10 bucks each depending on brand and where you buy them. Personally I buy the HD silver and change mine with every oil change. But I also ride my bike almost every day, year round. Take care of your ride and it will last longer.
Doc Harley, One thing you did not discuss was resistor spark plugs. They have a built-in gap also in the ceramic stem. You can’t see that but that gap also wears down and gets round. I usually change mine every oil change. They’re not that expensive and I ain’t doing anything while I’m waiting for the oil to drain.
My comment isn't about this video. Supposedly about 5 years ago Harley did a recall on their saddle bags because they just fell off! Fast forward to today I'm reading forums with people who are losing their bags. I think this is a bit of a liability to harley. I think people who lost a bag should form a group to pressure HD to replace the pins with a different mechanism and compensate people the money they spend replacing them. What is your opinion about this. If it was fixed and they are still falling off, it's not fixed. What if one flew off and killed someone? Who would be liable? Something for them to think about.
Hey Doc Would you mind doing a video explaining the improvements made in the 2024 M8 engine, if any, regarding crankcase breathing and oil getting to the pistons, you’re knowledge, and advice is greatly appreciated
Hate when a manufacturer changes Their maintenance intervals out of nowhere. Nothing has changed except the timing of the maintenance. I replace my spark plugs in my 14’ Street Glide every other oil change. That’s about the 8,000-10,000 mile mark. They are cheap! Why not
You are correct- they are in it for the money. Synthetic oils dont break down they just get dirty. A Harley is just like any other machine and theirs no witchcraft in servicing it. I service my M8 every ten thousand. I changed plugs at 30,000 and they still look ok.
Hi Doc I agree with you, especially for people changing their own. Better performance for less than the price of a value meal, why not? My only thing is my bike has NGK plugs and after talks to NGK they told me no anti-seize because their plugs already have a coating. So I would say check to see if your plugs have a coating before adding anti-seize, could cause you problems over torquing the plugs
Russell Linthicum this is true. I just bought a 2005 Sportster, with 11,000 miles on the clock, on the original front tyre. I’ve just replaced the tyre and the plugs too. Not too sure whether 15 years is a very good service interval though. 🙂
A few reasons: Does your car idle at 900 then accelerate to 6000RPM on a weekly basis? Mine does! Your vehicle is water cooled with control of heat. Harley-Davidson air cooled. Harley-Davison has not redesigned spark plugs to go past 50K. ~ Thanks, Doc
Going on a trip with my 2015 road king. While checking everything the stock 6r12 plugs have about 10,000 on looked good but I had another set of fancy iridium plugs in the toolbox. Tossed them in and bike started better & idled better. Wasn’t even gonna change them but glad I did
Good information. I change my plugs every 10K miles whether they need it or not. I think my service manual for my 2016 HD Streetglide Special says every 35K miles which makes no since.
Check plug tops, make sure they are tight. Anti seize threads, and a little dielectric grease on plug top and a little in the boot for ease of slip on. Champion Spark Plug Chart shows you how "Spark plugs tell a story", you can find them online, or buy one and stick up in the garage.
Doc....thank you for all your tutorial & how to video's. Spark plug question. 2012 Street Glide,stock 103, just turned 40k miles. I use the factory recommended plugs. On recent 40k service at dealership,tech showed me my 5k mileage plugs installed at 35k service) and very top of outer electrode (ground strap),had white deposit. Bike always ran and performed very well. Center electrode had normal wear,no build up. I changed fueling station,but kept using 93 octane. Tech said cylinders and piston tops look good. Any knowledge on why top of electrode had white deposit? Oil migration? (piston rings? valve stem seal /seats? head gasket?) Should I request a compression test on each cylinder? Is it too much to change plugs every 5k miles now that mileage on bike is climbing?
Doc, I know that I am a bit late to everything. I have a 03 fat boy. So I am new . I love it as everyone else does. I want to thank you for your videos. You are giving me a ton of information. No way can I ever thank you enough Sir!!!
Thank you for sparkplug tips. My 103 has a stage one kit currently which has been tuned at Harley Davidson so I recently changed my sparkplugs on my 2015 Ultra Limited to Screaming Eagle sparkplugs and also upgraded my plug wires to the Screaming Eagle plug wires. Hoping for a little more performance until I go to the next stage 2 kit.
Good video. I notice many Harley riders spare little expense on their "babies". Most NEVER wait until the mileage specified in the maintenance chart, yet every other machine they own they won't replace a part until it breaks. The arguments that "plugs are cheap", "cheap insurance", "why not just replace them?" makes little sense. If a spark plug cannot last more than 2,000 miles, you bought a crap plug! In the video he refers to the fact that Harley has extended the mileage interval for spark plug replacement and that is for a good reason. "Doc Harley" states the plug is exactly the same. I cannot say with certainty that he is incorrect, but as an auto technician I know plugs have evolved immensely over the last few years. He is absolutely correct when he said the electrodes erode and the gap widens, but the metal which was used was steel or copper. THOSE plugs lasted 30,000 miles in a car. Today the mentality of plug design is to treat the 2 electrodes with platinum or iridium. These 2 precious metals are able to sustain much more abuse without wearing down. Sure, a 2 cylinder engine will fire the plug more often than my Dodge pick up V8, but come on, 2,000 miles!!!? I have much better things to do and remember than to change the Iridium plugs in my Dyna every 2,000 miles. If you're bored and want to "FIX" something on your scooter, check the tire pressure against factory recommended psi. I bet they need air.
