How To Read Sparkplugs | AFR

How to perform a plug chop and accurately read afr(air/fuel ratio) from a sparkplug - a necessity when tuning two stroke engines.
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[@ludditeneaderthal]

Finally, a good plug chop tutorial! Insulator color reading can get you close (if you use clean plugs each time, each throttle quadrant), but a chop is needed for getting it "on the money". It's ok to use cheap plugs for the color reading runs, but chops MUST use the plugs you plan to run "full time" to be truly accurate. Always informative AND entertaining Alex!

[@2STROKESTUFFING]

Thanks man!

[@DeBoswachter]

I didnt know this one, amazingly usefull since i was struggeling to fine tune my scooter for all throttle positions! Thanks!

[@big_mike_nyc]

I thought the glass of whiskey was to compare the plug color too 😎 🥃 Also when you kill the motor you want to pull and hold the clutch so when you coast to a stop it’s not under load..

[@2STROKESTUFFING]

True, forgot to mention the clutch...

[@mkruk2]

I really appreciate this video. I heard a lot of talk about "plug chopping" on forums but no one really explained how/why. Now I just need to find a stretch of road to go WOT...

[@calamity075]

Needed this. Watched your videos since last year and now getting into the older ones. Just installed a 70cc kit on my bike and it doesn't run quite properly yet (idle sucks ass tbh). Your shit really helps. Thanks my man.

[@joelakata48]

Just found all your amazing in depth videos, thanks for sharing.

[@2STROKESTUFFING]

Thanks man!

[@TheVegasbud]

That was a OLD School tip man ! Your right about the oil ratio type of oil and type of fuel used makes difference in the width of the band insulator Nice Video ..

[@2STROKESTUFFING]

Thanks!

[@icelandicweirdo]

well, while it is correct that the color of the insulator doesnt tell you alot, it does give you an idea of what the engine is doing.... but if you know what your doing, you only use it to determine the mixture at wide open throttle. the rest should be done by feel and ear, at least on a 2 stroke. a rev gauge and temperature gauge are quite nice to have also....... but the whole color thing also depends on what sparkplug is used, the temperature, the moisture level, quality of gas and oil... i mean there are so many variables, i think it is a waste of time and money disecting sparkplugs like that, to me seeing the color of the insulator at the top, is good enough to see if youre in the ballpark, then you can finetune it from there....

[@sciewter]

I agree, get it close and tweak, by the time you are done messing around conditions change and you start over.

[@jasonpearson4983]

@@sciewter that's why......Lectron

[@scottmalcolmson4584]

Just got my first 2 stoke (71 garelli gulp) great vid, also it would be a great day to drink whiskey and talk 2 strokes with this gentleman

[@tonyvargfrost400]

Hmmm... Maybe a small warning! Unscrewing the plug from a hot aluminium-head may destroy the threads. Been there, done that. 😉 Anyways, keep up the good work!

[@2STROKESTUFFING]

Thanks for the warning!

[@ludditeneaderthal]

You unscrew your "warmup" plug a quarter turn cold. Then warm it up, pull hot plug, chop plug is not torqued, just finger tight. You then pull it as soon as the roll stops. Anti seize on the warm up plug threads is a good idea too. Same warm up as a compression test in aluminum parts. So long as you don't torque the cold plug into a hot head, risk is very low. The downside is once your 4 chop runs are done, you have to wait for the engine to be cold to put a "running" plug in under proper torque, because torqueing a cold plug into a hot head will pactically guarantee some head thread comes out next time that plug does, no matter temp.

[@diesmokeyaight6396]

I love this video style still a lot of information but like a small film. keep up the good work. You have my support. Greetz from a 2 stroke lover

[@2STROKESTUFFING]

Thanks man!

[@Hollaendaren]

Good info! And the music was awesome :)

[@2STROKESTUFFING]

Thanks!

[@xibidit]

wow did not know this thank you very much!

[@moto-rambler]

Great video -- thx for sharing.

