OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Honda Engines Yard King 125cc Briggs 450-series which spark plug?

idling a little erratically, also coughs a bit and black smoke whenever I up-throttle sharply, so I decided to check plug...to my surprise my usual spark plug tool did not fit, it's a 5/8 hex plug instead of usual 13/16..ok, no biggie.Get 5/8 plug socket...but...plug is also 19mm reach , ie, equivalent to Champion N9YC or NGK BP7ES in reach for example..which I find odd for any Briggs motor..

Every way you look at it, this plug looks odd for Briggs 4stroke.

Definitely Briggs engine, has several sticker tags on it..looks like some kind of variation of a Quantum engine..even though I know Yard King mowers are NOW Chonda-engines..whih that confusion might be why it could have wrong shape/style plug in it.

.then I look in plug hole...
looks not long enough not enough threads to match that 19mm reach plug..which is bad of course because means last 2-3 threads on plug could get deposits on tjem and jam plug in plughole...
..BUT...BUT..otoh, hole appears TOO long for usual common Briggs spark-plug size..which of course has same reach as a Victa Champion CJ8..whatever reach that is classed as..maybe 1/2 or 5/8?

So I try to look up engine model in online plug catalogues..absolute nightmare . So is trying to get anywhere with it on Briggs&Stratton USA site...these Yard King mowers are non North American market anyway, so this engine series it might not even be listed there at all.

anyone know what it is and what plug it takes?

I have images of ID stickers on engine and front of chassis shell.

Actually I'm now beginning to think these ARE a Chonda with B&S rebadging on them..

Remember it is only a Briggs so any plug that fits will do. They are an OHV motor so that is why the longer plug thread and yes they are Chinese but not a Chonda which is a Honda clone

Do you know what plug-hole reach that is classed as?

I mean, almost any of the dozens of used plugs I have match the hole diameter/thread...but none I have match the thread-reach..

so I don't want unoccupied threads on either hole or plug..

I saw some listed on ebay .Chinese brand such as A7 TC which are listed for scooters and wtf else, but look possibly right reach/thread length..

But I'd prefer not to use Chinese plugs but rather work out an NGK part number for a compatible one..

You are way over thinking this, those motors are a bit on the average scale so any long reach plug you have that works will be fine

well, yeah..those specs match Torch-style one in it..is 5/8 hex X 19mm N9YC length reach...gasket-seat......but that is 2-3 threads deeper than hole...and you can tell looking at old plug, there is an obvious demarcation line on threads...that last 2-3 threads on plug itself were exposed to flame/deposits in chamber. which makes me nervous..goes against very old automotive no-nos.. .lol..

If you're worried about it BH put a couple more spark plug washers on the spark plug.

It's not uncommon for the tolerance specs to be out a little on cheaply made equipment.

RC12YC or BCPR5ES or BKR5ES will all fit and are the correct spec plug for this engine.

For future reference the engine is Briggs 08P502-0037-H1 per the serial number.

this is one in it...I'd assumed it was an error-replacement..but maybe it is the actual OE..

spark plug images are added to OP..

or not..nowhere to now add them, apparently..

Well, waiting for the replacement I ordered which will match the hole depth better I feel, I put in an old NGK I found in my bits and pieces,
, probably 20+ years old lying around, it is 5/8 hex, it is 19mm reach, looks about same centre-electroide heat-range length, but it is some series NGK which has a thin needle-pointed centre electrode.

the one I took out, which may or may not be OE, was ARCHER A941P..

Anyway, thing started 1st pull, ran faultlessly..stutter/cough/miss when sudden throttle-up and black smoke-puff seems gone even.

Makes me reluctant to now try new one I ordered on Temu for $2.90 all-up which is en-route....

The engine would originally came with Champion under Briggs PN 692051 which only indirectly crosses to the Archer A941P plug.

The Briggs PN did however cross to the NGK-2460 (BKR5ES) and the Kohler 25 132 12-S (NGK CS6).

Sounds like someone said to themselves it looks the same so use it.

well the replacement I ordered from TEMU because it had a 1/2" hole reach instead of 19mm just arrived.

I was so excited..

Lucky I was not pinning my hopes on that and found that old NGK I mentioned...because this thing is some series plug with SMALLER DIAMETER HOLE..never even seen one with smaller diameter hole b4..described as suiting many scooters and stuff...hole reach matched what I wanted, centre electrode looked about right length...5/8 hex...I assumed that was all the specs I needed...

never counted on a plughole diameter looks like you could put it in a COX/TAIPAN 2.5cc RC model-airplane engine..

part number AEA-brand , A7TC..

Yes the A7TC is 10mm x 1mm, Thread Range: 12.7mm BriggsHandy

You don't need to worry about the plug length being longer than the hole ,I've had mower spark plugs
last 10 years ,the Briggs motors can look barely used in 7 years and are completely worn out blowing smoke
like the one below ( Oil still looked new) ,I checked a 500E and 550EX and both have the last threads black .

After all they are only cheaply made motors.

yeah, 10mm/.394" wide...particular seller ad I responded to never included a close-up measurements pic as I've now seen with others selling same item.., or I would have spotted the miniature diameter of it..

Probably that item BNIB will sit in shed shelf longer and gathering more dust than the mysterious needle-point used NGK I just reactivated had..

look at what I found in my bits and pieces...Motorcraft, but Made in Japan Motorcraft which is probably NGK or Denso or Hitachi outsource,

AG43CEU11...ND would be my top guess due to U-electrode feature which is old ND gimmick..got several of them maybe a set of 4, whatever they were originally intended for...

5/8 hex...check ..

but look at nose of it..although 19mm reach...last few threads have been machined blank (original) ..so no further concerns re fouled/jammed threads just in case that was ever a risk.

11 in part number indicates 1.1mm gap, which is slightly too wide, but soon adjusted down to correct 0.9mm

Hi BriggsHandy,

The AG43CEU11 was a revised spark plug and is commonly found in Ford 5.4 Litre V8.

Ford has encountered issues with spark plug breakage in several of its V8 engines, particularly the 5.4L engines from the early 2000s, where the spark plugs could become stuck in the cylinder head, leading to the possibility of breaking when attempting removal. To address this issue, Ford made several changes and recommendations:

Combustion temperatures typically range from around 1,370°C to 1,650°C in a 5.4 V8.

Combustion temperatures typically range from around 593°C to 870°C in a Briggs OHV motor.

The higher combustion temperatures can contribute to increased carbon buildup in an engine.

While it's not impossible for a spark plug to seize in a Briggs & Stratton 4-stroke OHV lawn mower engine, it is typically less common due to lower combustion temperatures, proper maintenance, and the engine's design. However, it's still important to regularly check and maintain the spark plug to avoid any potential issues. If a plug does become difficult to remove, using penetrating oil and appropriate tools carefully can help prevent damage to the engine.

Cheers
Max.

[b][/b]The AG43CEU11 was a revised spark plug and is commonly found in Ford 5.4 Litre V8.

thanks for that I was curious...I knew with any Motorcraft/Autolite item it was most likely Ford..is as to Ford as AC/Delco is GM.