Awesome video Doc. I have a question. I have a 2022 Harley Davidson XL883N Iron 883 and was wondering what brand or name of spark plug should I be using in my Iron 883 and what should be the gap?
It amazes me how many people don't know how to do simple maintenance. Thanks for helping the world be a little bit more aware of proper care of their scooters
Iridium plugs have an anode and electrode so hard, they don't wear nearly as fast. Their gap stays constant. Also, torque down your plugs properly. My 1200 Sporty starts right up, cold or hot.
I just bought a 91 Harley Sportster XLH 883 and it will foul the plugs within 10 miles black shut not wet why do you think the problem is I got a new carburetor I'm going to try
Just a few suggestions. Check intake manifold rubber seals for leaking. Stock spark plugs? Aftermarket can be wrong. Choke sticking on? Ignition coil weak? Stock carb or someone substituted a performance carb that is not jetted for the 883……Doc
Hi doc ! Is it true when we re replacing the spark plug cable, for the 10mm cable on a M8, it's better to replaced the spark plug for screaming eagle performance or it's bulls... Thanks !
I got 23,500 miles on my RG Never Changed yet 😳 My Dealers never told me to change They Perform all Services on my Bike since day One , Never Changed Very Sad
So I have a 2012 FLHX Street Glide,does it only have 2 plugs the manual I was looking at said it has 4,remove the tank to get the other two ???? Thanks for your answer Sam
My own experience on my 2007 Ultra I installed true duel exhaust, Vance and Hines mufflers, high intake air and with this a Fuel pack. I have found that between 6 to 10 thousand miles my check engine ligh comes on and takes longer to go off. When I change spark plugs this remedies the problem. Change Spark Plugs Spark!!!
Great tip Doc. plus spark plugs (not talking about the ones that are hyped to boost your HP rating by 50%, or they are so intense they would ignite space shuttle fuel) are so inexpensive, would only make sense to put in new plugs even at 6 to 8 thousand miles. Your Harley's worth it!!!
Hey doc how are you? Regarding to your video witch as alway it’s very interesting and teachfully, I would like to ask you, what about the coils? I recently bought a KV tester and yes, I could test my spark plugs from 10 to 40 KV (understanding that any reading between 30-40 KV its a good indication of the coil condition) but I really would like to know your experience about this in case you use it! Once again, thank you very much for “taking me out the savage” and best regards from Mexico! Paco Balmori
Priceless information, as is your custom Sir. However, I was put off by the increased change interval HD recommendation…it should be shorter than 10K. If a 10K plugs is in such a condition that a simple visual inspection confirms, “definitely needs replacing” then it stands to reason, that a shorter interval is warranted. “PMS” in the U.S. Navy means, Preventive Maintenance System, the thought 💭 process is to KEEP equipment AT peak level performance while heading off failure. Doc, in my humble opinion PMS applied to HD spark plugs would suggest a 5K inspection and/or change. 2020 Fat Boy
I service my own Harleys. On my old 74 sportster I service it every 5 thousand miles. On my new trike with the M8 engine I service it every 10 thousand miles. With the new synthetic technology I feel you could safely go 20 thousand. The main thing is that your synthetic lubricants be at their proper levels. I dont change plugs at all until the bike tells me it's time. If it ain't broke dont fix it.
Hi Thanks for your interesting videos. How about iridium sparkplugs? My ECU is of S&S VFI, with knock detection mounted to the rear head. So no need for ION. What do tell about those plugs? Thanks Doc. Greetings Peder
Those spark plugs are made of the finest material. You have a rare system there. I have not had the pleasure to work with and understand everything about it. Have opinions but the choice is yours…..Doc
@@LowCountryHarleyDavidson Thanks mr Doc. Trial and error. I will at least try them. Thanks for your fast reply. Im living in Sweden. 🇸🇪 Will put the ride on a Dyno now at Tuesday. I have done a lot of changing on the fuel map. But you see S&S oxygen sensors are of the narrow band. They can not do its job. So now I have shut down the closed loop and the adaptiv maps. Dyno run is whats left. Auto tune even with wide band sensors, what I have learned, is they need dyno to to get the fine adjustment. My thoughts. Thanks again for your fine and tutorial videos. Greetings Peder 😊👍🏻😅🇸🇪🇺🇸
I know it’s a 2 year old video but just wanted to add according to the service interval per manufacture specifications on my 15 Road Glide 103HO it’s replace spark plugs every 2 years/30,000 miles which ever comes first. Yes I strongly agree with you keep it simple what you take out is what you put back in .... unless your doing major engine modifications such as altering the compression, etc than it starts to matter.
