Nelson,
I don't recommend hand starting the YS motors. They have very high power and as a result can get a little bite that can take your arm off. I have been flying YS motors for a very long time and I use a starter. Multiple reasons and the least of which is I have all 10 fingers and all 11 toes!
The small clicking noise you are hearing is probably the tappets on the valves and or the cam gear followers. This can be common when the motor is dry. Pull the valve cover off and check the tappet clearances. They should be about 2-3 thousands of an inch.
If they are extremely wide gaps this could be the clicks...You say it sounds like its down near the crank this is most likely the followers that ride on the cam. As they pass over the lobes of the cam sometimes they will click down onto the back side of the lobes. This usually happens when the motors set a while and the oil such is a little thick inside. It will go away after you run it. If the motor has set for a long time then run it for a a tank or two without touching the regulator. Chances are its a little gummed up with thicker oil and will clear out as the motor heats up and runs. Lots of guys let their motors set all winter then come out in spring and spend 4 days trying to dial the needles in....When they were fine to begin with...the motor just got thick oil in all the little nooks and crannies. In the YS pressure system there are lots of places a little dirt or thick oil will make a engine run poorly.
Next thing plumbing is important with the check valve and all. Go to the YS Performance website for instructions on how to hook up the plumbing, and how to set the needles. Blow through the check valve perhaps run fuel back and forth through it to clean out any oily gunk. This will keep the check valve from working properly and will cause problems with getting the motor to run.
Always remember the YS pressure system pressurizes the tank. So you need to make sure you have a good quality tank. Always release the pressure first before unhooking the fill lines. Go to Central Hobbies website and they have a good drawing of how to hook up the lines with T's to get the vent line open and keep you from hooking and unhooking to the motor each time you fuel.
http://www.centralhobbies.com/instructional/lines.html
This shows the setup for the FZ style motors. This is the same for the 120SF, 120NC, 120AC (sort of it has more lines and such), and 120SC as well. The 140's changed a little then came back to a similar setup.
The regulator has moving parts but they move with pressures and have silicone parts so you won't hear anything out of it.
I would stick some good fuel in it. Cool Power 30% heli fuel is an excellent choice and will make it sing. Maybe a 16-8 prop maybe a 15-10 depending on your needs. And use a starter! These things can kick back. Now after you get the motor setup and all is working great...Sometimes a talented snap of the finger can start them...But I stopped doing that years ago. My Talented finger worked half the time and a starter was always on hand anyways. By no means flip the prop like you or I would an OS 46....These higher compression higher output motors will often backfire if they get a little wet and they have 3+hp to take off your digits.
I always recommend using high nitro in 4 strokes. They run and idle better on it. Makes the mixture setting less sensitive and critical. I would say always run 20% or more nitro. They will run on 15% but it will not be as easy to setup or make as much power. Saito 4 strokes are the same way they like nitro.
Next thing on fuel use only a synthetic oil like Cool Power. Don't use castor. Really the synthetics are what you need. There are lots of little passages and such that fuel and pressure pass through. You don't want these to gum up with castor. Omega is the castor version of Cool Power. While some guys run it in their motors I stay very far away from it. I probably put 600+ flights on some of my YS motors every year. There have even been times I was putting 1000 flights year on my model. Synthetic oils are the best for this application no doubt.
Next thing OS #F or YS glow plug. Central Hobbies has about the best price on these like $5.30 each.
Troy Newman
-YS Performance