12mm thread. I would not use the rubber tipped testers, they are cheap and will not seal 100% which will give you inaccurate readings. Its hard to hold against something that will be pushing back 150 psi.
Did you check with the throttle wide open? make sure the battery is fresh and cranks over fast. Have you verified valve clearance yet? 170psi is high, there wont be many of these bikes that will ever show that high.
1 TBS is a lot of oil for the smallish bore, you may have inadvertently givin yourself a false increase by that amount of oil, that much could effectivly bump compression. You want just enough to wet and seal the rings not reduce chamber volume.