2 stroke spark plug color chart

Pb_user_/ October 2, 2012/ 2 stroke spark plug color chart/ comments

My friends at OSDparts. If you have one, contact me with description and price. Have you had a bad experience with a dealer, repair shop, or engine rebuilder? If so, now you can post your experiences here. Hopefully this page will help others avoid the same fate!

Check out this Gauge repair kit! Jet Pump Rebuilding Services. PWC Engine Ref. Change your pump oil every 50 hours and you'll save money in the long run! Battery dying in your Trim equipped up Sea Doo? Disconnect your VTS unit. If that fixes the problem the module probably has failed due to moisture. Every time you have your engine compartment open, grab the motor and give it a pull to make sure your motor mounts are in good shape. Broken mounts can cause driveline and pipe problems if not caught early!

Save money and time by doing repairs yourself instead of using a dealer! The area above is always changing so check back often as links are added. Spark Plug Reading Info. This info mainly pertains to 2 strokes at this time but may be updated at a later date.

Reading your spark plugs is a valuable tool for performance tuning as well as for identifying possible problems with the mechanical condition of your engine. Below are descriptions with pictures of different plug appearances and their causes.

Later I'll be adding a section on plug reading as well. Normal Appearance - This is a perfect plug.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. It only takes a minute to sign up. If I'm using a spark tester with an adjustable gap set to the correct gap for my car's ignition system voltage, what should the spark look like?

I ask because I've seen conflicting opinions on this matter. For example, this Brigg's and Stratton site says:. A bright blue spark is best. Not true. Spark color determines virtually nothing. The hottest spark is ultraviolet which we can't see. Blue spark is cold in comparison to ultra-violet. Orange and yellow come from particles of sodium in the air ionizing in the high energy of the spark gap. However, they are talking about small air cooled engines, and are using a specific Briggs and Stratton spark tester with a fixed gap for small air cooled engines, the model.

Here's another person saying spark color doesn't matter:. I might note though that the very fast, very high voltage sparks in todays systems usually are not blue. Your mileage may vary. This poster on another site responding to a similar question about the above Briggs and Stratton quote says :. On an automobile ignition system the spark should be bright blue. That's because the compression ratio is higher than that on an air cooled small engine.

An automobile engine operates under a transient condition where the RMP's change so fuel demand changes.

Spark Plug Reading Info.

Where with most air cooled small engines they operate under a static condition or a steady state. Compression ratio of an engine and the amount of fuel being delivered can have an effect on how well the spark plug fires. This is called quenching the spark. A low compression engine running at a steady state with a constant fuel supply won't quench even a spark plug with a yellow spark.

But on an automotive engine with a higher compresssion ratio and under transient conditions the yellow spark can get quenched thereby causing a misfire. Here's another guy saying basically the same thing :. I use mine in line between the spark plug installed normally in the engine and the plug wire. You can then also increase engine rpm to verify spark at higher speeds. My experience has shown a strong blue spark with a noticeable popping noise in a healthy ignition.

The gap is determined by the amount of voltage generated by the ignition, spark plug gap, and the compression ratio. Most manuals will give an air gap recommendation for a spark test.

I don't have the background to tell who's right and was wondering if someone more knowledgeable could give me some verification here. Also of note is this answer on the physics stack exchange which says that the blue color of air sparks comes from ionization of nitrogen atoms. In fact, someone else has basically asked a very similar question over on the physics stack exchange:.

Is their a visual difference between air-gap sparks of the same voltage but different current? Many of years ago I had a moped which would not start. The helpful agent asked me "have you got a spark? What colour is it?If your spark plugs are fouled or damaged, it can lead to a host of problems including reduced gas mileage, slow acceleration, engine misfires and trouble starting the engine. If you are experiencing engine problems, taking a look at your spark plugs is a good place to start.

When reading spark plugs, you will likely find one of the following conditions:. You can do this as part of the routine maintenance of your car, ATV, lawnmower or boat, or if you suspect something is wrong with the engine. The first step is removing the spark plug you want to look at. Take the spark plug in your hand and begin looking at it for signs of damage.