[@stephenfrancisvoros382]

Cool, at the moment I'm playing with the float level in my Yamaha AG100 1973 A model, mikuni VM20SH carbi, getting my mixture right after fitting new carbi kit, the service manual says to take fuel bowl off, turn carbi upside with gasket removed and not putting any pressure on the needle spring, then measure, the measurement from what is then the highest point of float down to the gasket surface is 19.2, with 2.5mm tolerance, giving you either richer or leaner float level, I'll have to buy a couple more plugs and test it like so, great post once again 👏👏👏

[@arthurdombroskie3083]

Very good information.

[@billbry]

My NASCAR Pro Stock plug readings were the same way, but we used a Jewelers Spectacle to look down in.

[@ghettobikelife8833]

Would temperature have an effect on the soot ring ie. making it thinner? I’ve noticed I can make a rich, black plug go grey by overheating the bike

[@theuniman500]

damn this was so sick to learn thanks

[@outbackenduro7418]

Hi you are a very cool, great presentation no BS !

[@2STROKESTUFFING]

Thanks!

[@Bubba.Braap57]

So if i try the chop test at 1/8 -1/4 throttle for the pilot if should see the 2mm soot ring if the pilot is good?

[@wallereportersurcheminsdet1951]

Incredible . Tanks.

[@nerdhoolio]

Damn your vidz get better and better

[@2STROKESTUFFING]

Thanks!

[@alltheboost5363]

Does this apply to all gas engines (like 4 stroke turbo engine)? Especially the thickness of the black ring?

[@davidchapman3563]

Imma try this this week alex.ill letu kno how it goes bud

[@mbsgarage]

I like watching a Cowboy drama, with gun action.... good job fellas😎

[@benhawke7231]

They make an air/fuel tuning sparkplug that has a see through window that let's you see the color of flame to determine the rich/lean conditions of your combustion. You then can adjust your a/f mixture while the engine is running. I love it. You get a perfect tune every time.

[@2STROKESTUFFING]

I remember seeing one of those in an old magazine, would be interesting to try.

[@benhawke7231]

2STROKE STUFFING I seen a KZbin vid on "For The Bold". He uses it on his Suzuki 550 project. He has a link in the description. I bought one and am willing to put my life on the line for it. It's the easiest way to tune your a/f mixture. Because you tune it while it's running. It's best to have a buddy running the throttle for you for top end adjustments of the carb. And your lean top end with bigger carb issue. To much airflow per displacement. Make a small hole with your lips and suck in as fast as you can, then open your mouth all the way and suck in. You can feel the difference of speed of airflow over the tongue. You have to have a airflow that coincides with the specific gravity of the fuel you're trying to lift up the jets. Just think.. If you put a Holly four barrel carb on that engine, would there be enough vacuum to suck the fuel into the engine?? You have to have the right cfm of card to match the cc and a/f tuning of the cylinder/'s.

[@2STROKESTUFFING]

Thanks, I'll check it out! You're probably right about the carb, I'll have to do some more testing with it tho, before I write it off as too big.

[@frankierutherford1888]

Great job. Any other tips on reading spark plugs would be greatly appreciated my friend.

[@2STROKESTUFFING]

Thanks! Might do a follow up when spring comes and I can include actual runs.

[@conniekahl8015]

Superb!

[@naveedaka]

awesome video

[@2STROKESTUFFING]

Thanks!

[@hopsgarage5513]

Awesome stuff

[@2STROKESTUFFING]

Thanks!

[@pakoaheka1569]

One question about gaping the new plug.I curently using NGK BR9ES with standart gap 0.8mm but for my scooter is reccomended 0.4mm gap with Champion RN1c wich can't get any more.Do i need set the gap to spec of the moped or the spec of the spark data? I have problem with fouling spark's but i don't know why.I drive a lot on 1/2 throttle is that the missing part? Tha ks for answering.

