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@@ramonazteca252 You get it! Thats all Steve was trying to say and it flew over many peoples heads. He only said if it doesn't start, don't spend the day trying to set the plug gap because its probably something else. Then these jackasses are on here talking about multi cylinder race engines with fuel mileage and horsepower ratings. Unbelievable...
It's true that a wider gap will also work especially if the engine gives a good strong spark but the larger plasma arch will eat away at the electrodes much quicker . The spark gap is a compromise between the two . That's what I learnt in my motorcycle racing days . If the gap is too small small pieces of vaporized metal and carbon will build between the gap and eventually short it .
I am always amazed at how many people talk about changing their sparkplugs every year or even less. My 2011 ford Ranger with 32000 miles on it has a replacement recommendation of 105000 miles. I am however happy that they support our sparkplug manufacturers and keep them in business.
If the gap is too tight the plugs can foul easily and you can have no spark until they are cleaned. Too wide and it may not work with a weak coil. It's not critical but it's best to have them gapped at 25 to 30 thou or what the maker says.
It's good to know that the gap isn't that critical! The specs sure are splitting hairs usually. But. Now I want to see Project Farm test a variety of different gaps for fuel efficiency, torque and how they perform after a longer duration and get sooty :-)
Gaps are more important on multi cylinder engines where misfiring can occur. Single cylinders don’t care as much but may lose power and efficiency if too small or large a gap. Cool vid Steve!
I agree especially on older style ignition systems because there are many more gaps than just the spark plug ei: points gap, distributor to distributor rotor gap, spark plug gap then factor in all the places that you can have a bad connection coil to coil wire, coil wire to distributor, distributor wire to spark plug wire. These all add up and if there is too much gap the ignition system cannot overcome all of them then you have driveability issues.
Last month I was mowing with my briggs and I shut it off halfway through the job to get myself a drink. It was off maybe 3 minutes tops. I damn near wore myself out pull starting it, when the damn thing never fails to start on the first pull. Pulled the spark plug and held it against the block while I turned the engine over to check for spark - none. Pulled the grounding wire off the coil to make sure it was not the issue - still no spark. I was ready to order a new coil when I decided to inspect the spark plug electrode with a magnifying glass. There was an ultra thin particle bridging the gap. I have no idea where it came from, or what it was made of, but assumed it was causing a short. I verified it was shorted with my multimeter. I used a razor blade to remove the particle, reinstalled the plug and she fired up on the first pull, as it always has. I had witnessed this phenomenon twice now, the first time a few years back with my string trimmer.
There is some carbon that forms in the top of the cylinder (the head) - you see it if you pull the head. Once in a while the running of the engine might break off a flake of that carbon and, instead of just going out with the exhaust, it lodges itself across the spark plug gap. Carbon conducts electricity and effectively shorts the spark jumping across the gap. - Joe -
@@joesinakandid528 Never thought about that, it makes perfect sense. Those things literally arc weld themselves in place, and seemed unusually tough to break, despite their tiny size. Maybe they're carbon nanotubes! Thanks, Joe!
You are definately a cool mechanic. I've always been of the same mind. If a spark plug has a gap it's close enough. I run Fram filters in my truck too..No problem in over 50 years. Thanks Steve!
Fram filters are the worst out there according to extensive testing,napa gold was rated one of the highest if not the highest,fram least amount of paper filtering element,bottom of the barrel
As a kid, we used to mix gas with used engine oil to run our two-stroke dirt bikes and go cart. Used to have to check the plugs often. LOL. I think knee-jerk check the plug comes from the early two strokes fouling plugs.
Retired automotive instructor.... like he mentioned it can lead to damaged components. Electricity will take the path of least resistance... the ignition module and coil will increase spark output in order to jump a wide gap... this can lead to premature ignition coil damage however if you have a bad connection or damaged plug wire insulation most ofter it will cause the spark to jump to ground before it reaches the spark plug... you can also read the increased kv voltage on an oscilloscope.. if an engine is burning a little oil you can open the plug gap up which will increase spark voltage and may help keep the plug from oil fouling... only recommend on an old worn engine....