Mileage is important. But let’s just say you do short trips. A lot of short trips without the motor getting to full temp. While cold the fuel mapping is adding extra fuel. Add this multiple times and the spark plugs don’t have a chance to burn clean….Doc
I changed mine with OEM plugs from the dealer and air filter. I lost 40 miles to a tank of gas (5 gallons) in my ‘05 Heritage, changed around 43k miles. Should I have changed my plug wires, too? Weird that I had a pretty drastic mileage drop. One of the plugs I changed was even gapped wrong (small gap
Need advice. I have a 2006 custom sportster. I changed the plugs the other day. I started it up, no problem. I touched the rubber boot on the plugs with my finger and got shocked. I can’t imagine the wires are bad as they only have 1200 miles on them plus they weren’t bad before I touched them. Could I have done something wrong? I used Ngk iridium
First to check is the cap at the top of the spark plugs. Some are made to come off. Tighten if loose. Make sure plug wires are pushed in coil all the way. Mileage is low but 14 years of out in the weather can break down wires. I would replace them. ~ Doc
Cost and my belief that most don’t use a torque wrench when installing spark plugs so over tightening a steel threads into an aluminum part will eventually damage the head. Every 10K is good enough in my opinion…..Doc
I was wondering the same thing. My old Yamaha Star 950 recommend 8k on the plug replacement but then I got my 2014 Street Glide and the OM said 30k.. Why the big difference? It's still a V-twin design.
Most all newer spark plugs from 2005 on up have an Iridium coating on the gap arm. Iridium lasts 10X longer because the metal can withstand 10X the heat than older spark plugs and why they first used them in MotoGP and is also why Harley changed the interval time to change plugs. I purchased new plugs for My 08 Dyna, Took the old ones out after 14k miles, they still looked bran new and I have no running issues so I didn't swap them out. Especially since with Iridium added to the sparks plugs they are 3X the cost of older plugs. SO yes they did actually change the design to the spark plugs. Now in 2024 all manufacturers use Iridium coated metal on their spark plugs, even on small engine plugs. Not a rant just an FYI. Video is 6 years old I know but allot of people don't know this info. Look at the box the spark plug came in, it will say Iridium coated...
Never put anti seize on spark plugs. It will let you tighten them down farther than you’re supposed to. It will also easily strip an aluminum head with a steel threaded spark plug. Just warm the bike up when removing and they will come out easily
When I was in auto shop on high school (1000 years ago) I was assigned to rebuild an old Maytag GAS POWERED washing machine engine. The spark plug was dated 1918 and it was a fat little guy. Here's the big thing; it had a little 8-bladed fan on the bottom, NOT the typical spark-gap thing (I'm sure there's a name for it but I don't know what it is) like today. Have you ever seen a spark plug like that? BTW, I had to use it and it still worked like it was brand new!
Not sure you’re correct on the anti seize torque statement. I twisted a wrench for Cummins, and antiseized every thing that I might see again some day. I always went by torque specs and never pulled a thread.
On an older Cummings 855 if you torqued the head bolts with never seize you could crack the counter bore. That's one of the reasons they came out with water passage inserts. Torque values only apply with the specified lube
Heres my advice to harley owners. Have a pouch or use your saddle bags and keep four new spark plugs and a ratchet and socket in any harley you use. When you start them cold and one cylinder doesnt fire until it runs for 10 seconds (which is common), change the plugs. Some will miss out and you have to keep reving them when theyre cold, change the plugs. For the record I have had the best luck with auto lite spark plugs. You have to cross reference them to know what size, as my twin cam uses a different size than my evos. Always also be sure to compare the reach of a plug with the old plug, because if your reach is longer you can knock a hole in a piston top or if too short can result in carbon. Also, keep a round plug gap tool on your key ring, so you can gap them
@@LowCountryHarleyDavidson Havent learned that much about the M8 yet though. But from what Ive seen I think the M8 version appears better mechanically than the TC B version due to gear to counter balancers instead of the guide and chain
Good info .Spark plugs can be cleaned and gap can adjusted. Riding for over 25 years. Plugs have never been a problem. I only had one ever fail completely. A little maintenance goes a long way . .
I just changed plugs and wires yesterday. I went with stock plugs and Symax 8mm red wires. My 96 ci 07 FXSTC has a Stage 1 mod. I gapped the plugs to 38 as Doc recommended. Test ride was AWESOME. She definitely runs better and responded quicker. The plugs I pulled were about 43 so at the max gap. Thanks Doc for YOUR infinite wisdom!
I own an aftermarket shop...this guy is just good, I have my customers go to youtube while we are working on their bike.Plus he is articulate.
NGK, gapped at .040, change every 5000 miles. Cant go wrong.
There is nothing better than the stock oem plugs. But if I can’t get them, then ngk.
He's like the Alton Brown of Harleys
Spot on dude
Here's why I disagree with a 10,000 mile spark plug replacement.