[@derekhall7047]

I love this guy .What's next? Full length movies. So much drama. You must go thru a lot of plugs, sawing off the threads to get a proper chop. I have been doing it wrong.

[@2STROKESTUFFING]

Thanks!

[@alltheboost5363]

Ty good to know

[@AxelP33]

Can you make a video on Timing spark plug read ? Or do you tune by MBT ? Advance past max tq point on dyno then backoff to where it was making the more TQ ?

[@simonekjachnik6634]

can a sparkplug look dark on the outside but still run to lean? my yz250 acting rich on low rmps but when im reving , the motor gets hot and smells like pistonrings..

[@hamishanderson8619]

Aside from the soot ring - the colour of the insulator also indicates what temperatures the cylinder has been experiencing. Yellow to green tinge indicates the engine is running too lean and therefore too hot due to lack of cooling by the fuel mixture. Used to see quite a few post rally engines that had failed due to revving and doughnuts, usually the customer would claim ignorance to any horseplay but the plugs would give them away every time!!

[@nerfinator03]

Please do one on cheap cht's or exhaust temperature gauges.

[@lobotomyy]

*As 15year old i dont have alot of money but what i did is run at full throttle and then just turn engine off and pull plug, but instead off destroying my sparkplug i just check the electrode colour. NGK also used to have a manual back in the days how to read a plug, and i said you should read the electrode not the insulator. Also this is thee first time i heard that you should check the insulator instead of the electrode*

[@jbj198840]

On my 2003 CR125R I run the stock BR9EG..for sake of saving a few dollars can I buy some BR9ES to do some plug chop tests or will it not read the same as the EG?

[@upsidedowndog1256]

Good video. Does the nitro mixture do the same? How fast can your hat go? That looked like 100mph.

[@2STROKESTUFFING]

Thanks! Methanol/nitro is best read by how much of the plug tip plating is being oxidized - 90% is pretty safe.

[@ludditeneaderthal]

He buys z-rated hats, they're quite popular in Norway, especially among 2 stroke skoot fans

[@upsidedowndog1256]

ludditeneaderthal Just don't look up?

[@ludditeneaderthal]

upside downdog well, down in your case... Lol

[@upsidedowndog1256]

ludditeneaderthal THAT'S GREAT! I am smiling big enough to crack a jaw!

[@Dropsix]

Does this work for very slow speeds? Like single track? Or only wide open?

[@joenels4356]

thank you

[@maxprophet2401]

My plug says the last guy only had a pair of pliers. I assume it was tightened with the pliers (or hammer and chisel) because of the marks on the left side of 2 of the hex flats.

[@sciewter]

So what you have is a full on race engine lol.

[@maxprophet2401]

Found the previous owner

[@williamwilliams8145]

In the UK we have a tool called a Gunson Colortune, Which is basically a spark plug with a glass insulator allowing you to see the flame in the combustion chamber and tune it buy the flame colour. Yellow = Rich Light blue = lean Dark blue = OK The down side of this tool is you look at the flame through a tube and can only do so while the bike is stationary (unloaded), However it wouldn't be to hard to attach a small cheap bluetooth camera to the tube, link it with a phone secured on your bike and get your under load readings that way. And because it is made of metal and glass it won't be affected by the oil content of a 2 stroke, and when done you can use the camera as a bike cam. kzbin.info/www/bejne/j2rXaYuee9F-mM0

[@2STROKESTUFFING]

I'll have to get ahold of one of those!

[@shmuck66]

Just a caution. The gunson colour tune can't be used under full load. at least the manufacturer claims. Another down side is there is so much volume in the glass spark plug they give you that it affects compression ratio AND scavenging. so FYI. This is the exact reason I started switching to very very low open volume or exposed volume plugs. less trapped exhaust gasses = less misfire and less chance of deto.

[@johupp]

I just learned of the colortune yesterday. I placed an order this morning and I can't wait until it comes in.

[@240sxxxvids]

Thank you William, I had never heard of this before, just placed my order on eBay! Surprisingly cheap shipping from UK to US. Will take the guess work out of tuning!

