mud runners rebuild

ok where do yall think i should start jetting at no airbox lid full dg and ported premix 20/1
and 32/1 and all the stuff listed above
 
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ok iv got a question on the extra bottomend iv got i cant get the nut that holds a gear onto the crank any ideas on how to get it off iv tried pb blaster and krol oil
 
whats the penny trick and iv tried a impact driver and i dont have a breaker bar but i might have some 1 1/2 round tubing that might work