Probably less than a hour if we are talking about a 3400 and a LRB piston. Now if you are talking about a poulan 4000 with chrome bore and a LRB piston i have one that has 23 tanks of fuel and it looks new. Difference is the 3400 piston should be chrome plated and it's not. The 4000 has the chrome plated bore and needs a plain unplated piston. 3700 is the same as 4000 and 3800 is the same as 3400.