1. Engines run closer to the stoichiometric A/F ratio, so plugs stay cleaner.
2. Modern engines have higher ignition voltage, making for a hotter spark and easier to jump the gap.
3. We no longer use lead in the fuel, and fuels are better than those of years past.
4. Engines are better built and have lower blow-by minimizing oil burn and resultant plug contamination.
I change mine at 50,000 miles...never a hiccup.
I over looked changing my OEM spark plugs at just under 69K miles. I didn’t notice any performance issues on my then 110” 2015 CVO motor. I plan to change them at 20K miles from now on.
Going to get spark plugs from the dealership right now thank you for sound advice and taking the time out to do these videos they greatly help us who aren't professional mechanics but can at least do minor repairs and upgrades
And do not go to hotter range spark plug tips if your riding style is mostly average speed with the usual blasts for kicks. Like the man said, the lower end of the OEM gap is better.
NGK spark plugs feature what is known as ‘trivalent plating’. This is a silver-or-chrome coloured finish on the threads that is designed to provide corrosion resistance against moisture, chemicals and weathering. The coating also acts as a release agent during spark plug removal. NGK spark plugs are installed at the factory dry, without the use of anti-seize. NGK tech support has received a number of tech calls from installers who have over-tightened spark plugs because of the use of anti-seize. Anti-seize compound can act as a lubricant altering torque values up to 20 percent, increasing the risk of spark plug thread breakage
Thank you for sharing this important information. I am concerned about steal going into aluminum without lube🤷♂️…Doc
It's not a bad idea to have some antiseize compound on the thread of the sparkplug, but you have to compensate for the torque-value. This is a good advice you gave. Thank you for sharing your experience and background story. 👍👍👍👍👍. Greetings from The Netherlands
My bike has 9k miles on it. Just added a S&S cam and a Vance and Hines exhaust. Been having a very hard time getting it tuned. Pulled the plugs and the gaps were closed (under .020) not sure how that happened but she runs much better with the proper gap
If gapped correctly and motor tuned probably they should last way longer than 10k. Hell in cars they go 100k plus miles. Could it be you just want to sell us more parts?
Correct sir!. The platinum plugs in my Chevy truck have gone 60,000 miles and it's running great. Why mess with them. ?
Great info. Thanks. Don't forget about the crush washer, needs replaced when you dress the plug and adjust the gap if you reuse the same plug.
Thank you Doc, I was getting tired of different dealerships telling that it's normal on a 2 month old bike. 2021 streetbob with 8200 miles on.
As long as the electrode post is flat and square all you need to do is check the gap providing you don't have carb or ignition problems that cause the plug to foul. I think new plugs are way over hyped and just another stealership trying to sell more sh--
Doc, thanks so much! My bike has had a hiccup every once in a while lately. I’m checking the spark plug when I get home
and survey said ?
One additional comment to spark plug changing is to not over-tighten. It's easy to do. Best is to check the service manual and use a torque wrench. CAUTION: if you use anti-seize as Doc recommended, the torque value in the service manual DOES NOT APPLY. The torque values in the manual are for clean, dry threads with only the oil from manufacture. Anti-seize will cause much higher thread loads by the time the torque value on the wrench is met.
And ..with the extreme heat the anti seize can get down into your cylinder heads not a good thing.. I base this on car racing if you want your plugs to foul extreme temperatures put some anti seize on them
Pick up new plugs today at dealer and they had to stock wires because they carry them in so he then try selling me screaming eagles at $30 I said I'll wait for the stock he thought I was weird but I didn't care I'm starting not like that dealer
My Ultra Limited was getting hard to start at 14,000+ miles. Initially thought it was the battery as it is the original battery on a 2016. Decided to put in new plugs and what a difference. Bike fires right up and the power on the road is back. I didn’t realize the amount of power loss the old plugs were causing. I’m going to go with Doc’s advice and replace the every 10,000 miles from here on out.
Okay. Change plugs at least every year, so do it when I change the battery in my key fobs, on my birthday. 😎
may I add one thing to this. When you change your plugs use a torque wrench and set them to the proper torque.
and Use anti seize on every spark plug
I have a 2015 Limited Low. The owners manual says change every two years or 30k miles, whichever comes first.
Doc Holiday dude is cool 😎👍🏼🏍
Great tips !
Doc I could not have said it any more clearly. Perfect, plus check your wires for being dried out and the boots over the plug. I alsways change them out at 10K but i use NGK and changed out to Harley Fat Wires. Tech tip...carry a spare set in your bags...what $15.00 to save headaches. No brainer
I change mine every 3-5 thousand and even then I notice a difference. Here in New England the weather changes drastically in a day, plus with a Mikuni you be could be lean today and rich tomorrow, add traffic and heat, it’s a recipe for abuse.
...and no cross threading when you screw in your plugs.
Doc, I pu a 2003dyns wide glide with 50+kmiles. I am changing the plugs. But, should I also change the plug wires ? If so, what kind would you recommend?
