Dyno lifting Y-2 Cylinder

Today I tested the lifted Y-2 cylinder, this all was mend to try to reach the same power outcome like the Y-1 cylinder.
I raised the Y-2 cylinder with a 1,5mm base gasket and machine the head to a 12,4cc with a squish from 0,9mm on my research engine
When I mounted the set on my track bike it turnout to be +/- 12,3cc with a 0,85 squish.

Her is the bike ready for its firsts runs with lifted Y-2 cylinder

The runs where pretty constant between 25,2 and 25,5HP
Here you have four runs

To give a better view, here is one off the best runs
25,5HP at 11043rpm

Here you have two runs
Y-2 cylinder with stock base gasket and a 0,9mm squish (24,7hp) vs Y-2 cylinder with 1,5mm base gasket and 0,85mm squish (25,5hp)

Here you have the lifted Y-2 vs the average runs from a Y-1 cylinder.
Y-2 with 25,5HP and the Y-1 with 25,8HP

On one off the last runs coolant came looking for me, first thought I blow up the head gasket.
But it turns out it was a lose bold from the cooling circuit off the carb (with I looped)

Looking back this mode gives you about 0,8HP witch brings it about the same level as a Y-1 cylinder (in the same setup)
Still a lot off work needs to be done to reach the 30HP, but I'm afraid it can't be done without porting the cylinder properly.

I'm not giving up yet, like to experiment with the spacers one more time (perhaps I missed a step) and I will change the reedblock to see if that will bring me something to