If everything else is right, then the plug gap is just a suggestion. However, a weak coil will rear its ugly head if the gap is too much. Likewise, if the motor is using oil, a small gap will foul more easily. I have some old outboards dating from the 1920's through the 1950's. The factory spec on oil ratio is 1/2 pint of oil per gallon of gas. One goes so far as to require 1 full pintg per gallon-yes, an 8 to 1 ratio. Somehow, I don't think these motors would run very long with plugs gapped at .010
I would like to see these tested under a load (i.e. some tall grass) to see if there are performance issues with either one. I may try this experiment too.
Good video. However, I've been pulling, cleaning, and re-gapping my plugs for nearly 50 years without a problem, so I think I'll continue. In doing so, my plugs seem to last about 25 years.
@@mikespain8655 I'll posit that replacing a spark plug for only a few dollars is well worth it to eliminate the possibility that there are minor issues with the plug that sap performance and increase emissions. A thermal stress crack in the porcelain, conductor, and/or suppression resistor can form from the extreme thermal cycling that a plug sees. It's possible that there's a well-formed tracking pathway or a few small pathways that developed over time which can't be fixed and will always partially (sometimes completely) divert electrical energy away from the electrodes. That reason also justifies regular replacement of spark plug wires or coil pack boots because tracking burns/melts them and the track can never be fixed. It's possible that there's internal corrosion which increases the resistance of the plug's guts themselves. It's quite often that a plug has a ring of rust around the place where the porcelain meets the metal body. As the plug wears, all of the sharp corona discharge points wear away because the spark jumps from the highest and closest one first until that place has been vaporized, and it carries on until the surfaces of both electrodes are rounded and polished smooth. This is undesirable because the spark forms easiest and it is most efficient maintaining the ionized arc when those sharp corona points are present and utilized. That is why platinum and iridium plugs have a very tiny, sharp needle point for both electrodes as well as using the very arc erosion resistant platinum and iridium metals. Those plugs maintain a pointy, hard tip/edge which presents a fantastic corona breakout point for the spark to jump across and stay concentrated and very hot during the full duration of the coil's magnetic field collapse. In a combustion chamber at TDC compression, the air is much more dense than air at atmospheric pressure and it's more difficult to form a spark. You can actually see this by using a scope to plot the primary and secondary waveforms. The strike voltage peak will be higher. Having that sharp corona breakout electrode is much better than a rounded arc-polished electrode surface even if the latter is gapped correctly again. A poor electrode form will cause spark to be delayed in timing and it'll be wimpy, which affects power and emissions. Most new cars today are equipped with iridium or platinum plugs, and they are long service life plugs due to their wear resistance. My Toyota for example, calls for NGK Laser Iridium plugs at a 120k mile lifetime. I changed them at 60k. Why? The 4 of them were $40 from the dealer and I always do perpetual maintenance that preserves the efficiency of combustion as well as reducing the amount of engine oil burned in order to prolong the life of the catalytic converter which is a big expense that plagues older cars. The dreaded P0420. 🙀 $40 in nice new plugs was worth it to make sure the fuel:air charge is ignited as best as possible just like when the engine was brand new. This also involves MAF sensor cleaning, throttle body cleaning, fuel injector cleaning or replacement, AFR and O2 sensor replacement, thermostat replacement, and the use of quality gasoline. Most of that doesn't apply to a lawn mower engine of course. In fact, most of this won't apply to a flathead mower engine except when tracking or corrosion gets really bad and causes misfires, or decreases power and fuel economy enough to be noticeable. I just want to offer up reasons why "good" plugs being thrown away aren't always "good" despite appearing to be in one piece, and that being penny wise but pound foolish is not a very good strategy when maintaining a piece of very expensive machinery.
Most people are very quick to change the spark plug if the machine is even slightly difficult to start. The problem is more likely to be caused by something else such as stale gas, or a blocked spark arrester. A genuinely bad spark plug is rarely if ever the problem. If the plug is sooty, it's easy to clean. I find spark plugs don't often need replacing and last for years. I can't really see the point of the video, as it's so easy to set the correct gap with a feeler gauge or an accurately measured piece of card, and having a gap which is much too small or too big is asking for problems somewhere along the line.
