Chainsaw Repair

Couple more points .You obviously have not really looked at the design because this is not a removable cylinder type engine like a Stihl .

By and large all McCullochs are cast as a block .The reed valve models it's all one assembly and the 10 series and Mini Macs it's a clam shell design .There is no swapping cylinders although on the cast iron liner types they can be over bored but you'd have 6 times as much as the saw is worth to have it done .

Facts : A 250 was made basically in the early 60's when the transition was from heavy old gear drives that weighed a ton to lighter direct drive saws .Now they will cut no doubt about that and can be modified .However is the cost and frustration worth it ?

An 82 CC J-D branded saw will run at RPM's that would shake that old reed valver apart .It produces it's power like a Chevy 350 at RPM while a reeder reachs peak ,like a Ford 390 at lower RPM .

If you  want a Mac that could stand up to the BIL's saw for speed get an 850,805, SP 81 .I'm not trying to be pessimistic  just the facts as I see them .