fouling a plug ?

[trailmarker]

on a 4 stroke, 4 cylinder how do you know if you have a bad spark plug or its not firing? or even when to change the plugs? i don't want to go throught the hassel of taking it apart. will the enging run rough? will you get a code?
my xcr ran 70 mph on 2/3 cylinders?

 

[watersuper]

First sign of a fouled plug is either hard starting or a rough idle. You may be able to clear it out by running across the lake after it has suffiecently warmed up.

 

[LJ 452]

You'll know, it as stated it will idle rough and will not have that sweat sound when idling. I would change them maybe every two to three years depending on how much ridding you do. Honestly you could go longer but what the hell it's fun working on the sleds this time of year. Besides nothing else to do to these things.

 

[rightarm]

Replacing plugs should be a yearly maintenance routine just like changing the oil,if you have a rough idle that could be a sign.I do not reccommend running on the lake to clear it out even if warm,think about it what's cheaper 4 plugs or a re-build.you can also put your hand on the cam cover and feel which cylinder is warm and which isn't.

 

[NY_SXR700]

I find that on my GT it will fart and pop on a plug going bad. It only happened once because a friend started it cold for 15sec and shut it off. NEVER do that, you must let it warm all the way up if you ever start it. Once it's good and hot it will always dry the plug off and not leave you on the trailer for the day.