@@mannys9130 That's pretty interesting stuff, but pretty useless in a real life troubleshooting. I just ground the plug against the engine and crank. If I see spark it's fine. Personally I think It's a waste to replace something that works fine. If it's working it ain't broke. Guess that's what comes from me being a country guy, on the farm you just gotta simply make things go XD
Small engines yes... EFI with a system that adjust fueling and timing based on gap, air etc Just replaced my plug in my truck. .040 gap is what it requires, it came out at 0.0625... lean popping and running hot. Not lean enough the melt a piston or burn a valve... thanks to the EFI and the O2 sensors which was reading "lean" and throwing fuel at it like bailing water out of a sinking ship. I'll let you know what the next full tank gives me for Milage increase from the 13mpg
I had a 7 HP Briggs & Stratton . The gas was in over the winter . I flushed the tank , line , removed and cleaned the carb . I put in all new gas . I cleaned the plug, it was not wet with gas . No start . The gap was .025 . I regapped the plug to .030 . It started on the first pull .
It was a coincidence.Truthfully, .005 of an inch will not create a spark/no spark scenario in a small engine. These are not alcohol burning multi-cylinder race engines. Thats what Steve was trying to say and many totally missed his point.
For whatever the reason , that was the last thing I did to get it to run . Again , the plug was not fouled or wet with gas . And I did give it about a dozen pulls with the plug out in case there was fuel in the cylinder .
@@StevesSmallEngineSaloon If your standard for whether or not spark plug gap matters is simply whether an engine will start and run under no load, I think you're a tad goofy.
Good one Steve. I would not have known that until you showed us. I never really worried about having gap perfect. I just usually guess at it I basically make sure gap is reasonable. Just like when I sharpen a blade I never worry to much about the balance. I hang it on nail and if it's fairly level I go with it.
Maybe on a Honda gap doesn't matter.... But I bought a Toro early this season. Trouble with warm engine restart. Gap was almost nonexistent, regapped plug, runs like a jewel now. Took about 12 seconds to fix..... thanks for the video, but I'll keep checking plug gap anyways.
I agree it's not that crucial. Only in a few cases have I seen it matter some. Like in the 1986 Chevy Celebrity I used to have that had early fuel injection on a four cylinder, it called for .060 gap and I was told by someone in the know that the larger gap for for the leaner mixture and he told me that an .030 gap would mean horrible misfires. Also when I was into 2 stroke Honda scooters we found through experience that the Honda spree liked an .025 gap over the .028 or larger. Those things only liked the stock NGK BPR6HS plugs as well, they were very finicky that way. Other than that most stuff doesn't care, just like you showed. I had a late 70s 5 HP Briggs on a rear engine rider that the gap was almost closed and the plug was loose and the thing still mowed 6 foot tall grass with no issues.
i gapped a weedwacker plug to spec and it felt ok but would just eat through a tank of gas then i tried a gap that you said then it seemed to have more power and it was more fuel efficient
And for 50 years I have painstakingly checked the specs for spark plug gap and set them accordingly. Thanks Steve for letting me know I’ve wasted quite a few hours of my life doing something unnecessarily👍🏻
@@KensSmallEngineRepair Coil gap does nothing, I have gapped engines coils and some I intentionally gapped wrong, It runs the same all round. I did this with Honda's, Briggs, Tecumseh, Onan, Robin, and many more, It does not matter.
@@AJRestoration He is right that it will change the base ignition timing, however that wont stop the engine from running, it just wont have quite as much power. The coil low tension is charged faster the smaller the gap, just as it charged faster as RPM rises which results spark timing advancing as RPM rises, it does that by design. When the module senses the coil is fully charged it opens the circuit and coil HT sparks. So the smaller the air gap is the more advanced the base timing is. If you set it too wide it will just retard the ignition base timing a bit and so spark will be a bit late and thus you loose some power. Would it be enough to notice it ?, maybe not.
