Spark Plug Opinions

[Tiger Small Engine]

I will do that when the carb comes in and gets installed.

NGK plugs are my favorite. Then comes Champion, Bosch, and others. At the bottom of the list for quality and reliability are the cheap Chinese “Torch” spark plugs and knockoffs.

 

[Propflux01]

NGK plugs are my favorite. Then comes Champion, Bosch, and others. At the bottom of the list for quality and reliability are the cheap Chinese “Torch” spark plugs and knockoffs.

I usually immediately change out anything with a Torch in it.

 

[Propflux01]

Update: The carb is on. One minor adjustment and immediate startup cold. It runs good, but I will change the plugs tomorrow and get a new baseline.

 

[MarineBob]

I am not an expert but the difference in the two plugs is troubling. I am not familiar with the specific engine but I do smile when I read the comments about different brands of plugs. Only ABC for me, do not buy on Amazon...... When I was in my youth, we had no money to 'waste' on things like new spark plugs. For sure a Chevy 283 or a Dodge slant 6 was not the same sophistication as today's 2 L turbo engine, but all a spark plug does is provide a spark to ignite what is hopefully a properly mixed fuel mixture. For a small engine, as long as the spark is provided at some reasonable strength the brand should not matter. The heat range and depth is a consideration but on a small engine? I believe people are way too quick to toss a good plug when a soak in some solvent and a bit of cleaning with a proper gap gets it back to good operation. Anyway, my question with the pics is why the difference? I agree one looks hot, the other, more or less typical for a plug that just needs a cleaning. I guess my thoughts would be how long have those been in operation and is the result typical with a good running engine?

 

[mmoffitt]

Yes, both NGK BPR4ES. Single throat carb.

No FOD in the cooling fin area.

AF CrewChief?

 

[Savage3]

One thing I've noticed on those engines, the one coil always has better spark on one side then the other. The one plug also looks better then the other.

These facts have lead me to believe that the issue could be more related to the coils/spark/ignition then fuel. I've noticed it on several and have also seen several coils fail.

Just observations, no conclusive evidence.

 

[Mattmotors]

I guess the original plugs were unsat. We will need a sit rep when you are done.

 

[Gord Baker]

90 hours. I've never had to add oil. Plugs look a bit rich to me. FS600V. Choke fully retracted. Runs seemingly normal. No smoke (black or blue) when running or accelerating. Thoughts?View attachment 70913

Put them back in, opposite cylinders. Dark one is normal colour and no carbon buildup. Pull off the plug wire on the darkened plug side and see if it still runs. I suspect coil problems on the like new side.

 

[justin@justintime]

replace both coil packs with 21171-0740 left white plug used to look like the right one until it got washed with fuel. this assuming inatke is attached that cylinder isnt running hot for some other reason, valve adjusts, head gaskets, debris etc be willing it even runs on that cylinder (power balance test) kawia coils about the only ones I seen die as slow as they do and die quietly. This will be way over most peoples heads but I use a little handheld oscilloscope just cheap Chinese garbage but it does what I need it to do. I also have a pico scope. all inductive style spark or waste spark systems such as most v twins have all have a wave form all of which should look pretty much the same. Ive had muiltiple FS engines pass power balance test and run on each sindle individually and sound very similar with very similar rpm but just doesn't have the power it should. and get a wave form on each and have one look very different from the norm pictured below......dont get me wrong eventually the failing coil will fail but for now and probably a while one cylinder is doing alot more then the other, you'll probably also find old part numbered coils on there. do them both call it a day and move on. this is obviously after verifying all that and everything else.

 

[Savage3]

replace both coil packs with 21171-0740 left white plug used to look like the right one until it got washed with fuel. this assuming inatke is attached that cylinder isnt running hot for some other reason, valve adjusts, head gaskets, debris etc be willing it even runs on that cylinder (power balance test) kawia coils about the only ones I seen die as slow as they do and die quietly. This will be way over most peoples heads but I use a little handheld oscilloscope just cheap Chinese garbage but it does what I need it to do. I also have a pico scope. all inductive style spark or waste spark systems such as most v twins have all have a wave form all of which should look pretty much the same. Ive had muiltiple FS engines pass power balance test and run on each sindle individually and sound very similar with very similar rpm but just doesn't have the power it should. and get a wave form on each and have one look very different from the norm pictured below......dont get me wrong eventually the failing coil will fail but for now and probably a while one cylinder is doing alot more then the other, you'll probably also find old part numbered coils on there. do them both call it a day and move on. this is obviously after verifying all that and everything else.


View attachment 70966

Good stuff, I've had the same results with my scope.