I wear leather gloves when I start engines, and I wear leather shoes around my wife's horses.  I do both for the same reasons -- so that when things go wrong, it's easy to collect all the pieces to take the emergency room!

I learned a tip from David Gierke's book, and have used it with great success, is that if you have an ABC engine that's really tight, heat the head up good and hot with a heat gun -- this makes the cylinder expand, and gives you a chance to start it.  Then when it's running, you can do the usual ABC engine break in thing.

Granted, I've only used this tip once, for my one and only ABC engine, but it sure worked well that one time!

Randy,

Tim is correct about using pre-heat to loosen the sleeve/piston fit.  I've been starting these very tight R/C engines for years and have never been able to hand start a new engine.  The tight tolerance will not let the engine rotate thru the second revolution.  I would get an old spinner and use a starter.  Just be careful not to spin the cold/dry engine too much.  The piston/sleeve will wear pretty fast until the head temp comes up.  Also, do not run the engine rich when tight.  The temp must come up to expand the sleeve.  Many new guys have ruined their new R/C engines by breaking them in too rich.  Save your fingers, use a heat gun and starter my friend.  And be prepared for the prop nut to pop loose during the first few starts.  Be cautious about that!

Paul

Randy

I'm an r/c pylon racer.  Start these things all the time.
Assuming it isn't damaged from dry flipping do the following.
Put some oil in intake and down plug hole
Turn it over not flip just pull it through about 20 times with plug out.
On test stand set it up to run
Put spinner hub or old spinner on it. Make sure prop is tight
When ready to start
Before putting glow driver on it do following
Finger over muffler outlet or intake
Spin starter up to max
With starter running full tilt push hard against spinner / spinner nut
Engine will spin and draw fuel due to finger over muffler outlet or intake
We use muffler so just finger over muffler outlet.
After fuel spraying out intake due to plugged muffler stop
Turn prop backwards until you feel compression.
Glow driver on
Spin up starter and push hard against spinner / spinner nut.
The trick is hitting the spinner with the starter at full song.
After you have run it a while it will get easier.
If all else fails try warming cyl however I’ve never had to do it and we use engines that are very very tight
If it floods remove plug and hit it with starter
No damage to engine when hitting it with the starter because of bearings
Takes much longer to explain than to do

Barry

Randy
When I was in R/C we had to loosen the plug on the Rossi .80 ducted fan engines to reduce compression just for starting and then tighten up the plug after it started.  Sounds crazy but it worked.  Don't know if your problem is compression, pinch or a combination of both.  The spin up of the starter is a good way to overcome compression I use this method for bump starting my larger diesel engines. 
Andy

Randy:
We use the Sullivan dynatron high torque starter with a soft neoprene cone with a 12 V gel cell strapped to it or a bunch of C size NiCad’s.  Also alum spinner or big spinner hub which helps with slipping.
Try heating the cyl with a hair dryer or heat gun see if that helps. (watch the heat gun, mine will actually melt alum).
When our engines are new, even  after having been run a few times, they squeak and are so hard to turn over you think it would damage the piston.  (I hurt one once with a new p/l  by trying to start it without lubing it first).   
As someone said you can also loosen the plug.  It might work better but I really don’t think it’s a good idea.

Barry

If starting a new one is that bad, I would look for one of the R/C gear reduction starters.  You can probably find one at a swap meet for chump change, and it should be able to tackle the tightest of motors.  My cheapie magnum copy of the kavan starter handles 60 motors with ease, a "real" gear starter should be able to turn over anything you might get your hands on with no trouble.

The best way is to warm the head with a heat gun, as mentioned by David Gierke or even with an iron solder, just touching the head the time enough to warm it.  These methods are easier and softer and don’t cause the risk to broken or damage a con rod, the engine or yourself. Then you start the engine by hand flipping with a safety stick or with a starter (you can use a spinner with the propeller). I have already tested them, more than one time in ABC engines, and they always worked well.

Luiz