This is why you always do a compression check brand new, without even firing the bike.
I'd bet the pistons are fine....one of a few things:
1. Piston to wall clearance is out of spec
2. The domes aren't the right size (larger than 17cc, like a 21 or 22cc) In that case...it's fine
3. BOTH compression testers are wrong, or you did the test incorrectly...
While I agree 17cc should need race fuel, 110 all the way....I would find it very hard to believe you damaged both pistons THE SAME and it's equally as low on both...
I'm leaning heavily towards 2...with a little 3 thrown in for good measure.
.055 is a little big for a small bore motor, but...it should produce a LOT more than 135 if it were 17cc domes.
I run .055 in my motor, but I also have a bigger bore, more timing, stroked crank and I run alky on an aftermarket cylinder...with 180 to 185PSI on 20cc domes.
Before you worry too much, drain the coolant by removing the lower rad hose from the water pump cover, and pull the head off.
There will be an arrow on top the pistons, they need to be pointing toward the exhaust.