I remember learning in training how the Moster 185 could be difficult to start and so when it came to actually starting it myself for the first time it wasn’t a big surprise when it took 5 pulls. After that the same engine typically started in just one or two pulls.
So then when I had my own new machine I expected something similar. It wasn’t, not at all.
Combustion occurs when you have 3 things in adequate amounts: heat, oxygen, and fuel. It’s the fire triangle. If your engine will not run you will need to determine which of the three is/are lacking.
In my case it was oxygen. I was too newb to know the difference between foam that filters and foam that is meant to plug a hole. Some engines come with a hotdog shaped piece of foam in the intake port of the airbox, presumably to keep fumes in and critters out. This foam if left in place would not allow a start.
Troubleshooting this as a newb was a long but enlightening process. I tried 3 different spark plugs with no change in symptoms. I tried many different priming quantities with still no positive results except when I tried to start with no prime and full throttle. There I could get a sputter, hope. In fact, when the air was cold I could get double and triple sputters. I’m thinking at this point this engine wants more air. I removed the airbox and tried. It started with the first pull! I then tried the airbox without the questionable foam plug. Again, it started on first pull. It was soon after this that friends confirmed that this foam was not part of the filtration system. Ha!
Maybe this anecdote will save someone else some time troubleshooting. If not, maybe it’ll provide a chuckle. Either way, have a safe flight.
It always comes back to the basics. Spark, Fuel, and Air! I have a Nitro 200, and the stock carb base gasket is made of paper. Well, over the last two years it started to deteriorate, and air would seep into it under the carb into the motor. This caused it hard to start, and I had to richen it because the extra air was making it lean. Basic maintenance can go a long way, after I replaced the gasket it fires right up now first time every time.