Which is better to do? Getting a honing tool and using a power drill to hone the cylinders or getting a machine shop to do it. Has anybody ever messed up the cylinders by using a power drill? How much material does it take off?

 

You can do VERY minor surface cleanup with a flex hone, but any sort of alignment honing or real material removal must be done on a suitable machine. Bore dimensions and alignment are a high precision matter.

 

I just got a B18a block that has been sitting outside for a good while. The only rusted part of the block are the cylinders. Are they still good? I was thinking about getting it resleeved.

 

Take some steel wool to it to see how well it cleans up. You can hone by hand. Some very knowledgeable peopl I know massage the cylinders by hand with sand paper and this works really well.

But if you don't mind spending $25-$35 then just let a machine shop do it and make sure they do the last step with 400 grit stones with light pressure. Most modern rings like it smooth.