HELP!!! Bike Keeps Ruining Spark Plugs!

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#1
I just got a Yamaha YZ125 about 2 weeks ago and I have already gone through 2 spark plugs! I am not too familar with dirt bike motors, especially 2-stroke motors. I know 2-strokes like to eat plugs fast, but I don't think it should be that fast. Give me as much info as you can! Thanks!!!!
 

Chili

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#2
Do a search for "jetting" and you'll get some answers. 2 strokes do not eat plugs if they are tuned properly.
 
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#3
Same here, I just ruined a plug today, but I think it was my fault. Tell me if this sounds normal.......I was riding on silver lake trail in Tallahassee, Fl.......and all of a sudden I run into a cliff thats about 7 feet high, with a little lake below it.......so I panic, hit the front brake and throw the bike down. It fell on its left side (if you are looking from behind) the idle is a little high so its still running (i guess the clutch was in while it was laying in the sand) while I'm standing there looking in shock, knowing I almost fell in a damn lake. So I pick it up, then it shuts off. I try to restart it, nothing....I fouled the plug. What could have happened? Did the plug drown while the bike was on its side (if thats even possible)?
 

Chili

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#4
The bike was likely simply flooded, to start a flooded 2 stroke hold the throttle wide open and kick.
 
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#5
I did that.......it start for like 2 seconds, started sputtering, I gave it as much gas as I could, then it just shut off. Got back to the truck, put the bike under a shaded tree to check for a spark, and nothing.
 
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#6
I have had the same problem in the past. I think the first reply I had is the trick to the problem. Also, the carb probably needs cleaning. I guess I wasn't thinking clearly because my 2-cycle trimmer and tiller have the same problems if the carb needs cleaning or if they are tipped on the side. The plug gets too much oil on it and can't spark.
 
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#7
I ran the same plug for 1 1/2 years on a KX250. This is confirmation that 2 strokes do NOT eat plugs.

Check the spark plug boot on that RM, they can wear out and are very easy to replace.
 
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#10
did you ever have this problem with your yz125? did the JD jetting kit work this problem out?
 
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#11
i dont have one, but its next on my list of things to buy. when i got my yz the jetting was still stock but i never fouled a plug, but i leaned the clip on the needle one notch and dropped the main jet down a few sizes.
 

Chili

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#13
You don't need a JD jetting kit. If you use the search function for "jetting" and "spooge" as your search terms you will find enough information to teach you how to fix the problem for nothing more than an investment of your time and anywhere between $0-$20 worth of parts. Fox forks has even saved you some time by giving you links to two threads full of jetting information.
 

Chili

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#14
sixds said:
i dont have one, but its next on my list of things to buy. when i got my yz the jetting was still stock but i never fouled a plug, but i leaned the clip on the needle one notch and dropped the main jet down a few sizes.
So you've already adjusted or know how to adjust your jetting, why on earth would you pay $75 USD for a JD jetting kit at this point?
 
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#15
my problem wasn't jetting at all. i took it back to the dealership where i bought it and the mechanic looked it over. when they put the new motor in it, they put the wrong spark plug in it. they put the right plug in it this time and didnt charge me for it because it was their mistake. he told me to take it home and run it hard, and bring it back if it dies. it hasnt died yet and seems to have a lot more power.