Thanks for your experienced help.you help us hd bike riders so much.
Yes, If your bike is carb go with Magnacore or Taylor if your bike is fuel injected go with HD factory...Doc
@@LowCountryHarleyDavidson thanks again doc.
Wow! Got me thinking, 35,000 miles and don’t remember ever having them changes. Thanks
Jesus
They are $4-$10 bucks each depending on brand and where you buy them. Personally I buy the HD silver and change mine with every oil change. But I also ride my bike almost every day, year round. Take care of your ride and it will last longer.
I was considering getting a more expensive plug but I will take your advice.
Thanks for watching Mike….Doc
Doc Harley, One thing you did not discuss was resistor spark plugs. They have a built-in gap also in the ceramic stem. You can’t see that but that gap also wears down and gets round. I usually change mine every oil change. They’re not that expensive and I ain’t doing anything while I’m waiting for the oil to drain.
My comment isn't about this video. Supposedly about 5 years ago Harley did a recall on their saddle bags because they just fell off! Fast forward to today I'm reading forums with people who are losing their bags. I think this is a bit of a liability to harley. I think people who lost a bag should form a group to pressure HD to replace the pins with a different mechanism and compensate people the money they spend replacing them. What is your opinion about this. If it was fixed and they are still falling off, it's not fixed. What if one flew off and killed someone? Who would be liable? Something for them to think about.
Hey Doc
Would you mind doing a video explaining the improvements made in the 2024 M8 engine, if any, regarding crankcase breathing and oil getting to the pistons, you’re knowledge, and advice is greatly appreciated
Hate when a manufacturer changes Their maintenance intervals out of nowhere. Nothing has changed except the timing of the maintenance. I replace my spark plugs in my 14’ Street Glide every other oil change.
That’s about the 8,000-10,000 mile mark.
They are cheap!
Why not
re gap usually helps...also clean them.Every 10,000 mi. is just selling parts and service.Don't drink the kool-aid
You are correct- they are in it for the money. Synthetic oils dont break down they just get dirty. A Harley is just like any other machine and theirs no witchcraft in servicing it. I service my M8 every ten thousand. I changed plugs at 30,000 and they still look ok.
Hi Doc I agree with you, especially for people changing their own. Better performance for less than the price of a value meal, why not? My only thing is my bike has NGK plugs and after talks to NGK they told me no anti-seize because their plugs already have a coating. So I would say check to see if your plugs have a coating before adding anti-seize, could cause you problems over torquing the plugs
No offense but you could do Whacky morning FM radio shows w/ that radio-trained voice ;)
_OK, Shuttin' the F up now....changing da plugs boss_
My service manual says change at 20K - My dyna is at 10K right now. I suppose I should check/change my plugs based on this video. Thanks Doc.
With the price of gasoline and the price of parts I change my spark plugs every oil change at 5000 miles and always check the gap
When you change your front tire change your spark plugs too.Thanks for the information, it's right on.
Russell Linthicum this is true. I just bought a 2005 Sportster, with 11,000 miles on the clock, on the original front tyre. I’ve just replaced the tyre and the plugs too. Not too sure whether 15 years is a very good service interval though. 🙂
I don't understand why my car's iridium plugs are good for 100,000+ miles but my Harley needs plugs every 5000 miles.
A few reasons: Does your car idle at 900 then accelerate to 6000RPM on a weekly basis? Mine does! Your vehicle is water cooled with control of heat. Harley-Davidson air cooled. Harley-Davison has not redesigned spark plugs to go past 50K. ~ Thanks, Doc
Going on a trip with my 2015 road king. While checking everything the stock 6r12 plugs have about 10,000 on looked good but I had another set of fancy iridium plugs in the toolbox. Tossed them in and bike started better & idled better. Wasn’t even gonna change them but glad I did
Good information. I change my plugs every 10K miles whether they need it or not. I think my service manual for my 2016 HD Streetglide Special says every 35K miles which makes no since.
Check plug tops, make sure they are tight. Anti seize threads, and a little dielectric grease on plug top and a little in the boot for ease of slip on. Champion Spark Plug Chart shows you how "Spark plugs tell a story", you can find them online, or buy one and stick up in the garage.
A good follow up Tech Tip….Doc
Doc....thank you for all your tutorial & how to video's.
Spark plug question. 2012 Street Glide,stock 103, just turned 40k miles.
I use the factory recommended plugs.
On recent 40k service at dealership,tech showed me my 5k mileage plugs installed at 35k service) and very top of outer electrode (ground strap),had white deposit.
Bike always ran and performed very well. Center electrode had normal wear,no build up. I changed fueling station,but kept using 93 octane. Tech said cylinders and piston tops look good.
Any knowledge on why top of electrode had white deposit? Oil migration? (piston rings? valve stem seal /seats? head gasket?) Should I request a compression test on each cylinder?
Is it too much to change plugs every 5k miles now that mileage on bike is climbing?
