yz125 not running right

I got my cylinder bored, put a new piston in, and installed a brand new carb and my bikes not running right. I messed around with it quite a bit and it will only run for a bit with the choke on. When I turn the choke off it will only run at really high rpms. Any ideas? 

I got my cylinder bored, put a new piston in, and installed a brand new carb and my bikes not running right. I messed around with it quite a bit and it will only run for a bit with the choke on. When I turn the choke off it will only run at really high rpms. Any ideas? 

Check power valve. it could need to be adjusted or you may need a new one. Depending on the year, the powervalve can be attached to the cylinder, so if it was rebored, whoever did it may have messed up the adjustment or broken the powervalve completely. Give it a look. check your manual to see how its supposed to be adjusted and give it a shot. if it doesn't work at least you can eliminate your one possibility.

Maybe just a jetting adjustment needed, that could be why it only runs at higher rpms

I got my cylinder bored, put a new piston in,

 

 

Did you get the cyclinder re-plated ore bored? Was it matched to the piston or did you buy the piston after.

 

 

and installed a brand new carb and my bikes not running right.  

 

Brand new as in new and correct, or new as in new used, new as in rebuilt?

 

 

I messed around with it quite a bit and it will only run for a bit with the choke on

Choke on only is probably pilot jet plugged.

 

What year is it? 

Did you get the cyclinder re-plated ore bored? Was it matched to the piston or did you buy the piston after.

 

 

 

Brand new as in new and correct, or new as in new used, new as in rebuilt?

 

 

Choke on only is probably pilot jet plugged.

 

What year is it? 

Got it bored at a shop and they ordered a piston that matched the bore.  The carb is a new remake of the original carb, bikes a 76'. Ill try cleaning out the jets but it shouldn't be dirty since its brand new. Thanks for the reply.

Check power valve. it could need to be adjusted or you may need a new one. Depending on the year, the powervalve can be attached to the cylinder, so if it was rebored, whoever did it may have messed up the adjustment or broken the powervalve completely. Give it a look. check your manual to see how its supposed to be adjusted and give it a shot. if it doesn't work at least you can eliminate your one possibility.

Thanks for the reply. I don't think it has a power valve because it looks like power valves weren't introduced to the yz's until the early 80's.

Later years (1980+ s to current) of YZ are niklasit coated so boring is not really an option. 

Yep, being a 76 it is steel sleeve, and hopefully the machine shop was good and pitched it to the correct size.  Drop pet cock check filter on it, make sure float is set to correct height. 

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