Saw this video and needed to so some weed whacking. It was sputtering a tad and not the same power I was accustom to. Boom what a difference a fresh plug makes on an old machine. Once again I have followed the same over wintering routines that Steve has recommended over the years. Mainly storing with fresh gas and starting at least once a month. Cold damp spring in Oregon this year, yet the yard equip. still humming along. Thanks Steve, my stuff is old from the early 2000's, still doing the job.
LOL your stuff is old....early 2000's. I am running mostly small engines from the early 1960's. I do have some new stuff though. Generator, snowblower, and cheap line trimmer is newish. My Yard Machines line trimmer is crap, I should never have even consider buying this. Thought the price was right for a straight shaft trimmer with clutch. Fixed up a friends trimmer the other day, smallest of Stihl curved shaft trimmers, and very hard used. WAY better, way more power, way less pulling binding grass out of the cracks; and I now see the price is about the same as what I paid for what appeared to be a higher end type machine. I don't think I can even replace the trimmer head with a better one. Damn thing is head on by a friction/jam washer. Some of the older stuff was made way better, but there is some decent manufactures of small engine equipment today too.... I will never buy anything from Yard Machines again though. My trimmer has only a few hours on it. Only changed the line once. I will junk this before spending any money fixing/replacing parts, and I can tell it will not last. I have an old Homelite line trimmer someone gave me several years ago, that I haven't gotten around to rebuilding the carb, replacing the primer bulb and maybe the gas lines and filter as well. Now I am planning to get this running before my crap Yard Machines trimmer falls apart. I bet this old Homelite beats the pants off my new trimmer.
Had carbon build up on my Toro sp and cleaned it by spraying with circuit cleaner. No scrubbing needed. Let air dry about one minute and screwed back in. Started on first pull.
I don’t really ever replace spark plugs anymore. I clean them with my torch, then blow out all the burned up deposits and it works every time. I swear I had a briggs engine from the 1960’s and the plug was original. I heated that baby red hot and after it cooled the plug looked like brand new. No wear on the electrode, installed it and worked perfect.
I have always been told that if you got a misfire in an engine that a lot of times reducing the gap in an emergency if you have no other spark plug around usually fixes it and I’ve actually tried it once and it did work
I have a feeler gauge and the coin shaped gauge. So I have the right equipment. For the last 30 years I have used those tools AND I have on my Ski doos and wheelers and chainsaws and mowers and many outdoor pieces of equipment run into many many situations where i did not have access to those tools and gapped the plugs by eyeball and never had a problem. I bet its been ten years since i gap measured a plug. Long ago after "field" repairing some toy I never went back and remeasured because they have run fine! This seems to be a conspiracy by the gap tool makers to sell a pice of equipent that modern engines do not even care about any longer. One adjust ment to the next when I have gap tested them has never seemed to make any difference, Thanks for confiriming my suspicions Steve! Good work.
If only I had a dollar for every customer that said it only needs a spark plug Thanks for the entertainment Steve Cheers Chris at cutting edge Australia
@@StevesSmallEngineSaloon Cheers Steve we say "crack one for me" in Australia meaning enjoy a beer for me when you are not able to be there to enjoy one with you keep up the great work and crack one for me tnx mate
Good video Steve! I agree with your points. I have never seen anyone start or experienced myself starting a neglected engine and worried about the spark gap, short of extreme fouling or damage. If it sparks it will ignite!
That was pretty funny. Anyone with a race car that has a big coil knows that the gap you started the 1/4 with was a LOT tighter than the one you brought back to the trailer.... with the car still running strong.
So I was just talking about plugs today. I was trying to.find out why it is important to use the "correct" I normally just Find a new one that looks like it and I have not had a problom yet. What can happen not using what th we oem recommend? Thanks so much for your chanel. I have learned a ton from you and fix things I normally get for free. Im getting pretty confident in my work for the most part, and what to look for because of you
Hey Steve I have a old tiller that has been sitting for about a decade. I got the flywheel loose but when I turn it I think it’s hitting something and preventing it from moving any further. I moved it backwards and the valves move but it stops at the same point. I don’t know what’s going on. Do you think you might have a solution?
