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Mar 29, 2014, 12:23 PM
Cat Man
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The break-in's continue. Saito, OS, Magnum

I ran and continued the break-in of some engines today.

First was The Little Gem, Magnum FS-30. This little engine continues to impress me. As I mentioned in an earlier post, as the compression increases the difficulty in starting decreases. It took a whopping 6 flips to get it running today. Of course the key to hand starting a four stroke engine is properly priming it. Not all engines prime quite the same.

I always start with the tried and true full throttle, cover the carb opening, and turn the prop over until fuel comes out of the carb. Close the throttle and turn the prop over a few more times. Although this engine draws fuel in easily using this method getting it into the intake is another matter. This engine needs a bit of fuel shot into the head through the glow plug hole. Once that is done it fires right up. I am running a 10x6 APC on this engine and it posted 8300RPM at WOT and ticked over nicely at 3100 PRM at idle. I did begin to adjust the low speed needle; I closed it about 1/4 turn. Transition is from idle to full throttle is nice as long as I don't really advance it too fast. I deem this engine ready for mounting into the Waco 30 it came with.

Saito 80 GK
This engine is on about the 4th tank. I inadvertently installed the MA 14x6 on it today instead of the 13x6; I did not notice this until after the run. As mentioned above about priming, this engine does NOT suck fuel up into the carb very well using my normal method. I have seen this on other Saito's although most suck it up pretty well. This engine also requires a bit of fuel shot in through the glow plug hole for prime. Once that is done it is a 1 flip starter. This engine is a freaking beast! It seems almost as powerful as the 91. I had it turning the 14x6 at 8300 RPM at WOT and ticking over at 2800 RPM at idle. I tried to richen this a bit from the 8300 and when it hit about 7500 RPM it was literally spitting fuel out of the carb; so I leaned it out to the 8300 setting again. I LOVE this engine. Aside from the priming issue this thing rocks! Of course pretty much all Saito's do, but....

OS FS-90 #2
I'm not really considering this continued break-in but just running. Long ago in more of my hey day in building and flying, I used to buy OS engines almost exclusively, I'm talking back in the early 90's. In the last 10 years I really have not purchased too many OS engines. I think they are over priced and over rated. HOWEVER, this old FS-90 really has a spot in my heart. Maybe that is why I have had 3 in the last year. It just oozes quality. It looks, feels, starts, and runs with quality. It primes easily using my preferred method, starts on about the 3rd flip every time and runs like a champ. It there was one crtiticism I can find with this and my previous FS-90 is the needle valve. It seems like just barely touching it, not turning it, affects the RPM of the engine. It is quite sensitive when you do turn it. It takes very small adjustments to make large changines in RPM. I have not started the 3rd NIB 90 as yet, but I will be juding the needle valve on it closely. I need to see if this is a design thing or if the previous 2 engines were man handled on the needle valve.

It easily turned the same 14x6 prop at 8300 RPM and ticked over quite happily at 2500 RPM at idle. Transition is very nice. Just a quality engine all around.

I also measure thrust of my engines in a very unscientific way. I stand behind the engine while running and just feel the prop wash. I can feel it and get a pretty good idea of how well it will pull a plane of a certain size. Like I said, very unscientific but I have been doing it for years and have never had an underpowered plane. I truly think this OS could easily pull a 10-11lb plane around quite nicely. So installing it in a warbird is not out of the question, but it seems like it would be a bit over over kill for a SIG Astro Hog weighing in at 7-8 lbs. My Enya 80 or the Saito 80 would be a better match for that airplane.
Last edited by dmrcflyr2; Mar 29, 2014 at 02:57 PM.
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