Yes sir great tip . I change mine every year at beginning of the riding season .... I live in the north ....lol
Yep do the spark plug replacement at every oil/filter change too 👍
Doc, I know that I am a bit late to everything. I have a 03 fat boy. So I am new . I love it as everyone else does. I want to thank you for your videos. You are giving me a ton of information. No way can I ever thank you enough Sir!!!
Thank you for your support Dale....Doc
Thank you for sparkplug tips. My 103 has a stage one kit currently which has been tuned at Harley Davidson so I recently changed my sparkplugs on my 2015 Ultra Limited to Screaming Eagle sparkplugs and also upgraded my plug wires to the Screaming Eagle plug wires. Hoping for a little more performance until I go to the next stage 2 kit.
Why check them, there cheap, just replace em....
Excellent... Thank you sir 👍🏾
Your dad sounds like a smart man, he taught you well. Now you get to teach us a thing or two about Harleys. Great video Doc, see you next time!
Thanks 👍
Agreed ,for all you young guys out there ,try starting a kick start 6 volt
FL Panhead with bad plugs .
Been there, got the T-shirt and larger right calf.....Doc
Good video. I notice many Harley riders spare little expense on their "babies". Most NEVER wait until the mileage specified in the maintenance chart, yet every other machine they own they won't replace a part until it breaks. The arguments that "plugs are cheap", "cheap insurance", "why not just replace them?" makes little sense. If a spark plug cannot last more than 2,000 miles, you bought a crap plug!
In the video he refers to the fact that Harley has extended the mileage interval for spark plug replacement and that is for a good reason. "Doc Harley" states the plug is exactly the same. I cannot say with certainty that he is incorrect, but as an auto technician I know plugs have evolved immensely over the last few years. He is absolutely correct when he said the electrodes erode and the gap widens, but the metal which was used was steel or copper. THOSE plugs lasted 30,000 miles in a car. Today the mentality of plug design is to treat the 2 electrodes with platinum or iridium. These 2 precious metals are able to sustain much more abuse without wearing down. Sure, a 2 cylinder engine will fire the plug more often than my Dodge pick up V8, but come on, 2,000 miles!!!? I have much better things to do and remember than to change the Iridium plugs in my Dyna every 2,000 miles. If you're bored and want to "FIX" something on your scooter, check the tire pressure against factory recommended psi. I bet they need air.
He didn’t say change them every 2000 miles........he said 10,000 miles, big difference.
Excellent explanations Doc! That'll keep it runnin right. 👊
Awesome video Doc. I have a question. I have a 2022 Harley Davidson XL883N Iron 883 and was wondering what brand or name of spark plug should I be using in my Iron 883 and what should be the gap?
Go to your local dealer and buy genuine HD Spark plugs. Gap .038-.042….Doc
Good on you thanks, cheapest bang for your buck ,than any other thing ,why not
It amazes me how many people don't know how to do simple maintenance. Thanks for helping the world be a little bit more aware of proper care of their scooters
Iridium plugs have an anode and electrode so hard, they don't wear nearly as fast. Their gap stays constant. Also, torque down your plugs properly. My 1200 Sporty starts right up, cold or hot.
Thanks for sharing your experience….Doc
I just bought a 91 Harley Sportster XLH 883 and it will foul the plugs within 10 miles black shut not wet why do you think the problem is I got a new carburetor I'm going to try
Just a few suggestions. Check intake manifold rubber seals for leaking.
Stock spark plugs? Aftermarket can be wrong. Choke sticking on? Ignition coil weak? Stock carb or someone substituted a performance carb that is not jetted for the 883……Doc
Hi doc ! Is it true when we re replacing the spark plug cable, for the 10mm cable on a M8, it's better to replaced the spark plug for screaming eagle performance or it's bulls...
Thanks !
Bull…..Doc
I got 23,500 miles on my RG
Never Changed yet 😳
My Dealers never told me to change
They Perform all Services on my Bike since day One , Never Changed
Very Sad
Many follow HD recommend 50K change.
Me….Really?…..Doc
So I have a 2012 FLHX Street Glide,does it only have 2 plugs the manual I was looking at said it has 4,remove the tank to get the other two ????
Thanks for your answer
Sam
Your year has a Twin Cam motor with just 2 spark plugs. You have the wrong manual…..Doc
My own experience on my 2007 Ultra I installed true duel exhaust, Vance and Hines mufflers, high intake air and with this a Fuel pack. I have found that between 6 to 10 thousand miles my check engine ligh comes on and takes longer to go off. When I change spark plugs this remedies the problem. Change Spark Plugs Spark!!!
Spark plugs are cheap. No reason not to change them.
Great tip Doc. plus spark plugs (not talking about the ones that are hyped to boost your HP rating by 50%, or they are so intense they would ignite space shuttle fuel) are so inexpensive, would only make sense to put in new plugs even at 6 to 8 thousand miles. Your Harley's worth it!!!
such an informative video, I needed this info.
thank you sir !