His POINT IS that "if your engine won't start, it is not the spark plug gap". I do not think he is advising to change the gap on your plug, but if you are diagnosing a mower that will not start, then (on a healthy plug) it is not the gap.
I read that the gap also effects the timing, and this made sense to me as an electronics tech, but perhaps today, without points and condensers, this is not so much the case??? How does this make sense? Well there needs to be enough voltage to jump the gap, and I read that this voltage builds up till it makes the jump. This happens very very quickly. The idea here is that with a small gap the spark happens earlier and at a lower voltage, where as with a large gap, the spark happens later and at a higher voltage. Granted this happens really fast, and maybe with a lawnmower it doesn't make a noticeable difference??? I am no expert though; self taught mostly. Also if your spark is weak it may not have the voltage to make the jump over a large gap. You know how mechanics lay their spark plugs onto a metal part of the engine, to see if there is any spark. I read years ago that the spark behaves differently under pressure and with the gas injected, when installed; compared with sparking outside of the engine. If you have a weak spark, it may look ok outside of the engine, but not work well or at all when installed. This is where a spark tester shines...or with enough experience, one can tell by the brightness and sound, outside of the engine, if it has a strong spark. I made a tester out of a spark plug that I removed the ground adjustable electrode from. The gap can't get much bigger ;-) I soldered a ground wire with alligator clip to the body of plug so I can be certain the plug is well grounded. If I get a good spark with this plug, outside of the engine, I can be sure it has a decent spark inside the engine too. Perhaps the gap is not "critical" to getting the engine running, but it is important.
I have had experience with the gap being too large. Sure it starts and runs but I have seen it where the engine will quit after running it under load for rather short periods of time. Always gap your plugs properly!
All these comments. Did you listen 2:19 ? Damaged vs running are two separate things. A gap isn't going to fix a dead mower. Unless your coil is also buggered. In which case close it down but have the .028 isn't super critical.
Very informative channel, glad I found ya Just replaced the exhaust lifter that was cracked on my gcv pressure washer 190 and now pull starts easy. My issue is it pulsating at idle and even though it seems to spray well it will backfire like once in a while. Do they pulsate at idle? I have noticed that at times it looses water pressure but my other one did too but as this one does if you let up on the trigger and press again and pressure comes back Sorry for dragging this out, my main concern is the idle pulsating issue, thanks
Hay steve i have a motor off a snowblower 5hp tecumseh points look brand new yes had them off there clean and gaped no spark how do i test points and the coil to see if any good and how do set coil on those in side flywheel ? Thanks
this was a surprise. i dropped a plug not to long ago and the gap closed to around 10 and i didnt notice. it made the engine hunt and after recleaning the carb and changing governor springs i said well that new plug must be bad and there it was almost tuching so i just pulled it apart so it looked good and it ran perfect.
I think years back with lower output ignition systems plug gap was much more important , I have seen engines refuse to fire with to wide a gap .but that's little Briggs made in the forties or fifties . To give Steve credit he did say Honda , and they have about the best small engine ignition on the market
I tore some plugs out of my subaru that were so worn there was barely anything left to it. Still ran, not great, but it ran. Didn't think twice about checking gap on the new plugs since I'd seen the 1/4 inch gap I was running on before
A lot of spark plugs are pre-gapped. Copper ones need to be gapped, but the platinum and iridium sometimes come with a protective sleeve on them. It's used to ensure the gap remains consistent after it leaves the factory. Usually because, there is a puck of metal on the tip of the electrode. And improper gapping techniques can chip off the puck, compromising performance and life span of the plug.
Yeh, and clarify that they're not testing spark plugs: they're testing the ignition system up to but not including the spark plug... I think! At least I'd like that to be clarified for me! Thanks Steve, from France.
Good point John. I should have expanded on your note as well as I often check for spark by grounding the ignition lead with a tester. I found the automotive type dont work that well for two stroke engines.
