throtle spring (rejet ?)

[cujion]

do you need to rejet when you change the throtle spring . Just purchased a ligter spring for m,y YFZ . when i was done was acting like it was running lean and the pipes tured red after a couple mins .

[GPracer2500]

AFAIK, the strength of the return spring doesn't impact fuel metering.

Maybe an air leak? Make sure the carb boots are in place and secure.

[cujion]

thanks for the info after thinking about it i figured it might be an air leak or maybe something fell in there and is blocking one of the jets i'll take it apart tomarow and giuve it a good cleaning