Hey doc how are you? Regarding to your video witch as alway it’s very interesting and teachfully, I would like to ask you, what about the coils? I recently bought a KV tester and yes, I could test my spark plugs from 10 to 40 KV (understanding that any reading between 30-40 KV its a good indication of the coil condition) but I really would like to know your experience about this in case you use it! Once again, thank you very much for “taking me out the savage” and best regards from Mexico! Paco Balmori
i change plugs every fall when i put the bike away for winter (OHIO) along with all
three hole of oil....put on about 6K a year....good insurance...
Priceless information, as is your custom Sir. However, I was put off by the increased change interval HD recommendation…it should be shorter than 10K. If a 10K plugs is in such a condition that a simple visual inspection confirms, “definitely needs replacing” then it stands to reason, that a shorter interval is warranted. “PMS” in the U.S. Navy means, Preventive Maintenance System, the thought 💭 process is to KEEP equipment AT peak level performance while heading off failure. Doc, in my humble opinion PMS applied to HD spark plugs would suggest a 5K inspection and/or change. 2020 Fat Boy
You are so correct....Doc
I service my own Harleys. On my old 74 sportster I service it every 5 thousand miles. On my new trike with the M8 engine I service it every 10 thousand miles. With the new synthetic technology I feel you could safely go 20 thousand. The main thing is that your synthetic lubricants be at their proper levels. I dont change plugs at all until the bike tells me it's time. If it ain't broke dont fix it.
I change my plugs every spring then halfway through the riding season, 2 oil changes @ 3500 miles each.
Wow……Doc
If my bike starts up at 750 rpm and slowly gets to 1000 rpm and stalls when I hit the the clutch and stop at a light could that be spark plug ?
Part of it because your intake seals have gone bad so the wrong amount of fuel is dumping on them….Doc
If I could get all of you guys 5,000 mile old synthetic lubes and spark plugs I would maintain my Harleys for free !
Hi Thanks for your interesting videos. How about iridium sparkplugs? My ECU is of S&S VFI, with knock detection mounted to the rear head. So no need for ION. What do tell about those plugs? Thanks Doc. Greetings Peder
Those spark plugs are made of the finest material. You have a rare system there. I have not had the pleasure to work with and understand everything about it. Have opinions but the choice is yours…..Doc
@@LowCountryHarleyDavidson Thanks mr Doc. Trial and error. I will at least try them. Thanks for your fast reply. Im living in Sweden. 🇸🇪 Will put the ride on a Dyno now at Tuesday. I have done a lot of changing on the fuel map. But you see S&S oxygen sensors are of the narrow band. They can not do its job. So now I have shut down the closed loop and the adaptiv maps. Dyno run is whats left. Auto tune even with wide band sensors, what I have learned, is they need dyno to to get the fine adjustment. My thoughts. Thanks again for your fine and tutorial videos. Greetings Peder 😊👍🏻😅🇸🇪🇺🇸
I know it’s a 2 year old video but just wanted to add according to the service interval per manufacture specifications on my 15 Road Glide 103HO it’s replace spark plugs every 2 years/30,000 miles which ever comes first. Yes I strongly agree with you keep it simple what you take out is what you put back in .... unless your doing major engine modifications such as altering the compression, etc than it starts to matter.
Why time vs mileage? Now it’s 2 years vs mileage. I will only have 2000 miles at two years? I will have to do it to maintain the warranty.
Mileage is important. But let’s just say you do short trips. A lot of short trips without the motor getting to full temp. While cold the fuel mapping is adding extra fuel. Add this multiple times and the spark plugs don’t have a chance to burn clean….Doc
Decreased mileage, rough idle, simple stuff
I changed mine with OEM plugs from the dealer and air filter. I lost 40 miles to a tank of gas (5 gallons) in my ‘05 Heritage, changed around 43k miles. Should I have changed my plug wires, too? Weird that I had a pretty drastic mileage drop. One of the plugs I changed was even gapped wrong (small gap
Agree, weird that you had a pretty drastic mileage drop. There has to be more to the story...Doc
Correct flame kernel without straining secondary windings is key! Good one Doc! ✌🏻
I really don't understand what you're saying could you expand on that
You are very logical and dead on accurate
You change spark plugs because after about thirty thousand kilometres the electrodes are about worn out.
grate advice .. spark plugs are so overlooked now days.
Need advice. I have a 2006 custom sportster. I changed the plugs the other day. I started it up, no problem. I touched the rubber boot on the plugs with my finger and got shocked. I can’t imagine the wires are bad as they only have 1200 miles on them plus they weren’t bad before I touched them. Could I have done something wrong? I used Ngk iridium
First to check is the cap at the top of the spark plugs. Some are made to come off. Tighten if loose. Make sure plug wires are pushed in coil all the way. Mileage is low but 14 years of out in the weather can break down wires. I would replace them. ~ Doc
Low Country Harley-Davidson thank u. I’ll do that
Spark plugs are not expensive. Why not change every time you change the oil?
