spark plugs??

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TractorDan
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spark plugs??

Post by TractorDan »

This is the age-old question; “What spark plug is the RIGHT plug for my engine?” I have a 2082 with a 20hp kohler twin engine. I have looked online for the right Champion spark to use and have come up with two answers 1) Champion RV17yc and 2) Champion RV12yc. So I turn the question over to the seasoned experts for advice? Any thoughts?
Thanks,
Dan
383 w/deck & snowplow
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ksanders
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Re: spark plugs??

Post by ksanders »

The RV17YC should be correct. I've only seen those and Autolite 26's in the twins. I have autolites in mine and just checked the conversion quick and it converts to the Champion RV17YC. I didn't see it in the 2082 owner's manual.
From the first Original to the last x82 Series... you can't beat an IH Cub Cadet!!!

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Tom Scott
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Re: spark plugs??

Post by Tom Scott »

Kevin is correct. The Kohler Magnum Service Manual specifies Champion RV17YC which crosses to an Autolite 26. I too like the Autolites and have them in all my tractors.

The main reason I posted is to warn that some Cub Cadet manuals specify the wrong gap for the plug, which will make for poor performance. The correct gap, per the Kohler manual, is 0.035".
1872, 46", 50C decks, Haban dozer blade, 450 snow blower
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ksanders
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Re: spark plugs??

Post by ksanders »

Funny you say that. Several manuals I have including the one I just looked up to answer this post say .025 which required me to gap them down from how they originally were and that's what my 682 is at I believe. Runs great but I may try changing it now.
From the first Original to the last x82 Series... you can't beat an IH Cub Cadet!!!

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Tom Scott
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Re: spark plugs??

Post by Tom Scott »

Kevin - Yeah, I remember we had a guy complaining on here of low power, and we determined he had that low plug gap. I didn't write wrong the number, just to avoid confusion, but that is it!

Anyway, the larger the plug gap will have more energy in the spark. Obviously if the gap is too large the ignition system will not make enough voltage to jump the gap. So the largest gap that will always fire is what you want.

Both my Magnums are set at 0.035" as per the Kohler manual, and they run great. I have to believe that the Cub manual is a misprint; the low number is just wrong.

Here is the Kohler Magnum Service Manual, if anyone needs it: http://www.kohlerengines.com/onlinecata ... 2204_b.pdf Page 3.5 for spark plugs.

Gotta trust Kohler over Cub. Plus, it has been proven by many that 0.035" runs great. The lower gaps do not always run right.
1872, 46", 50C decks, Haban dozer blade, 450 snow blower
2182-1, Kwik-Way Loader, 3-pt & rear pto, 442 tiller
2182-2, 54" deck, 551 snow blower
Past tractors:  1541, 2135
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TractorDan
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Re: spark plugs??

Post by TractorDan »

Thanks for the confirming the correct spark plug and identifying the correct gap. I read the same thing in my owner’s manual; they recommend the gap to be .025. But every other publication stated .035”.

Thanks,
Dan
383 w/deck & snowplow
2072 w/loader
2082 w/deck & plow & blower
1772 w/deck
128 w/deck
1949 Cub w/deck, plow, & snowplow
M-48 Tank w/deck & Snowplow
Mowett Mustang 5hp
71 w/deck

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Tom Scott
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Re: spark plugs??

Post by Tom Scott »

Bryan - Autolite does not show a number 826 plug. I suspect you added a digit accidentally.

One of the reasons I like Autolites is from my hot-rodding days... The Autolite numbering system and heat range chart is easy to follow. They generally offered a good selection of heat ranges in each size and the plugs had good durability.

That being said, I am not bashing Champions or anything else. I just like to stick with what I am comfortable with.

If you look in the Autolite heat range chart, there are other plugs with the same size spec as the number 26, but I don't believe they offer a performance advantage. Generally the platinum and other special plugs offer a longer life in automobiles, but from my reading the generic copper core plug still offers the highest performance. With much lower hour use than an automobile, wearing the plug is not a concern of mine, so I like the # 26 best for this application.
1872, 46", 50C decks, Haban dozer blade, 450 snow blower
2182-1, Kwik-Way Loader, 3-pt & rear pto, 442 tiller
2182-2, 54" deck, 551 snow blower
Past tractors:  1541, 2135
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BigMike
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Re: spark plugs??

Post by BigMike »

I know it doesn't seem possible but I have never had a Champion that failed on me.

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Tom Scott
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Re: spark plugs??

Post by Tom Scott »

Mike - I believe it. I think I had the Champion that came in my push mower for twenty years! I have also had them last for a long time in other equipment that came with them.

I only mentioned the Autolites for the Magnums because they have worked well for me in this application. Every now and then a direct cross doesn't work as well as another brand.
1872, 46", 50C decks, Haban dozer blade, 450 snow blower
2182-1, Kwik-Way Loader, 3-pt & rear pto, 442 tiller
2182-2, 54" deck, 551 snow blower
Past tractors:  1541, 2135
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red82s
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Re: spark plugs??

Post by red82s »

I noticed that the KT17 kohler manual calls for the rv15yc plug and .025 gap which cross references to the #25 autolite. Is that because it's a breaker point system instead of the magneto like the mag18 and 20? It gets better. After doing the auto lite application lookup, it says for the kt17 to use the #26 at .025 gap. That's what my 782 currently has so it must have something to do with the different ignition systems.
Adrian

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Re: spark plugs??