[@divinewind131]

Does the milimeter range apply on all 2 strokes (cc's), spark plug types, etc? And is there any different way to tell if the mixture is good without buying a whole bunch of spark plugs? Thanks in advance.

[@1pelikone]

You can do it by ear and feel if you don't need 100% perfect results. Bogging when you give full gas from idle, floating rpms, running really hot, runs better with choke = lean. Not revving, doesn't idle, fouling plugs, smoking allot = rich

[@2STROKESTUFFING]

The millimeter rule of thumb should apply to most plugs.

[@thefrenchiestfry5495]

Hey 2stroke stuffing, i have a moped (Rieju Rs2 Matrix) and i recently put a 73.5 cc kit and 21mm carburetor on it and it runs Good, if i full throttle it, otherwise it sputters a bit, i have a racing plug on it at the moment i think maybe its gap is too small or maybe i should use a normal spark plug. What do you think?

[@2STROKESTUFFING]

Maybe the needle is a bit lean, or even rich - try raising/lowering it and see if it helps.

[@naveedaka]

can you please tell which mixture is good for drag racing ...i mean wide open throttle application..lean or rich

[@2STROKESTUFFING]

Depends on fuel, typically 12-12.5:1 for pump gas.

[@YZDanne]

De var något nytt de ska testas på ny crossen när den anländer. månne de är samma som gäller när man kollar lågfart och halvgas? Intressant tips och intressanta videos du har! Tummen upp

[@2STROKESTUFFING]

Takker! Yep, samme for alle gassposisjoner.

[@dsimila1]

Best intro! Is there a good way to clean the insulator? If the insulator could be cleaned one could have a testing plug with a hole thru the threads.

[@2STROKESTUFFING]

I think it's possible with sand blasting but never done it myself.

[@johnconner8974]

More tech videos please

[@NI_TR_O]

The one thing i will say about you videos is your cinematography is amazing but your audio is now lacking in comparison to your video, i would suggest separating the channels and removing the background noise in something like audacity then re adding it to the video but other than that great video, and i wonder you can read the soot rings on glow plugs as well?

[@2STROKESTUFFING]

Thanks, and thanks for the tip! I might have gone a bit overboard with the compression too...

[@MrLegit]

@@2STROKESTUFFING nah, it was on point. Guff job.

[@kartingtrackdays5107]

i want to try this on my rotax fr125 engined kart,it has a centrifugal clutch which means i cant pull the clutch in,will it make any difference to the reading having to coast with the engine still turning but cut ignition?

[@2STROKESTUFFING]

It will contaminate the reading, but you'll still get ok results.

[@kartingtrackdays5107]

@@2STROKESTUFFING awesome thanks dude,love your channel,its with your help that i have ported the barrel with great results,hence the need to get it correctly jetted,currently running the 34mm dellorto with a 182 jet,im very close to optimum

[@2STROKESTUFFING]

👍 Thanks!

[@maxpower363]

An easier way to cut the plug apart is to hold it in a vice by its flats and run a 5/8" hole saw down over the insulator, to cur the metal retainer. Once the circlip is out, cut a little further and you'll be able to pull the complete insulator out of the body 👍

[@2STROKESTUFFING]

Good tip!

[@rideordie2736]

@@2STROKESTUFFING hey do you have an email I can send you a video or fb?

[@Mr.Riffian]

After messing around with different jets one realizes what a gem injection is.

[@jasonpearson4983]

Or a lectron

[@Duke-px2kk]

Underbart, tack.

[@ElmarDylong]

When you kill the engine at wot, how do you ensure that the spark plug doesn't get drowned in fuel and oil? What can you read from a soaking wet spark plug?

[@photobillyexplores]

Elmar Dylong I kill and cluch at WOT, I understand what your saying but close off and coast is going have the least impact on the plug I would have thought 🤔

[@ElmarDylong]

Reading a spark plug is no proper way to determine if your mixture is ok. It is like reading the tea leaves, but of course you can see if something is way off. An egt-probe is a more usefull an reliable way to see what is actually going on.