STEVE, say it ain’t so!! I believe today I proved this wrong with 2 stoke engines today. It would start then stall when cold, then wouldn’t start… found the gap to be .10 thousands, open up the gap and it started cold and hot
You can widen the gap if you have a high performance coil/coils on a car/truck engine. I went from .044 to .050 on my 2013 Scion TC with Accel Super Coil Packs and it seems to run smoother and better. It pulls a bit stronger too. Probably because there is more voltage from the coils providing a bigger spark. Does that sound about right?
Hi Steve question: I have a ryobi 2 cycle switchable tool used for gardening. A trimmer and weed wacker two attachments. Had it for a year and a half. Problem is the clattering sound. Sound is coming from back end of the tool opposite the attachment end. What’s going on?
I agree about the gap won't prevent the engine from starting, but what about the other variables. Gas mileage, engine cooling efficiency, and pollution. A finely tuned engine will give you better gas mileage, an engine that's running at proper temperature and minimizing pollution. I imagine there are other issues as well.
Steve you proved you point, now I had nothing better to do so I wanted to check my 2016 Accent`s spark plugs Believe or not I could not find it in the owner`s manual what should the gap be? what you think the gap was about .037" so I left the way it was.
Thanks for the videos, because I was sweating it. I have a engine in a vehicle that has no paperwork or information and the plugs are shot. So I guess I'll do better 30 and 45? It's a older 302 fuel injection engine in a Jeep . It's a custom build With no documentation .
Cheers again from Calgary Steve! I have been telling customers and friends alike this for years. Funny how few believe me and instead buy into the BS. But seriously man, Lucky Lager? More like Yucky Lager, lol!
Dude, love your channel. Im in BC too (east kootenays) and finding a deceny small engine repair guy is a crap shoot. Youve put me on the right path more than once. Cheers, bud.
So from your little test and what you are saying, it sounds to me like if you’re engine is not starting correctly, it may not be from your gap being off, but it just may be from damage, that you mentioned, done by running it with the gap being off.
Steve, I’m sure this question is asked a lot. How often should we be changing spark plugs on small engines, both 2 and 4 cycle? And what are some signs that it should be changed? Thanks!
If its dead, change it, if it works leave it. This is one of those things you can clean and reuse for YEARS. If it ain't broke, don't replace it. You are wasting your money.
Agreed, the gap won't cause an engine not to run at all. If you pull out the plug and find an excessively large worn gap, the no start may be related to the ignition coil which likely has an internal short due to the high voltage that the secondary was forced to produce in order to strike that arc each revolution (wasted spark). 😸 When examining ignition coil primary and secondary coil waveforms, the strike peak will be much larger before the arc forms and the higher voltage is more likely to burn through insulation and cause a short. An excessive gap COULD encourage tracking from the plug's outer electrode tip down to the metal body of the plug or across the dirty plug boot surface to the head. That's because it's easier to jump through that track rather than jump the excessive gap in a cylinder of air and fuel that has a 7:1 to 10:1 compression ratio. If the carb on the engine is a bit dirty and she runs a lil on the lean side, that makes this slightly more likely to happen than the same engine running near stoichiometrically or rich. Overall though, great demo Steve. The engine will run like crap with an out of spec gap, but running is running regardless. Unless the ground strap broke off or is bridged entirely, it'll spark when the plug's guts and coil and wire are all in proper shape. 👍 Hard evidence and experimentation is *ALWAYS* appreciated and valuable. We can posit and hypothesize all day long, but until someone says "I have evidence supporting my claim" we don't have cause to believe one or the other. I like evidence. 😎👍
Combustible compressed air/fuel doesn’t know if it’s ignited by a spark, Bic lighter or military grade laser. It just goes “bang”. What the gap determines is how much voltage is required to jump across the gap and create a spark. If the gap is too small, the spark will be weak and might not ignite the air/fuel mixture correctly. On the other hand, if the gap is too large, the spark will be too strong and can cause damage to the engine. A large spark plug gap setting requires a higher voltage to jump the distance between the electrodes. This is because there is a higher voltage build-up in the ignition system prior to spark discharge. At least this is what the automotive technical schools teach.
