I just used my Snap On Compression Tester on my DT2 and don't believe the reading's correct. I've used it on cars before without issue.

I've looked at the piston and rings through the exhaust port and from there they look okay. I had the head off, de-carboned it and the top of the piston, not a lot of carbon; 2,200 mile bike. I installed a new Head gasket. Top of the piston looked good, so did the cylinder wall.

Cold engine, screwed the tester in, throttle wide open and started kicking her over. 225psi?

In going through threads/posts in the search feature I'm seeing folks getting 130ish psi. My Clymer Manual states 100-150psi.

Any thoughts?

No sure, but wish mine had that much, or might with an mx high comp head--not sure, but just sounds wrong.

Are you sure you're not reading the kpa scale?

In my experience and opinion compression testing is worthless on these bikes unless you really know your gauge, technique, and bike.  The smaller your engine, the worse. 

My Snap On gauge reads the lowest by far of the three gauges I have.  On a car, they all read very close. 

Nope, it was psi

 

How 'bout this?
There was still some 2 stroke oil in the Auto Lube pump, and it was being sprayed into the combustion chamber while I was kicking her over. That, plus the little bit of oil I'd coated the cylinder wall with when I had the head off, causing the excessively high reading?

Has this bike been run recently?  If not, my guess is she has a belly full of oil from autolube check valve seeping?

Second guess is what RT325 said...  someone might have installed an MX head on a stock enduro cylinder. 

I don’t believe the bike has run since ‘95. The pervious owner said nothing had been done to the bike so I’m pretty sure it’s the OEM head. Would starting it with excess auto lube oil in it cause a problem (like blowing out the crank seals) or would it just blow out the end of the pipe?

Excessive oil in bottom end can push out a crank seal.  Even before you start it.  Probably won’t start if crankcase has excessive liquid. 

Ah, not run since "95. Any oil left in the tank. Push it around with ignition 'off' with plug out & exhaust off--see if it makes a mess--then try starting it but bring the revs up very slowly not a big handful straight off while it gets cleared out from an extended hibernation. That's providing the right side crank seal is in place but they hang on pretty good compared to the smaller motors. Never heard of an early 250-360 blowing one out but could yet to be enlightened.

I had one the same--& same color in "72. Loved that bike.
Ha--found a video of mine. Drag it to 5-12 where i drop it but looks like i get it right the next lap haha. Only running the std  trail "19 in the front. Motor on methanol with a DT1 GYT kit high comp head but std cylinder--went good too. Must've had the chamber exhaust too from my DT1 race kit from "70. All a blur nowdays haha. Youtube can slow the speed as runs a bit fast. Just playing the start i hear Alan McLaren say Novermber "71 so we must've got the "72's early. We were waiting for the DT2MX proper out of the crate MX bike which came later in "72. Anyway, enough bull--t.