Started to break in a brand new saito 180 today and having some difficulty. Using 30% nitro w/ 20% oil after several attempts ruling out the fuel lines, filter, on board glow and the OS F plug it finally went without any changes. I have the needle turned out 4.5 times and it ran for roughly 7 minutes at no higher then 4000 RPM's then it stopped. It would start but never for more a few seconds.
Again ruled out all of the above noted possible issues again. What should I look for? looking for help. Note the break-in was with a apc 16X8 prop.

I would look at the easiest thing first and change the glow plug. If that does'nt do anything, I would look for something, fuzz, or crud to be stuck in the needle valve assy. causing a blockage.

break in is real hard on glow plugs sometimes, so it is not uncommon to have to change one or two.

Why are you using 30 percent nitro to break one in on? I would try some 10 percent fuel with a new glow plug. Mine has always started real easy on the same fuel I fly my 2 strokes on.

I've had two 180's and they have both been bears at first. I'd cut down the brew to 15%/18%. The other thing I'd switch up is the prop. Get a heavy as hell APC 18X6 and let her rip. Make sure the barrel holder screw in the carb is in good shape and not snapped off... Me first one did that and it took me a while to figure it out... The barrel shouldn't move much in and out of the carb body... Duhh...
Other than that expect to put about 5 gallons through it before it really runs well. Once it's fully broke in it will idle and transition great.

I will try 15% and look at the areas noted

The advice above is excellent. Mine was a bit contrary at first but once broken in it runs great. It doesn't make as much power on 15% but does seem to run smoother especially at idle. I would check for an obstruction in the needle valve assy as rcdude mentioned. I have had to completely disassemble the carb to get mine cleared before. Sometimes the little piece of trash doesn't want to wash out any other way and if it fires and then instantly dies that's a strong possibility. The other possibility is the fuel tank is too low. If the fuel drains back out of the line after the initial prime the tank may be too low causing the engine to die before the fuel makes it back up to the carb. Good luck.

Want to thank all for their responses and insight. After checking out the needle valve, F-plug, fuel lines etc, etc, etc it came down to the on board glow system. I disconnected and used a starter with success of two full tanks without issue. It is obvious 4.5 turns out is way to rich but that will be resolved soon with a few more break-in runs.
Again thank you for the insight and help. Good stuff