[@charleslittle458]

Elmar Dylong you're just not good at reading tea leaves I guess.

[@JerryLee..]

Elmar Dylong Partially true. EGT will spike at both sides of the best AFR for the engine. If your are able to add a WB (pretty hard on a 2 stroke due to oil fouling) you have a winner. EGTs are slow reacting compared b to WB sensors so it's challenging. Just my experience.

[@ElmarDylong]

The difference is this cvt, the engine operates at one point of the rpm range. There is enough time to get a reading from an egt. But for geared bikes what you say is true. WB and two stroke? No good. ;-) A CO-probe will work, but may still be ruined by oil. Best is to go with a few hundred good runs on the dyno, the numbers will show everything if you can read them. Guesswork can't be completely eliminated. Reading tea leaves is not for me, thank you! :-)

[@Keisshi]

Can you make a video about your favourite rums?

[@2STROKESTUFFING]

👍

[@frez777]

you answered my question

[@daveb1963]

As you say the insulator only shows results for general riding well is that most of us do on the road?

[@bramvermaat1453]

We do 99% of the time. And then we blow up our bikes when we climb a hill at WOT.

[@danielwoodgate007]

Can this be done before top end has been run in?

[@2STROKESTUFFING]

Sure, but it's a good idea to check it again after run in.

[@xperimental1974]

how to know if the ignition timing is correct by reading the spark plug?

[@soraaoixxthebluesky]

Or buy an open loop O2 sensors to further confirm your tuning.

[@klaversfmt7350]

isn't possible to read out from to exhaust temperature ( if you have one like a mychron 2t ) ?

[@2STROKESTUFFING]

Sure is, but you'll need to determine a baseline egt to shoot for.

[@KlaversFMTBreda]

Can you make a movie about how to determine your baseline egt? Or do you need to dyno it to do that? Most people I speak say you should aim at 600 degrees. But does this apply to all engines or is this engine dependent? I've got a iame x30 super ( 175 cc gokart engine ) equipt with the mychron 2t.

[@2STROKESTUFFING]

Added to the list!

[@slopike45]

Klavers FMT It's anything between 590-730c. For example, rotax dd2 evo i ran at max 720c, but with TM kz10b it would melt the piston at such eg temps. As far as i know and have seen, iame x30 super suffers from much bigger problems with piston reliability then the allready fragile 125 x30 so i would keep it on the cooler side

[@trueasdrewvn7132]

Nice, nice. nice.

[@2STROKESTUFFING]

Thanks!

[@vintagecarnews5899]

nice

[@jeangade5809]

The way it is done :) :) :) +- ;)

[@bellybutthole]

Can you read a reed?

[@NowAndyPlays]

for a serious note, when i open my throttle and i hit my top speed my moped stops firing until i lower the throttle.

[@MAG-bp6hj]

does it make a bleuhhh sound

[@1pelikone]

Probably running lean.

[@supertedogpriken]

Rev limiter.

[@dustinshort6207]

Andy [Xvixx] if you snap the throttle from idle, does it also do it then? If so, you're way too lean.

[@jonnyrox116]

Sounds a bit lean to me...

[@BJFadilah]

mantappppp

[@giulioex125e7]

2:16 I'M DEAD

[@fairytail6939]

afr meter is the best tool for easy tuning and accurate

[@naveedaka]

and how much is too rich??

[@Doompjez]

Where is the bearrddd?!! 🤤😣

[@fabiotiburzi]

Enable subtitles please!!!!!

[@2STROKESTUFFING]

Only auto generated subtitles available are english, sorry.

[@markhanson755]

Shame on the person that unlike this...

[@haaland80]

why can't you use the brakes after you kill the engine?

[@RockabillyRambler]

im under the impression that pulling plugs when hot can lead to stripped threads :/

[@aaronbrown2966]

maybe if the plugs have been in for ten years

[@NowAndyPlays]

If it melts does that mean I need less fuel?

