Yamaha yz125 won't spark

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Mar 30, 2008
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#1
I just bought my 14 year old son a 2004 yamaha yz 125 and it won't spark. The guy I bought it from said he quit riding it in December and it ran fine. He said he cleaned out the gas tank and put new gas an oil mixture in it and he cant get it to spark. It will try to crank when you try to start it it just wont spark. He did the new plug on the motor thing and still no spark. Its a nice bike if I can get it to run, do you have any suggestions. Also the kill switch has been cut off and the wire is bare but down in the plastic cover. Also what is your opinion of this bike.
 

biglou

#3
It's an awesome bike. First things first: Replace the spark plug, and buy 2-3 extras, you'll need them eventually. Then, make sure the gas is on (fuel petcock under the left side of the tank), choke is on, then try to start it. If you have a fouled plug in it now, it will never start, and you'll just be wasting time and energy.
 
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Mar 27, 2008
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#4
im having the same problem with my 2000 yz125

sounds like the same situation also

ya im tryin 2 find out how 2 get mine started also
so if u get urs started tell me on my profile wat u did

thanks
 
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Jan 31, 2008
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#5
dirtbikemom,
Make sure the wires from the cut kill switch aren't touching the frame or anything metal. I'm not sure if there are two wires or just one, but if there are two make sure they are not touching each other. Where the coil is bolted to the frame clean under each bolt until you can see good clean metal. bolt the coil back on; I like to use a bulb or dielectric grease under the coil/bolt area. This will keep this area clean from rust and bad connections. Check all of the connections to the other parts of the ignition system ie the black box and the already mentioned stator. If these things look good then you will have to check the firing coil that is in the stator area. If you have a shop manual it will tell you exactly how to troubleshoot this problem. Hope evrything works out and keep us posted! :cool:
 

Coop

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#6
First thing like ohmthis said is replace the kill switch. When I was working in shops I saw many improperly removed or faulty kill switches being responsible for no spark. Most people don't think to check it for some reason.
 

XRpredator

AssClown SuperPowers
Damn Yankees
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Aug 2, 2000
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#8
biglou said:
And none of you would change the sparkplug first?
well, you probably should try rebuilding the top and bottom ends, relace the wheels, repack the suspension and wheel bearings, and have the suspension fluid and fork seals changed.

But, just to see if it starts, I'd replace the spark plug first.
 
Likes: Jerrel

Jamir

I come and go
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Aug 7, 2001
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#9
D'oh!!!! I sold my bike for half the price I bought it for because of this problem! No wonder that guy was so excited to get it.
 
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#10
If I understood what he said correctly then he already put a new plug in the bike...
If not, then yes, new sparkplug, new killswitch, and go from there. Also check and make sure that the sparkplug cap is connected properly to the wire and that the cap clips onto the sparkplug tightly.