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*****02 yz125 please help***

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alright i have a 2002 yz125. i cant keep it together to save my life. ive blown it up 3 times. clutch isnt slipping, im shifting so no over rev. it just wont stay together. help me

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Could you be more specific? What is failing? (Top end, bottom end, etc) What is your jetting at? What is your mix at? Theres a lot of factors that could contribute to this.

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Im running 4 ounces to a gallon. the piston keeps going out and tearing the head all up. i cant keep replaces heads every time it pops. the piston is really black, i know what they look like when they pop, but this one is really BLACK

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My 04 I ran:

Bel-Ray H1R, 40:1

Wiseco

Sunoco Ultra 94

BR9EG

and rebuilt it 3 times a race season ran perfect fouled 2 plugs. Start there though,Thumperkid questions should all be considered, and are key.

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yea i run the regular gas to break it in then change up to the 93 or 94 whatever it is, wiseco pistons

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You'll need to more specific. What is hapening to the piston? When you say it is black are you referring to the back side of the crown or the top of the piston? What else is wrong with the piston? Scoring or brown below the rings? Scoring of the cylinder?

93 and 94 octane pump fuel is ethanol enhanced octane ratings. Don't use it, it is garbage and ethanol causes lean running. Use the 91 octane or highest that you can get without ethanol, which is usually 91. You are running 32:1 at 4 ounces per gallon. Run a quality racing motorcycle premix not the stuff from walmart or chainsaw stuff. I suggest Yamalube 2r. But other quality premix's will do.

Be sure to warm up that Wiseco piston before you start tearing it up. It needs to expand with the cylinder not faster than the cylinder which is what will happen if you do not warm it up.

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You'll need to more specific. What is hapening to the piston? When you say it is black are you referring to the back side of the crown or the top of the piston? What else is wrong with the piston? Scoring or brown below the rings? Scoring of the cylinder?

93 and 94 octane pump fuel is ethanol enhanced octane ratings. Don't use it, it is garbage and ethanol causes lean running. Use the 91 octane or highest that you can get without ethanol, which is usually 91. You are running 32:1 at 4 ounces per gallon. Run a quality racing motorcycle premix not the stuff from walmart or chainsaw stuff. I suggest Yamalube 2r. But other quality premix's will do.

Be sure to warm up that Wiseco piston before you start tearing it up. It needs to expand with the cylinder not faster than the cylinder which is what will happen if you do not warm it up.

everything you said i agree with. BUT i use 93 octain fuel in my bikes and i have had no problems at all with it.. but you are right about about breaking in the pistions. if you dont let it warm up all the way then your going to mess your bike up..

i always let my bike warm up all the way befor i ride it.. if you dont then you will have problems down the road..

so can you give us some more information about whats happening to your motor besides its black and blowing up.. post up some pics so we can help you..

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yea i run the regular gas to break it in then change up to the 93 or 94 whatever it is, wiseco pistons

im just thinking here maybe your useing to low of octain and its predetating and wrecking your head or its not detating fast enough..

like i said i was just thinking please correct me if i wrong.

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