Look at end of the spark plug that was in the cylinder and examine it. You will likely see one of the following conditions. A normal spark plug will have brown or grayish-tan deposits on the side electrode. Everything is just fine with your spark plug; you can reinstall the spark plug. Black, dry soot on the electrodes and insulator tip indicates a carbon-fouled plug.

2 stroke spark plug color chart

Black, oily deposits on the electrodes and insulator tip points to an oil-fouled plug. Oil could be leaking into the cylinders, getting past pistons that are worn or valve guides that are worn.

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Finding the source of the leak is very important — consult a mechanic for guidance. Once the problem is addressed, you can replace the spark plug.

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A wet spark plug can be the result of the engine flooding. Flooding is what happens when you try to start the engine several times without it firing up. You can clean the spark plugs or you can just wait for them to dry out. Blisters on the insulator tip, melted electrodes, or white deposits are signs of a burned spark plug that is running too hot. The spark plug should be replaced.Brown to grayish-tan color and slight electrode wear.

Correct heat range for engine and operating conditions. Causes hard starting in damp or cold weather and poor fuel economy. The voltage required to fire the plug has approximately doubled and will continue to increase with additional miles of travel.

Poor engine performance and a loss in fuel economy are traits of a worn spark. Blistered, white insulator, eroded electrode and absence of deposits. Results in shortened plug life. When these conditions prevail, even a plug of the correct heat range will overheat. Melting may also occur. Usually, the electrode surface is rather lustrous and uneven.

Nickel alloys melt at between and deg. Melted electrodes. Insulators are white, but may be dirty due to misfiring or flying debris in the combustion chamber. Can lead to engine damage. Check for the correct plug heat range, over advanced timing ignition, lean fuel mixture, insufficient engine cooling and lack of lubrication.

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Usually one or a combination of several engine operating conditions are the prime causes of pre-ignition. It may originate from glowing combustion chamber deposits, hot spots in the combustion chamber due to poor control of engine heat, cross-firing electrical induction between spark plug wiresor the plug heat range is too high for the engine or its operating conditions.

Insulator has yellowish, glazed appearance. Indicates that combustion chamber temperatures have risen suddenly during hard acceleration. Normal deposits melt to form a conductive coating which can causes misfiring at high speeds. Insulators may be cracked or chipped.

2 stroke spark plug color chart

Improper gap setting techniques can also result in a fractured insulator tip.The following is reprinted from Cycle Magazine, October Nearly all of it is just as pertinent today as it was twenty years ago. Thanks to GJ for all the great tech articles over the years, and for permission to reprint this one. Stay with motorcycling long enough to swat a few gnats with your nose and you will at least begin to realize how much there is to know about spark plugs.

Bikers like to tinker, and will replace spark plugs even if they don't venture anything else. And in just replacing plugs the motorcyclist becomes acquainted with the fact that there is more than meets the eye.

The first thing you have to learn is that there are some important differences in spark plugs' threaded ends, which are made in four diameters and lengths. Most plugs' thread diameter is a nominal 14 millimeters, but Honda -for example- uses 10mm plugs in small displacement engines and l2mm plugs spark all the Honda Fours. There also are 18mm plugs, seen only rarely in motorcycle applications despite the advantage they bring to two-stroke engines.

At one time you had to cope with slight differences in thread configuration on spark plugs from different countries; this worry mercifully has been ended by an international standardization of thread forms.

Because differences in thread diameters are so large, few people get into trouble through trying to stuff a l4mm plug into a 12mm hole -or vice versa. The same isn't true of plugs' threaded lengths, or "reach. These dimensions are followed by engine manufacturers in the depths they give plug holes, and the idea is that the lower end of the plug's threaded shank should come up flush in the combustion chamber.

One of the disasters you can have from using a long-reach plug in a short-reach hole is purely mechanical in nature. In time the plug threads exposed inside the combustion chamber may become filled with hard-baked deposits. If that happens you'll find it almost impossible to remove the plug without also removing the plug hole threads.

Reversing this kind of mistake, using a plug reach too short for the hole, lets deposits fill the plug hole's exposed threads and may cause difficulties when you try to install a plug having the correct reach.