[@CannondaleF700]

Andy [Xvixx] yes if it melts you need less fuel and more air. Also don't use too much 2stoke.

[@photobillyexplores]

Andy [Xvixx] if it melts it's lean... much more fuel needed... start rich and work down! it's the safest way

[@CannondaleF700]

Willspoony Roberts not true ! It needs less fuel and more air also very little amount of 2stroke will help Wide open throttle while you have done above

[@thealmosthdchannel]

Melting the spark plug is caused by the combustion temperatures being too high. This can be caused by a spark plug of the wrong heat range or by having too little fuel in the mixture. The fuel actually helps to cool down the engine before it burns which reduces the temperatures, and prevents melting the spark plug

[@CannondaleF700]

EdwardTennant Gaming He needs more air and less fuel and wide open throttle to clean the engine out!

[@MrDjcamo29]

So you must’ve figured out what was wrong with your SPX

[@bikelifemiami3055]

Check out my bike I’m studying the Jennings two stroke handbook so it’s mods based off the book

[@captainsledge7554]

Or buy an afm gauge

[@uap4544]

and expensive!

[@vojtechpilar5809]

I see all I need is a box of spark plugs and two weeks of my time to play around.

[@2STROKESTUFFING]

No free lunch...

[@motorboatmygoat9906]

Cool video but the plug you chopped was used and a poor example. People are going to watch this video and try to shoot for that dark ass ring from the used plug you posted. In your example the ring thickness is correct but the color is not for a WOT plug chop unless you do it 30 times maybe.

[@2STROKESTUFFING]

Thanks, and that's true.

[@23Roadster1]

Destroying a spark plug each time, just to read it for each throttle setting? Have you not heard of lighted plug magnifiers? They illuminate and magnify the base of the porcelain. No damage involved.I thought the whole idea of a motorized vehicle was to drive it at all speeds and loads. We can't concern ourselves with WOT only. Problems like detonation usually occur at lower speeds under heavy load. In any form of motorsport, you need to be working toward a high long flat torque curve. When you get that, the power number will follow, and the vehicle will pull hard all the way up.

[@joshuaharrison9331]

I googled this & they are just like doctors ear magnifiers. Imagining the scenario - you could never see clearly to the base of the porcine due to the extreme angle. Seems like people trying to sell a lemon tool to tools.

[@ludditeneaderthal]

How do you measure the width (which is actually depth in an unchopped plug) of the carbon ring? Just being able to see it isn't enough, you have to be able to measure it accurately. As a plug is only good for one run anyway, there is no advantage to "just peeking at it". If the expense of losing a dozen plugs is too high, then you shouldn't be power tuning anyway, because the practice requires accumulation of myriad bits whose final use will be gathering dust on a shelf.

[@dongerramarco9617]

that's one expensive method to approach life , mate

[@johnnym1320]

unless your reading a methanol engine then you read the color on the threads :-)

[@taylorsweet99]

Good video but his hat is bugging me.

[@jeremyhopkins6965]

Simple he says this guy SMH LoL I don't see how that ring could tell you anything being where it's at? And it being a new plug? I'm fr lost!

[@acurarl9929]

No timing read. Wat gives

[@kp4643]

This is expensive

[@2STROKESTUFFING]

Less expensive than melted pistons...

[@kp4643]

@@2STROKESTUFFING I think I'm gonna either run it rich or replace with stock carb. It's a Yamaha aerox moped bte

[@2tallB]

Off topic, but man, that guitar in the theme music is horribly out of tune. Fail. And I'm not talking about the use of vibrato bar. Thank you for coming to my Ted talk ;)

[@xedproable]

alcoholic much?

[@joshuaharrison9331]

If he can do all this work then I think not.

[@xedproable]

Joshua Harrison have it your way ass eater

[@2STROKESTUFFING]

I only drink when I drink.