Anyone using NGK CR8EIX Iridium plug or staying with MR7F for Sportsman 570?
I agree anti-sieze on the threads and die-electric on the terminal.Just my $.02..I always put anti-seize on spark plug threads. Just a smear..And usually some dialectric grease in the boot.
Was a mechanic at a Saab dealer in early 90's..I think a new head was about 3K...in 1991.
How often should these plugs be changed on these units? Is it by the hours or mileage?The MR7F is: 10mm diameter, 3/4" reach, 5/8" hex, projected tip, gasket seal, solid terminal top
The CR8EIX is: 10mm, 3/4", 5/8", gasket with a loose nut on a stud terminal and one heat range hotter
Both plugs are designed for and should be gapped at .032"
While there is no 'upgrade' plug listed for the MR7F, the CR8EIX can be replaced with the CR8E, CR8EB, CR8EK, CR8EKB and the CR8EIB-10
Of course it will create spark and the engine will run, but it would take a discussion with the engineers who designed the engine and the ignition system to know why they selected the spark plug they did.
The question is; Why do you want to run a plug other than what the manufacturer specified? What are you trying to achieve? Are you trying to overcome a specific problem? As long as the engine builder (you) accept responsibility for your choice of the spark plug's affect on (among other things) the ignition system (strength and duration of spark and life of system components), engine (performance, combustion pressure, combustion temperature and valve life) and choice of fuel necessary for acceptable combustion characteristics, you can run any damn plug you want to!
I have experimented with spark plugs, fuel, cylinder compression, valve timing, spark timing, ignition systems and pretty much everything else in search of performance and fuel economy. Rewarded by some and punished for others. One of my biggest mistakes was using 100 octane fuel in my CRF250 which was designed for 93 octane. It caused a loss of power, the exhaust ran exceedingly hot, fuel consumption increased and the fuel was $20 a gallon with a 5 gallon minimum. Through trial and error I determined the highest octane I could use without a loss of power was about 94.5. Since then I have settled on 91 octane non ethanol pump gas which is available at one of our local gas stations currently for about $3.30 (changes daily) a gallon.
If you are satisfied with your choice of spark plug, then it was the right one, but what works for you may not be the right choice for someone else. It's a personal choice.
Good to know, thanks.It can be done by routine or performance; routine, once each year, every oil change, every air filter change, after each outing - by performance, when it gets hard to start, starts misfiring, becomes fouled, fuel mileage decreases dramatically.
I ran the original spark plug in my CRF race bike for 8 years before I had any problems - the plug is $45 so I only change it when it is needed - after 8 years, the only problem I experienced is the engine would stall when chopping the throttle going into a high speed - it would restart as soon as the clutch was engaged, but I couldn't put up with the stalling - a new plug solved the issue - the second plug has been in use for 7 years, so I may expect to need a new plug soon, but I will wait till it starts acting up - as soon as it gets hard to start, misfires under acceleration or starts stalling on throttle closing, I will put a new plug in it.
yeah its running good fuel mixture wise but pic not really showing that its heat discoloration on threads, its not gunk . Not overly worried just wanted input. 👍Looks like good color to me. The color on the threads would be oil gummy gunk. Shoot it with starting fluid, it should wash off for the most part.
Tks, it was the Original plug, and you are right it was not very tight, but not loose either.Yeah - it pretty much looks like most every old NGK I've pulled out of every engine, but as close as I can examine the plug, it looks like it was under torqued - the crush gasket does not look like it has been crushed, but I can only see so much in a pic.
NOTE: NGK plugs are cadmium plated and do not require anti-seize like the plain steel Champion plug
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