I was wondering if anyone out there could tell me why a 97 400 explorer would keep killing it's spark plugs? My uncle bought this bike used and the thing is in mint shape but he is lucky if he can get 1 hour out of a brand new plug.Once he puts another new plug in it will run fine for maybe 1 hour and then the plug is dead again! He is not sure what he should check/replace so I told him I would check here on the forum for any possible solutions.THANKS TO ALL REPLIES.

 

explain what you mean by eating plugs? loosing fire, fouling, breaking electrodes?

 

The plug loses it's fire!
If you put a new plug in after about 1 hour the bike will just shut down with no spark, the plug is not damaged or burnt! He has had to put in numerous plugs just to go for a 2 hour ride. The plugs look like you just took them out of the box, but with no spark. As soon as you put in the new one it will fire up in a split second. He has tried some of the old plugs for spark but once they stop they are no good! Sorry for not explaining myself more clearly but I'm also trying to diagnose his problem via e-mail. THANKS AGAIN

 

no problem w/ explaination, just couldnt under stand. ive never heard of anything doing that before. the only thing i could think of is theres a coil issue putting out way too much fire. but i dont under stand how it would hurt the plug. hes using the right plug, meaning the correct heat range? maybe has cdi issues. thats a good stumper question. hope some one chimes in w/ a good result for ya.

 

If the plugs look "like new" after being run for an hour,,, It's almost got to be improper heat range plugs. They should have somewhat of a color change.

Also, is this a 2 stroke engine? If so, I would also look into the oil injection. Maybe try premixing a gallon and take a test drive??? I doubt this is the problem but it should be eliminated just for peace of mind.

 

i have the same problem on my dr350 suzuki 4 stroke dirtbike ..
although it can last 3 months or 2 days i'll load it on the trailer running fine and get to the trails and have no spark, plug looks new but acts shorted out, change it and fires up like new again till... who knows.
one thing i did notice when i got the bike the battery was out and the lights were disconnected, i hooked all the lights up and added a sealed batteryand it worked fine till i noticed my new sealed battery was buldging and looked like it was ready to explode.. i removed the battery and the lights still worked while running but the plug problem still persists

the point is i am stumped too

rich

oh back to your problem,
i parted out a 95 400 xplorer awhile back and still have all the wiring and electronics i'm sure, if they are actually interchangeable let me know what you need and make me an offer

 

you should try to see if theres some kind of test for output of the coil to see if its in the proper range its suppose to be. also where its a 2 stroke becareful not to run it too lean and hot to burn it down.