Regapped spark plug, now mower starts easier than ever.

[CharlieJ]

I bought a lightly used Toro super recycler lawn mower a few years ago and changed the oil and air filter since they were dirty. The engine is a 190cc OHV. I left the spark plug alone since it started in 2-3 pulls and ran fine.
I took the spark plug out over the weekend to check it since I hadn't ever before. I believe it is the original Champion brand plug. The plug looked OK, slightly rich and a light ash from oil, I cleaned it with a brass bristle brush and checked the gap. I have a wire-type spark plug gauge and the gap of the plug was <. 025 inch! (the smallest measurement wire on the gauge)
I gapped the plug to .045 just to see what happens on the on the extreme opposite side of the gap. (I believe the gap should be .030) And now, the engine starts first pull! It's never done that! And, seems to run the same.
I don't know why the spark plug was <.025, but I am glad I checked it. It seems like the larger gap helped the engine start easier, possibly due to larger spark? So, check your plugs on your small equipment if you haven't done so already!

 

[Urshurak776]

So, I have a Troy-Bilt, Honda Engine mower. Probably 9 years old now, closer to 10. Still using the original plug. I pull it every year, clean it and make sure gap is good, then just roll on......

Oil gets changed every Spring (doing it this weekend) with whatever left over oil I have. I have a 5qt jug that just gets some left over from oil changes. It's typically a mix of 0W-20, 5W-30 or 40. Mix of synthetic and syn blend. Whatever is in there, goes in the mower every year.

The carburetor is giving me some issues last year or so. I bought a cheap junk knockoff Chineseium one to install. Just need it to last this year. The deck is worn out with holes and wheels are falling off. Time for a new one, but going to try and get this one to go one more year......

 

[BigCahuna]

So, I have a Troy-Bilt, Honda Engine mower. Probably 9 years old now, closer to 10. Still using the original plug. I pull it every year, clean it and make sure gap is good, then just roll on......

Oil gets changed every Spring (doing it this weekend) with whatever left over oil I have. I have a 5qt jug that just gets some left over from oil changes. It's typically a mix of 0W-20, 5W-30 or 40. Mix of synthetic and syn blend. Whatever is in there, goes in the mower every year.

The carburetor is giving me some issues last year or so. I bought a cheap junk knockoff Chineseium one to install. Just need it to last this year. The deck is worn out with holes and wheels are falling off. Time for a new one, but going to try and get this one to go one more year......

I run a bottle of carb cleaner in the gas can for my mowers. I feel that does the trick for me as my mowers start easy all the time, and usually first pull in the spring. Plus I never use old gas that's been sitting over the winter in them.,,

 

[Urshurak776]

I run a bottle of carb cleaner in the gas can for my mowers. I feel that does the trick for me as my mowers start easy all the time, and usually first pull in the spring. Plus I never use old gas that's been sitting over the winter in them.,,

Now, I use ethanol free fuel, plus I mix in some carb cleaner also. Worked pretty good for a long time. Just now having issues. I didn't always use ethanol free though.

 

[Wolfshead]

In my Troy Bilt , (B&S 20 HP ) Mower i use Non ethanol gas and a splash of MMO.No problems in 9 years .

 

[Brad_C]

It seems like the larger gap helped the engine start easier, possibly due to larger spark? So, check your plugs on your small equipment if you haven't done so already!

Spark gap is a delicate balance of providing a spark that doesn't blow out versus a spark large enough to provide reliable ignition while matching the coil impedance. Too much gap, high voltage, weak and short spark. Too small gap, low voltage, strong and long spark.

So yes in general the larger the spark the more likely it is to ignite the mix. Go too big and you get a large but weak spark that gets blown out before it can ignite something. Go too small and you get a small but robust spark. It won't blow out, but it also won't extract the maximum power from the coil, and will hide better from the flammable mix.

I know it sounds cliched, but the manufacturer will have designed the ignition with a specific gap range. You'll likely get a lot of advice along the lines of "ethanol, carb cleaner, 10w40, stabil, git-er-done, runs good, fresh gas, OCI, chinese carb, MMO, dugga dugga dugga" but at the end of the day, sticking with the documented gap is likely to provide the most consistent results under a range of operating conditions.

 

[Lubener]

I will try that and see what happens.

 

[CharBaby]

So, I have a Troy-Bilt, Honda Engine mower. Probably 9 years old now, closer to 10. Still using the original plug. I pull it every year, clean it and make sure gap is good, then just roll on......

Oil gets changed every Spring (doing it this weekend) with whatever left over oil I have. I have a 5qt jug that just gets some left over from oil changes. It's typically a mix of 0W-20, 5W-30 or 40. Mix of synthetic and syn blend. Whatever is in there, goes in the mower every year.

The carburetor is giving me some issues last year or so. I bought a cheap junk knockoff Chineseium one to install. Just need it to last this year. The deck is worn out with holes and wheels are falling off. Time for a new one, but going to try and get this one to go one more year......

