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yz 125 wont start

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I bought a used 98 125 off a guy who blew out the top end. He score the jug and piston. So i went ahead and bought a used 55mm bored jug with piston to match. They were used and the bore measured 55.08mm.

 

I just finished the rebuild with new gaskets, new oil, coolant etc. Second kick, it started for a second with choke open, then died.

 

I havn't been able to get it going since. 

 

Pulled the plug, had spark, replaced the plug anyway. Everytime i pull the plug, its wet with fuel. 

 

Went and got a compression tester, and it reads 135psi. Not the best, but better than most. 

 

I am not sure what else to do? Can anyone help me out

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Your rings might not be seating properly for a full seal. Could be a carb problem. I have had problems with bikes before that the plug was wet with full and wouldn't start. Turns out it was a pilot jet. Look into it

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i pulled the card out tonight, but honestly i'm not sure what im looking for. I dropped the bowl, float all looks nice and clean, i sprayed out every nozzle and pulled both the pilot and the main, and they look fine. put it back together and still no luck. I also pulled and cleaned the reeds, and also dropped some fuel in the spark plug hole, but it wont fire still....

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Considering that the plug is coming out wet that you are getting too much fuel or a spark that is too weak. However you are about 50 psi short of where my 125 tests even with a 10 hr (very hard hours) top end.

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even at 135 i should have no problem with it firing up. any other ideas? 

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As I said... either too much fuel or too weak of a spark. Try replacing the plug boot. I've had several go bad on several Yz's. Like a $3 part and can cause worlds of headache. 

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Alright thanks, I will try that. Also, i found out i am missing part number 35 off this pictorial. Its the seal for the power valve, this wouldn't have anything to do with starting the bike would it? my powervalve is all hooked up, but i am missing that part.

 

http://www.motosport.com/CA/dirtbike/oem-parts/YAMAHA/1998/YZ125/CYLINDER-HEAD

Edited by purcell1

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Alright thanks, I will try that. Also, i found out i am missing part number 35 off this pictorial. Its the seal for the power valve, this wouldn't have anything to do with starting the bike would it? my powervalve is all hooked up, but i am missing that part.

 

http://www.motosport.com/CA/dirtbike/oem-parts/YAMAHA/1998/YZ125/CYLINDER-HEAD

Has no effect, but you should def replace it. You can actually run the bike with the cover removed. I have done it quite a few times on my Yz's to make sure that it is opening and closing properly.

Edited by BDubb106

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My bike had the same symptoms and it turned out the needle valve and seat were really worn, i would buy a carb rebuild kit and go through it

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i think it's deffinatly giving too much gas into the combustion chamber, brand new plug after one kick with the choke off the plug comes out soaked. 

So how do i go about adjusting this? With the plug out i turn gas off and kick about 20 times to try and clean some gas out, but the float is still full probably feeding fuel still because it stink of gas when i kick with the plug out. 

 

Thanks for the help thus far guys!

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i think it's deffinatly giving too much gas into the combustion chamber, brand new plug after one kick with the choke off the plug comes out soaked.

So how do i go about adjusting this? With the plug out i turn gas off and kick about 20 times to try and clean some gas out, but the float is still full probably feeding fuel still because it stink of gas when i kick with the plug out.

Thanks for the help thus far guys!

you need to check the float height and your needle seat for wear. As mentioned above, a rebuild kit would take care of it easily. Edited by BDubb106

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Well It runs great! Just wanted to thank you guys. It turns out it was just flooded. I pulled the plug and kicked like hell. Waited a half hour put a new plug in and she fired up first kick. I had trouble with the idle, but now that i found the idle screw it is dialed and ready for a long weekend of fun!!!

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