Saito FA-125 A Look Inside

[@pontiacdriver999]

I picked up two of these for $250. Both only had like 4 or 5 tanks on it. Awesome engine. I put one on my Sig 1/4 Cub and the other one is just sitting on the bench. Not sure what I want to do with it yet......

[@dmrcflyr2]

That was my first experience with a 125. It is one hell of an engine. But most all Saito's are. I think I prefer the older FA-120DP that I have. I have also run and have videos of the original FA-120 'Fat Head' as I call it. I have just rebuilt another Fat head but have not run it since or posted any of the videos of it yet.

[@pontiacdriver999]

Yeah, so far it's an awesome engine from what I can tell. Starts pretty easy but since its still being broken in I haven't had it over 4k for more than a few seconds. Haven't flow the plane yet. Hopefully I'll maiden it this weekend.

[@aerofan778]

Did you ever find out what gas he ran? And do happen to remember what glow plug? As usual. Awesome video David. You’ve videos have taught me a lot. Ty

[@dmrcflyr2]

I do not recall asking what fuel he ran in this engine. This video is from over 1 year ago and I would not remember anyway.

[@billkourtis2698]

are the valves different sizes ; I am rebuildind an old 125a . Waiting for a valve set and wander where they go . i think intake is bigger , correct ;

[@dmrcflyr2]

I think it will be pretty easy to tell which valve goes where when the engine is apart if they are different sizes. If they happen to be the same size, then it does not matter, right?

[@glaucopimenta]

Great, David! You really have great expertise on 4 stroke engine!!! Congrats!!! What about the Saito FG21 4-Strokes gasoline engine? Can you make a run up Saito FG21 engine test review? Cheers!!!

[@dmrcflyr2]

I do not run gasoline engines. However I will run any engine that is provided to me.

[@glaucopimenta]

David McIntire all right! Because I am looking for a Saito FG-21 4-Stroke engine to put in my Super Decathlon 1.20 aircraft model. The Saito FG-21 sound looks great, but I know gasoline engines produces more heat and less power than the equivallent glow engines. Gas engine operations should be more delicated, yet? Ok. I will waiting for your possible 4-stroke gas engine test review. Thanks!

[@glaucopimenta]

Bunnyshooter 223 , all right! Really, gas engines are very fuel economic! And a cheap fuel. Ignition start make it more reliable at idle situation. I did not knows gas engines presents low weighy-to-power ratio than equivallent glow engines. It is sure?

[@glaucopimenta]

Bunnyshooter 223 Now I understood your explanations. So, gas engines are much weighter and gets less power than the same displacement glow engines, yet? The gas engines produces much more vibrations and heat! My doubt... Gas engines are better in large aircraft models that needs large displacements (up to 50cc)?

[@glaucopimenta]

Bunnyshooter 223 Really! As you said, I did read that all stroke and displacement type gas engines produces more heat and vibrations. I have seems here in Brazil, Franca city (very hot now in summer 😅), air modelers flew gas engines without it break-in on ground! They break-in gas engines on flight, leaving needle valve at rich misture and applying just 50~60% throtle level. About nitro... Can I put 5% nitromethane in the gas fuel mixture without problems? It's true nitro helps gas engine to run more cooler?