Motorcycle Repair: cylinder bores, cylinder bores, stock cams

Question
hi, i have a 05 HD softail fxst,iam haveing the stock barrels bored to 3.875 (95ci)and using wiseco pistons, swapping out the stock cams for the andrews 37n cams,also going to use python 3 exhaust,yes the engine is fuel injected that will be up graded also with a fuel pak, iam hopeing when all is done i should be in the area of 95-100hp range at the rear wheel, ( i want to tell my brother with the 103ci roadking how do you like me now? ha ha)i have talked with some of my bike brothers on this thet give me thumbs up on it but they think boring the stock barrels to the 3.875 is a bit extreme an the walls would be to thin, the guy doing the work says no, and so do a few other HD SHOPS they say the walls will be fine. what do you think on this? to bore or not to bore.

Answer
Ken,

-the problem is not the thin walls, it is the
quality of the bore job that is important.

-More often what happens is the cylinders are not
bored straight and the taper makes bad fitting
pistons and rings. The excess blowby burns
oil off the cylinder walls and then the heat
and friction warps the thin cylinder causing
more sealing problems.

-You can see the original problem is the poor
boring job not the thin cylinder.

-my advice would be to study up on boring machines
and find someone that is well experienced.

-if the boring is done poorly what you have
is an engine that is worn out before
you even run it.

-I have seen cylinders bored so bad that the engine
smoked like mad right from new.
This would of course mean all the power
you were hoping for will go down the
tailpipe.