2 stroke spark plug color chart

The worst and most immediate problem created by an overly-long plug in an engine is that the exposed threads absorb a terrific amount of heat from the combustion process. This raises the plug-nose temperatures, and may take them up high enough to make the side electrode function as a glow plug. And when that happens you have the white-hot electrode firing the mixture far too early, like an over-advanced spark timing but worse because the early ignition causes yet higher combustion chamber temperatures, which causes even earlier ignition.

This condition is known as "runaway pre-ignition," and if it is allowed to proceed it will wreck your engine.One of the things that makes Old Timers scratch their heads, and newbies cook engines, is the complex interaction between prop load and 2-stroke carburetor jetting.

Here are a few basic principles, and pictures of some sample spark plugs to look at. The prop load, and only the prop load, determines maximum RPM. If engine RPM changes, then the engine has lost power, or something has happened to cause some change in the prop pitch. CHT is a function of jetting and load. CHT can be reduced by larger jets, or a reduced load. It can be increased by smaller jetting, or increased load. This assumes an otherwise healthy, normal engine, correctly cooled and operating properly.

EGT is a function of jetting and load. EGT cannot usually be reduced to normal in an engine that is under propped and overrevs. In such an engine, EGT will almost always be too high. The correct action in such a case is to make sure jet size is sufficient, then increase the prop load. Simply increasing the jet size is chasing the symptom and ignoring the cause.

Spark Plug Color Chart - Reading Your Plugs

In an engine that is correctly jetted, a high EGT will decrease to normal as prop load increases to correct settings. A correctly propped engine will typically be able to just nudge RPM red line at full throttle in level flight. An engine that is over propped over loaded and unable to attain normal RPM may frequently exhibit EGT values below normal, while CHT values can vary from normal to high to very high.

The solution is to adjust the prop load. Once again, this assumes an otherwise healthy, normal engine, correctly cooled and operating properly.

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EGT can increase to damaging levels in an engine that is correctly jetted, but is artificially leaned out by overrevving in a fast shallow descent. What has happened is that the fuel supply is less than half normal the needles are down into the jetsand although the slides are partly closed, air volume is artificially very high due to the high RPM, the prop turns the engine into an overactive air pump and the engine mixture becomes greatly leaned out.

Now you have a situation of low load, high RPM, high carburetor air flow, and low fuel. This equals very high EGT levels, use caution. If EGT levels rise unaccountably, or an engine appears to need unusually large jets to avoid high EGT readings, look for an air leak. If one cylinder's EGT unaccountably rises above the other, look for an air leak specific to that cylinder.

If both cylinders EGT's rise with a single carb engine, check the intake manifold.Just needed some text that was readable. The pictures and text are from the Autolite technical manual and just made a bit easier to read in the grand scheme of EZ-Read charts here. This is a simple re-hash of that with mostly the same text as the original from Autolite.

The pictures are about as good as I could find on the web, and guessing these are 30 years if a day. The plugs are numbers as in the Original Autolite book page as is the text, again not taking any credit for these Autolite did the work.

Wish I had some better pictures, but what can you do. When in doubt change the plugs if you can. You ask what type of plugs I use? Fan of either brand, but I'm not so picky that I wouldn't use Champion or other brands. I just prefer Autolite and NGK. Here is a Tool Review on Spark Plug Magnifierswill help read the plug as our eyes start getting worse!

All Rights Reserved. Content May NOT be used without written permission. Use at your own risk. Normal Plug Correct heat range of spark plug is being used. Replace with the equivalent Autolite spark plug at the proper interval. Appearance - Grayish-tan to white color. Normal With Red Coating Coloration is from the use of additives in unleaded fuel.

Spark Plug Types - NGK Spark Plugs - Tech Video

Appearance - Pinkish-red color on the ceramic insulator tip, the center electrode, and the ground electrode. Fuel Fouled Indicates the cylinder from which the spark plug came is not using all the fuel supplied to it.

Check for faulty or sticking choke, overly rich fuel mixture, ignition problems, leaking fuel injectors, or spark plug heat range is too cold.

Appearance - Firing tip is damp with gasoline, usually the odor of fuel is present on the spark plug. The insulator is often tinted the color of charcoal. These usually look WET and smell of gasoline. In race cars make sure you check the plug after a quick shut down.

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I find that I get a bit on the fouled side not as bad as this when stuck at idle due to unruly camshafts and such. Detonation Caused by low octane fuel or over advanced timing.


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