Post by vince_o »

Tom

Im going to check my gaps on mine and allens 1872's and see where thy are at. Im sure Im somewhere between 25 and 30. Ill set mine to .035 today and try it out. Thanks for the info.
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Tom Scott
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Re: spark plugs??

Post by Tom Scott »

Vince - Well???? This is an awful long time to wait for a report back on changing four stinkin' spark plugs! Maybe one too many jugs or mason jars this week?
:beer:
1872, 46", 50C decks, Haban dozer blade, 450 snow blower
2182-1, Kwik-Way Loader, 3-pt & rear pto, 442 tiller
2182-2, 54" deck, 551 snow blower
Past tractors:  1541, 2135
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Re: spark plugs??

Post by Farmallgray »

Adrian,
How old is your manual? I'm pretty sure Kohler recommends the RV17YC4 in all the flathead twins. I remember that from a Kohler service school in the early 1990s. That was an update from the orginal recommendation of the RV15YC.

I have had good luck with Bosch Platinums in my KT17 even though platinum plugs arent supposed to be good for point type ignitions (according to a Champion sales rep). The platinums actually cured a "hunt" that it had at part throttle when hot.
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Re: spark plugs??

Post by ghennessy »

Tom Scott wrote:Anyway, the larger the plug gap will have more energy in the spark. Obviously if the gap is too large the ignition system will not make enough voltage to jump the gap. So the largest gap that will always fire is what you want..
The larger gap doesn't increase spark energy. It increases the accessible area in which to start the flame front- the ground strap effectively "shrouds" the ionized air which allows the spark to jump. The coil or magneto delivers a fixed amount of energy. If the voltage isn't enough to jump the gap through an excited state path, the plug won't fire.

An electronic ignition, through more effective modulation of the primary coil circuit, allows for a sharper collapse of the magnetic field built up in the secondary circuit, producing more voltage, and more total energy than a points system (a function of dwell effectively). Voltage and energy (power in electrical terms) are not the same, though linearly related.

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Re: spark plugs??

Post by vince_o »

Tom

I changed Allens gap but really cant tell a differance yet. I dont have anything yet to put it under a load. Im pulling his eng today to possibly rebuild his steering for him. Keep you fingers crossed for me and the 3 springs
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Tom Scott
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Re: spark plugs??

Post by Tom Scott »

GHennessy - I stand by my earlier assertions. You obviously do have a good understanding of ignition systems, but I think you misunderstand this one point. Most of what I am going to write you probably already know, but a complete discussion is good for anyone else reading this that needs a primer.

Spark plug gap and the cylinder environment (pressure, mixture, temperature, etc.) directly controls the voltage that the spark will occur at. The plug gap provides resistance, and when the potential (voltage) builds to a high enough level in the coil (magneto) to overcome the resistance it discharges through the gap in the form of spark. Higher voltage ignition systems are popular with the performance car crowd, but if the spark plug gap and operating environment allow the spark to occur at a lower voltage, that is what you are going to get. Same with the higher voltage ignition systems you reference for modern electronic ignition systems; that is why GM increased the plug gap dramatically when they introduced the HEI ignition system.

The largest plug gap that will fire consistently within the entire range of operating environments of the engine's design is desirable because:
1) The larger gap increases the voltage required for the spark to occur; this produces a larger spark, and as you said, "provides more area to start the flame front".
2) The larger gap reduces quench. Quench is the robbing of heat and has two components, one from the spark itself, and two from the developing flame core. The robbing of heat from the spark is reducing the energy the spark can impart to the fuel it is there to ignite.

I do agree with you that a coil has a fixed amount of energy that it can deliver. My point is that the energy available to ignite the fuel rather than the heat the electrodes is what changes. The total energy does not change.

Our simple little magnetos really have a lot going on, and we could fill whole pages with tech discussion and get into the capacitive versus inductive portions of the spark discharge, etc, etc, but I never intended to start a fine point technical discussion here. The point is this: Cub Cadet was sloppy and printed a spark plug gap that does not agree with the manufacturer of the engine. Some (not all) who have used the tighter gap printed by Cub have had poor engine performance, and have had their engine performance improve when the plugs were gapped at the larger gap that was specified by Kohler. I am not recommending a plug gap larger than what Kohler specifies; they designed and engineered the engine and I am recommending that we follow their spec, not Cub's.

Vince - I am not really surprised that you did not notice a difference, as you had not noticed any problems previously. The tight gap suggest by Cub seems to be borderline and not affect all of the engines the same.
1872, 46", 50C decks, Haban dozer blade, 450 snow blower
2182-1, Kwik-Way Loader, 3-pt & rear pto, 442 tiller
2182-2, 54" deck, 551 snow blower
Past tractors:  1541, 2135
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Re: spark plugs??

Post by Farmallgray »

To back up what Tom said; I'm pretty sure the difference in the two champion plugs is that the RV17YC4 is designed to work with the wider gap.
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Re: spark plugs??

Post by indy61 »

I've never heard of a RV17YC4. There is a RV17YC6 but the specs look the same as the RV17YC. :?:

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Re: spark plugs??

Post by Farmallgray »

I had my numbers confused. There is no RV17YC4. There is an RV15YC4 which replaced the RV15YC. The RV17YC is what is currently recommended for the opposed twins.
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