Help!

[yfm250rider]

just got done rebuilding my trx motor new piston and cleaned up the head. had problems starting it was bad gas cleaned the carb and flushe it out. now it is hard to start and the pipe glows red within minutes of running. didnt change anything jets filter pipe are all the same. why the hell is my bike running so lean??

[xcracer416]

how much did you clean up the head? is the timing right? valves in spec?

[yfm250rider]

cleaned the grime off the valves cleaned the black off the cylinder head checked timing twice thats spot on shims and springs are the same bike was running perfect before i rebuilt it

[xcracer416]

i would recheck your intake boots infront and behind the carb. recheck your valves also. if you didnt change the compression ratio then look for the obvious

[fomospede]

what was temp when it ran good and what is temp now??

also maybe it is making more compression now ?
even though you may have bought the same compression piston they do vary some
id check intake with spray if fine rejett and ride it no big deal

[yfm250rider]

my ran spot on it was stock the never even had the fan kick on bought a wiseco piston same comp and theres no way it has more compression need to make sure the air boots are tight and way an exhaust leak is causing it?? put i new copper crush ring in the head