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Yz125 Wont start

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Hey guys/girls

So i bought a used 04 yz125, the bike was running fine a day ago, it started on the first or second kick. 

After giving it a good wash the next day, it doesn't want to start. (fuel on, choke on and plenty of kicks)


the spark plug is black and wet and I don't know what to do to get it running again.  :excuseme: 

Im new to dirtbikes, and any help would be appreciated

thanks !!  👍

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Lol id start with a new plug obviously and have someone take your carb apart to inspect/adjust your jetting in accordance to your altitude/temp and so forth. No expert here but you didnt mention how long youve had the bike or how long youve ridden it before this "wash" that killed your bike. Also good to mention what the overall condition the bike and air filter are in. What did the seller have to say about it? Maybe a couple pictures? People on this forum love details and specifics. Without them, generic questions lacking information are ignored. Wish you luck with your YZ im sure you can make a badass machine using passion, determination and this forum 🙂

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I was able to get it working again, seemed like it was flooded so i turned the fuel tap off and tilt the bike over allowing fuel to spill out the hose til no more dripped out. I started it up and let it run with the tap still off getting rid of the fuel thats still left in there, when it died out i started it back up with the fuel tap on and it starts first kick 🙂


should i rebuild top end ASAP?? and what else should i do to the bike besides changing the rear tyre (no more tread) and adjusting the chain (slightly loose)


I bought the bike 2 days ago and only ridden it up and down the street on inspection and when i got home. I dont have any experience with 2 strokes but when i was riding, it was running pretty sweet, everything felt smooth? unless smooth is a bad thing on 2 strokes then uh oh... The condition of the bike is good, no leaks (except for slight leak on front forks, when i hold the front brake and push down on the front end i see remainder of fluid stick to the silver pole thing..sorry i dont know the name of that part but is that normal to have left over oil in that spot? ), no cracks, just a few scratches on the plastics. It's got a Twin Air filter, I gave it a wash and applied air filter oil.



The owner said he bought it off another guy, 10 months ago. he told me he put new bearings on front and rear wheels, new renthal sprockets, twin air filter, tag t2 bars and bar risers. he changed the fuel filter and gear box oil one ride ago





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I would strip the front end off and check and grease the steering bearings , strip the suspension linkage and swingarm off and check and grease all the bearings , and replace the ones that need replacing.


If the owner cant give proof of last piston and ring replacement then take off the barrel and measure the piston and replace the ring or even better replace the piston and ring, while open check for play on the conrod.


Bike does look very neat in the pics but that doesnt mean all that i have mentioned is still good.     

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Wow your bike looks almost exactly to my 02 🙂

I can give you basically a checklist of what might be good to check:

1) What Shawn250 said, All of it.
2) Check front and rear wheel bearings too, inspect, grease, replace where needed.

3) Carburator probably needs a clean up.

4) Get the service manual, and start greasing, inspecting, tightening everything.

5) Never trust the previous owner :D

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