Cost and my belief that most don’t use a torque wrench when installing spark plugs so over tightening a steel threads into an aluminum part will eventually damage the head. Every 10K is good enough in my opinion…..Doc
Thanks Doc! Perfect timing, I’m changing my plugs on my Iron 883 this week 👍👍
Great information - but this should apply to any motor.
I was wondering the same thing.
My old Yamaha Star 950 recommend 8k on the plug replacement but then I got my 2014 Street Glide and the OM said 30k.. Why the big difference? It's still a V-twin design.
My bike isn't at 10000 miles yet but plugs are rusty, so should I clean them or replace them?
Most all newer spark plugs from 2005 on up have an Iridium coating on the gap arm. Iridium lasts 10X longer because the metal can withstand 10X the heat than older spark plugs and why they first used them in MotoGP and is also why Harley changed the interval time to change plugs. I purchased new plugs for My 08 Dyna, Took the old ones out after 14k miles, they still looked bran new and I have no running issues so I didn't swap them out. Especially since with Iridium added to the sparks plugs they are 3X the cost of older plugs. SO yes they did actually change the design to the spark plugs. Now in 2024 all manufacturers use Iridium coated metal on their spark plugs, even on small engine plugs. Not a rant just an FYI. Video is 6 years old I know but allot of people don't know this info. Look at the box the spark plug came in, it will say Iridium coated...
I will look at this. Please send information and reference to my email so I can learn….Doc
Never put anti seize on spark plugs. It will let you tighten them down farther than you’re supposed to. It will also easily strip an aluminum head with a steel threaded spark plug. Just warm the bike up when removing and they will come out easily
I am sorry i disagree....Doc
When I was in auto shop on high school (1000 years ago) I was assigned to rebuild an old Maytag GAS POWERED washing machine engine. The spark plug was dated 1918 and it was a fat little guy. Here's the big thing; it had a little 8-bladed fan on the bottom, NOT the typical spark-gap thing (I'm sure there's a name for it but I don't know what it is) like today. Have you ever seen a spark plug like that? BTW, I had to use it and it still worked like it was brand new!
Thanks for sharing. I have a few unique spark plugs but none with a fan…Doc
What is the proper torque specification to torque the spark plug down to
There is a reason I don’t quote torque specks. A Harley-Davidson 45 is greatly different than a M8…..Doc
@@LowCountryHarleyDavidson Thank you for the reply Doc. I have a 09 Road king with a 96 CID engine. Hope your day is good Sir.
Not sure you’re correct on the anti seize torque statement. I twisted a wrench for Cummins, and antiseized every thing that I might see again some day. I always went by torque specs and never pulled a thread.
I drop the torque value by 5 -10 with anti-sneeze.... done it for years on cars, truck & tractor engines and Never fouled a plug with anti-sneeze...
On an older Cummings 855 if you torqued the head bolts with never seize you could crack the counter bore. That's one of the reasons they came out with water passage inserts. Torque values only apply with the specified lube
Heres my advice to harley owners. Have a pouch or use your saddle bags and keep four new spark plugs and a ratchet and socket in any harley you use. When you start them cold and one cylinder doesnt fire until it runs for 10 seconds (which is common), change the plugs. Some will miss out and you have to keep reving them when theyre cold, change the plugs. For the record I have had the best luck with auto lite spark plugs. You have to cross reference them to know what size, as my twin cam uses a different size than my evos. Always also be sure to compare the reach of a plug with the old plug, because if your reach is longer you can knock a hole in a piston top or if too short can result in carbon. Also, keep a round plug gap tool on your key ring, so you can gap them
Earl it sounds like you could write a book on the knowledge you have gathered over the years of riding. Thanks for sharing..Doc
@@LowCountryHarleyDavidson Havent learned that much about the M8 yet though. But from what Ive seen I think the M8 version appears better mechanically than the TC B version due to gear to counter balancers instead of the guide and chain
Keep up the great work on all these videos Doc!!! Great feedback, we appreciate you boss 🫡
Sparkplugs don't "take" voltage, they recieve it and have to deal with it. So, they gona react faster when in good condition.
my engine keeps sparking. like sparks flying on my pants. any tips?
Really? Wiring is loose or a metal part on the bike is loose coming in contact with wires. Please stop riding and find/Fix this….Doc
Good info .Spark plugs can be cleaned and gap can adjusted. Riding for over 25 years. Plugs have never been a problem. I only had one ever fail completely. A little maintenance goes a long way .
.
Great point....Doc
hello doc !!what about indexing spark plugs,
Loved performing this when racing but for the street🤷♂️…..Doc
Love your videos… 🔥🔥🔥changing mine this week jus hit 10k
Doc Harley I am from Brasil we love your videos. On my next trip to usa ill visit your Store, and i would like to takea picture with you.
He's a genuine HD tech............ so it's gonna cost ya!! ;)
"Highlighted reply" HAHAHAHAH! crack me up!!
About $65.00 per half hour, NYC.
If your bike is hard to start, you may want to take apart and clean your starter.
A possible option depending on age and condition of bike….Doc