I have the same/similar Troy-Bill/HONDA mower that I purchased new from Lowe’s in 2009. We’ll be using it this summer for its 17th season and it’s still on the OE NGK plug. Starts first pull all season. Oil is changed each season and uses next to nothing during the season. I have the same carb from the factory and have done nothing to it as of yet. I have however changed the deck as the original had rotted and I had a perfect Craftsman deck(with a fussy B&S engine) as the donor deck.

 

[Urshurak776]

I have the same/similar Troy-Bill/HONDA mower that I purchased new from Lowe’s in 2009. We’ll be using it this summer for its 17th season and it’s still on the OE NGK plug. Starts first pull all season. Oil is changed each season and uses next to nothing during the season. I have the same carb from the factory and have done nothing to it as of yet. I have however changed the deck as the original had rotted and I had a perfect Craftsman deck(with a fussy B&S engine) as the donor deck.

Nice! Great mower. Only issues, as you said, the deck has rotted out. Wheels a little "wobbly" now also. Carb was my fault as I used ethanol gas in it for a couple years before switching to non ethanol. Overall I can't complain. My wife was at Lowes in 2014/2015 time frame and it was on clearance (probably left over.) She called me and I drive down there and grabbed it. Wish I could buy another one!

 

[ka9mnx]

In all my OPE, a non-vented five gallon gas can, non ethanol gas and the right mixture of TCW3 and Seafoam. Everything starts right up with stock spark plug gaps. Engines run strong with no oil consumption. Gas seems to last forever.

 

[barryh]

I know it sounds cliched, but the manufacturer will have designed the ignition with a specific gap range.

You would think so, but I wonder.

I have a 1979 BMW motorcycle with point ignition and a recommended park plug gap of 0.25" so real old school.

When BMW introduced electronic ignition in 1981 they halved the primary resistance of the coil which should have increased spark energy by getting on 4 fold (spark energy = 1/2 the inductance times the primary current squared) and yet they kept the plug gap at 0.025" That makes no sense to me as keeping the gap small prevents the electronic ignition from performing any better than the points ignition other than it achieves a bigger safety margin against misfires.

In practice even the points ignition seems happy with a 0.28" or 0.030" gap and given spark power is directly proportional to the square of arc-over voltage then even modest increases in gap will be beneficial.

 

[CharBaby]

Nice! Great mower. Only issues, as you said, the deck has rotted out. Wheels a little "wobbly" now also. Carb was my fault as I used ethanol gas in it for a couple years before switching to non ethanol. Overall I can't complain. My wife was at Lowes in 2014/2015 time frame and it was on clearance (probably left over.) She called me and I drive down there and grabbed it. Wish I could buy another one!

I have only used E10 gas in this Honda engine that I speak of. ATMOF, E10 is all that I use in everything since it has been in my area probably about the late 90’s.
I’m not an advocate for ethanol gas, give me the good stuff! However, I can’t say that I’ve ever had any issues with E10 in anything, lawnmowers, snowblowers, leaf blowers, trimmers, old carb’s cars, nor anything new. But I do know of those who have had issues.

 

[dvblanch]

Non vented cans can be dangerous if they get to hot and build pressure. Few years ago I opened my
shed door on a 95 degree day and one of my plastic cans looked like a balloon. I have since added the push in vents to all my cans and leave them open. Should not cause any problem with EO fuel anyways.

 

[CharBaby]

I may start using E0/non ethanol gas for my small engines.
I have found 2 gas stations that sell E0/non ethanol gas that are not too far of a drive for me. And since I will only visit these stations for filling my gas cans(a couple of times a year), it shouldn't even be a problem.

I will not go out of my way to fill my vehicles each week with E0/non ethanol, which is about $2 more per gallon and a higher octane(~90-91 octane) than my cars require or need. At the gas stations that I frequent most (Exxon/Mobil, SpeedWay, Sunoco etc.), PREMIUM fuel(~91-93 octane) is about $1 more per gallon but are all E10. I only use 87 octane for my vehicle.

I have however used PREMIUM for several tanks of gas for a test/measurement to see if I can get better MPG or noticeable performance(throttle response) and I just don't see/notice a thing. And if I do notice any better throttle response, it isn't worth the $15-$20(vehicle dependent) per full up. EVERY FILL UP! Mostly worst MPG and a lighter wallet.

 

[RazorsEdge]

On the subject of 'spark plug gap'

I installed an new iridium plug without checking what the gap was in our Craftsman last summer. No issues

 

[tbm5690]

The factory gapped Champion that came in the Briggs 223 on my Timemaster was the same story...engine always ran slightly rough at idle and took two pulls on the rope to start. When I replaced it with an NKG and widened the gap the idle smoothed out and now it starts with one pull. Never assume they are gapped the way they should be.

 

[nbpt100]

I always check the gap on a new spark plug. They usually come in at .030. Some of the ready start Briggs Quantum Engines spec a gap of .020. This was to help with starting. But I have used a .030 gap and they often will start with in 2 pulls. I have at times compromised and set the gap to .025.