Chainsaw Repair

You still need a set of micrometers to measure the snap gauge. Still these are prone to error and the measurement process is arduous. 

Industry standard is a dial bore gauge (still need mics). There are some pretty decent cheap sets out there that do 2-6" with 0.0005" increments.

http://www.ebay.com/itm/Igaging-Engine-Cylinder-Dial-Indicator-Bore-Gauge-2-6-/141472741994?pt=LH_DefaultDomain_0&hash=item20f06eba6a

Or extender series stuff which has an extra head that goes done to 1.4".

http://www.ebay.com/itm/Fowler-Cylinder-Dial-Bore-Gage-1-4-to-6-/111608389384?hash=item19fc60df08&item=111608389384&pt=Motors_Automotive_Tools&vxp=mtr

Or you can get more precise ones in 0.0001" increments.

http://www.ebay.com/itm/2-6-x-0-0001-Dial-Bore-Gauge-Set-Brand-New-EE20-1006-/161510210358?pt=LH_DefaultDomain_2&hash=item259ac23b36

I personally have a 1.4-6" set with a digital gauge that reads in 0.00005" increments. It's way overkill.

I've got them from about 1/4" up to 6" .I've got micrometers up to 8" mostly Starett .One set ,1-2"came from England with my great grandfather circa1900 .

I have the setup like in the first post as well as the mikes

i agree with all of you and the bore indicators are great for out of round or dished out bores. I do want to challenge you to check your micrometer against a newish decent quality electronic caliper. I did  not believe in them till I had to use a 36 inch pair for a year and get parts through quality control. Keep yourself honest with a mic once in a while but once you get used to the feel of the caliper it should be easy to get accurate results from a 2 to 3 inch T  gauge.

A caliper, digital or not, will never replace a micrometer. Because of the slide action and the lever arm you have on it from the measurement surface it's too easy to blow the reading a few thousands with little pressure difference on the thumb wheel. Even though the digital calipers can read in 1/2 thousands there precision is around 1.5 thousands. Measure the same part 10 times with your eyes closed and see how much your measurements vary, you'll be surprised.

Snap gauges are only used in cases where a dial bore gauge cannot as they are much more prone to imprecision from human error since there are two stages in the measurement left to feel of the user.

If you use a dial bore gauge you don't need expensive micrometers, just solid ones. As you just use them to transfer the piston diameter to the bore gauge, then you take a clearance measurement.