Running a wide gap shortens the life of the coil, plug wire, points or module. The higher the dynamic compression the smaller the gap has to be to prevent misfires for a given ignition system.
Steve, I respectfully disagree for the first time. A few years ago when I was just getting into this as a hobby I got bit in the ass by a new spark plug. The Briggs on a mower wouldn’t start. The owner said he couldn’t start it so he changed the plug and still it wouldn’t start. I checked the carb, the flywheel key, gapped and sanded the coil, checked the resistance on the coil and in the end it was the new plug with a gap of .070. Gapped the plug to .030 and problem solved. Lesson learned. I now check the gap every time. Cheers
@@giggiddy It was a Canadian Tire brand. Either First Fire or Autolite. However, since then I’ve seen many new plugs from well known brands that were not gapped correctly.
A small gap might make up for a weak coil... but you still have a weak coil that will make the engine harder to start. That wider gap may actually cause early coil failure with newer electronic ignitions because the voltage builds higher before jumping the gap. In a nutshell, the gap isn't critical to how the engine runs but it's best to be in the ballpark for longevity of all systems. It will also give you an idea of how worn the plug is over time if you always use the same base gap when new.
I find passing the wire gauge through the gap can clear the surfaces to allow the spark to occur and where it is designed to occur. Plugs last a very long time following spec and using a wire gauge. You get a look at what is left behind for evidence of life in that combustion chamber. If it fouled, you see the cause there.
I’ll start with I don’t know what l’m talking about. The gap determines the exposure of the fuel mixture to an ignition source therefore the flame pattern that results. The resulting power band and emissions profile should be affected. I saw a comment about trying these experiments under load conditions to check for power loss.
A huge unnecessary gap does only one thing , it overload the ignition system . when you measure a correctly gaped plug firing voltage you get 7 to 9 kilo volts . with that huge gap plug , probably 25 to 30 kv . You accomplish nothing with that huge gap . Just follow the recommended gap .
Well I don’t know ! I have had several strimmers that were as touchy AF about plug gap. This does NOT apply to cars and vans, where you can feel the difference even it the only thing you have done is to check the plug gaps.
I had a push mower (30" Toro Timecutter) that came through my shop and ut was popping when it warmed up. Took out spark plug and found it very close to .10 gap. I made it .30 and the popping stopped. I'm guessing it was caused by a misfire.
Well Steve, I've just found a video that solidly disagrees with your own experiment and conclusion here. Very interesting! This engine in this video DOES NOT RUN at all with an excessive gap, and it did run fine after the gap was corrected. The spark plug gap was the sole cause for the no-start problem with this generator engine. After the gap was fixed, it ran great with ether and after the carb was repaired and reinstalled it ran great on its own. It would appear that unfortunately yes, a gap that is too large WILL sometimes cause an engine to not run. Must be a case by case thing. I'm so shocked (pun intended) that your lawn mower ran but this generator would not. Take a look. This is not an angry post. No hate meant toward you. I'm merely sharing information so we can learn. :) 5:50 The engine doesn't run as-is with ether sprayed into the intake. 7:30 The coil is properly sparking a test lamp so there is some output. 8:03 Trying again, plug properly installed and connected as-is. No firing with ether this time either. 9:05 The plug clearly has continuity because it has a strong spark but only at 1atm of air density. 11:12 The coil core legs and flywheel magnet are definitely properly timed. 14:12 The gap is found to be huge at over .055" 14:58 re-gapped to around .035" and reinstalled. 15:32 It now starts correctly with ether! 35:26 Undeniable proof of the coil's strength and proper voltage output with an arc length testing tool. Sometimes RU-vid doesn't like links in comments so I'll reply separately to this comment with the link and I'll just give the details in this one so you can search for the vid if the link is auto-deleted. The video is made by James Condon, and it's called "Trashed Rigid Generator - Will Not Start" The full video is 1:03:28 long, just to be sure you've found the correct one. 👍 Any thoughts?
