Yz125

Blasterman16

New Member
Jul 24, 2012
46
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Nj
What Causing my piston to hit the head of my top end and digging it all up and its getting gas on my crank I only can see it when I take the to end off but when I check the oil its the right amount . And the carbrator is over flowing it's not going into the bowl . And the guy who did my piston didnt change that baring for the piston are these two thing causing all this the bike wouldn't even start .
 
Okay one thing the piston is hitting the head of the cylinder and the guy didnt change the bearing for the piston is that why it's doing that . That why I rather do my own work
 
No. The piston should not be able to touch the head unless the piston dome is incorrect. The only other thing that would cause this is if the head has been decked, or milled, down so far that the piston hits. I highly doubt that it has a stroker crank as they are VERY rare on the 125's.
 
More then likely he just bought a yz125 piston and not one for the right year. The yz cylinder, piston, and head have changed a lot over the years, if your running the wrong year piston or wrong anything else it might be causing this.
 
If the carb is overflowing it must be going into the bowl, that is where the needle and seat delivers the gas to.

You need to clean or change the needle and seat and set the float to the correct level.

There is supposed to be oil in the bottom of the crancase, that is how the motor is lubricated, by splashing around oil which has come out of suspension.

Were correct thickness gaskets put in, this would explain the piston slamming the head.
 
Could it be the. Crank ? And the gas isn't in the oil but on the top of the crank in it came out of the exsust what causing this and with the piston can it be that bearing
 
What Causing my piston to hit the head of my top end and digging it all up and its getting gas on my crank I only can see it when I take the to end off but when I check the oil its the right amount . And the carbrator is over flowing it's not going into the bowl . And the guy who did my piston didnt change that baring for the piston are these two thing causing all this the bike wouldn't even start .

Okay one thing the piston is hitting the head of the cylinder and the guy didnt change the bearing for the piston is that why it's doing that . That why I rather do my own work

Could it be the. Crank ? And the gas isn't in the oil but on the top of the crank in it came out of the exsust what causing this and with the piston can it be that bearing

What Causing my piston to hit the head of my top end and digging it all up
What do you mean by digging it up?

and its getting gas on my crank
By crank, do you mean crankcase, or crankshaft?

I only can see it when I take the to end off
Where are you seeing it?

when I check the oil its the right amount
What oil are you checking?

And the carbrator is over flowing it's not going into the bowl
It must be going into the float bowl, that is where fuel goes after it has entered the carb.

that baring for the piston
Are we speaking of the wrist pin bearing, big end bearing or crankshaft bearing?

Okay one thing the piston is hitting the head of the cylinder and the guy didnt change the bearing for the piston is that why it's doing that .
To my knowledge the wrist pin bearing has no relation to piston height.

That why I rather do my own work
If you wrench as well as you explain, I do not see this motor running well soon!

And the gas isn't in the oil but on the top of the crank in it came out of the exsust what causing this
Is the cylinder flooding due to a dirty or worn needle and seat, causing hydro locking, fooling you into thinking that the piston is hitting the head?

Gee I need a stiff drink.
 
What Causing my piston to hit the head of my top end and digging it all up
What do you mean by digging it up?

and its getting gas on my crank
By crank, do you mean crankcase, or crankshaft?

I only can see it when I take the to end off
Where are you seeing it?

when I check the oil its the right amount
What oil are you checking?

And the carbrator is over flowing it's not going into the bowl
It must be going into the float bowl, that is where fuel goes after it has entered the carb.

that baring for the piston
Are we speaking of the wrist pin bearing, big end bearing or crankshaft bearing?

Okay one thing the piston is hitting the head of the cylinder and the guy didnt change the bearing for the piston is that why it's doing that .
To my knowledge the wrist pin bearing has no relation to piston height.

That why I rather do my own work
If you wrench as well as you explain, I do not see this motor running well soon!

And the gas isn't in the oil but on the top of the crank in it came out of the exsust what causing this
Is the cylinder flooding due to a dirty or worn needle and seat, causing hydro locking, fooling you into thinking that the piston is hitting the head?

Gee I need a stiff drink.

I thought I drank something funny cuz I was seeing this rainbow on my screen lol man
 
3 in the morning, can't sleep, what better to do but amuse myself and maybe get to the bottom of things to help this poor guy.
 
Well I havent had time to work on and this guy told me all this ik how to work on bike I just don't understand why this bikes give me so many weird probs . I think the carb is causing all this because it was corroded I got most off