Something kills my spark plugs???

[Caddy 16v]

Hi,

I have a new/ old problem since my bike ('91 KX250) has now successfully killed two of my sparkplugs after around 1h of ride time! I can't really go anywhere without having to worry that I'll die and I'll be pushing for a long time.

The thing is it gets gradually worse, with a new plug it runs crisp and then starts to bog every now and then until it finally has no more spark. When I test the plugs on another bike they are still dead.

I have a suspicion but want to hear your suggestions as well: I'm running a '91 igniter and ignition coil but the bottom end is from a '89 so there is a '89 stator in there and I suspect that is not playing along as it should and kills the plugs!?


Thanks in advance.

[Openclass]

What color is the plug after you remove it? Black/wet would mean your jetting is to rich.

[81cr450]

X2 on jetting, spark pretty well works or it doesnt.
Also if youre running a really cold plug & lugging around that would exacerbate a jetting issue.

[Caddy 16v]

I was running a bit rich (dark black color) for a while and the plug was wet at times but yesterday I changed it and it was dry after that, might have been already gone too far? First it was a NGK B9ES and then a BR9EIX iridium plug.

[81cr450]

If I'm trail riding where there is alot of lugging & not alot of winding it out I'll run a br7 generally I run a br8 but I do jet a bit rich for my elevation. You do need to pull the carb & check the jet size though. Baseline with a kehin 55 pilot, 170 main, middle clip, with no regard to your elevation temp etc...

[Caddy 16v]

I think a hotter spark plug might work I should give it a try. Thats how the plug looked like when it died:


and the previous one:

[81cr450]

Jetting

Someone else wanna chime in here

On the plug I'm at 5500' plus all the time so I dont know that it is for everyone as I run a bit rich, rather safe than sorry but , 15-20 hours is a plugs life in my oppinion not an 1hr. If I do run a quality synth blend oil like klotz though they last even longer

[Marco810]

Plug looks soaked, too much fuel

[sylvester]

Check the stator and coil cold, put a new plug in untill failure and recheck stator and coil with ohm meter. If its getting progressively worse the electrics are probably failing under heat sooner aand sooner. If it were jetting, I believe it would be problem from the start. The plug will appear soaked if not enough voltage is shooting through.

[Marco810]

Check the stator and coil cold, put a new plug in untill failure and recheck stator and coil with ohm meter. If its getting progressively worse the electrics are probably failing under heat sooner aand sooner. If it were jetting, I believe it would be problem from the start. The plug will appear soaked if not enough voltage is shooting through.

good to know. would make sense to start at the electrical

[russ]

some one once told me that if your spark is blue its good af its got any white in the spark its a gas soked plug time for a new one and if its red spark its your coil that what i know and thats the colour of the spark not the spark plug

[Caddy 16v]

Thanks, I seem to remember that the colour of the spark is blueish, I got a BR8ES today so hope that will help. Right now I'm at a 168 main with the needle on the first clip from above since the third and second clip totally soaked it. I'll have to check what size pilot is in there though. I think I'll still have a 165 main hanging around somewhere.

If it should still die early I'll try a spare coil and ignition.

[Caddy 16v]

So it had a 55 pilot jet in there, I had a 52 laying around so I went for that one, it seems to run a bit better now and the color changed to a dark brown/ blackish. It seems like a 50 pilot jet was the smallest available for that year, so could I even go smaller since they make them smaller??

[Motorrad]

I think a hotter spark plug might work I should give it a try. Thats how the plug looked like when it died:


and the previous one:

Wow.. You have longer fingernails than my wife.. 

[Caddy 16v]

lol I had to cut them later, they were annoying