Spark plugs, why do they fail...?

[Norway]

Can anyone explain why spark plugs seem to just give up....?
Went riding today, all seems fine, bike starts easy as allways.
Rides for 30 min, quick stop, 5-6 min, then bike wont start....
Innvestigating, and no spark...
Replaces spark plug, all is fine again.
Less than 2 hours on this plug, NGK br 9 es.
Same thing has happend before, also on other bikes,
and in my snowmobile.

But there dont seem to be any reasonable patern,
ran my previous spark plug for a long time...


Bj?rn Ivar

[Polar-Bus]

Can anyone explain why spark plugs seem to just give up....?
Went riding today, all seems fine, bike starts easy as allways.
Rides for 30 min, quick stop, 5-6 min, then bike wont start....
Innvestigating, and no spark...
Replaces spark plug, all is fine again.
Less than 2 hours on this plug, NGK br 9 es.
Same thing has happend before, also on other bikes,
and in my snowmobile.

But there dont seem to be any reasonable patern,
ran my previous spark plug for a long time...


Bj?rn Ivar

Usually rich air/fuel mixture oil fouling, and /or excessive low speed  driving. I have a NGK B8EG that's almost 2 years old still burns perfect. I am also jetted much leaner than stock. Race fuel also helps for a "cleaner" burn, but not necessary to eliminate plug fouling

[don46]

You could try a br9evx they are a bit more money but seem to work better than the es series, they are the fine wire platinum electrodes. Good synthetic oil helps prevent fouling, but in the end its about the jetting more than anything else, I guess in afterthought I would also say that there could be electrical issues ie weak spark

When the 89 KX 500 came out I bought one, I couldn't get the needle I wanted at the time so I waited and everytime I rode it I fouled a plug till I got the needle, it would start idle and as soon as I went to leave it would foul out a plug. after jetting no issues

[oic0]

I usually clean mine up and pop em back in. I don't know if it's advisable or safe, but I often burn mine clean with my stove top or gas grill

It also helps if you let the bike clear its throat every now and then. Just cruising around? get her into the powerband for a second every now and then.

[Coyote13]

I have had better luck with the br8, they are one step hotter than the 9s you are running. This in addition with proper jetting and you should not foul plugs.

[bob larry]

Ya toss all your ES plugs and run EG... few bucks more but way better plug
my $0.02