Saito FA-150S Serious Detonation
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- เผยแพร่เมื่อ 14 ต.ค. 2024
- A run where I overly lean the engine and it detonates not once but twice. Xoar 17x8 prop, Saito P2 plug, and 10% nitro fuel.
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I remember when the early 4 strokes started appearing at the flying field, before OS started fitting the locking nuts, that prop spitting was a common problem. Very frightening, especially on a 150 size motor. Great video David, thank you.
nice video Dave!! from previous experience, saito 180, that threw props to the point of donating it to the nearest bin, an old hand commented that we should replace the saito plug with an os-F, problem solved after that. we were gobsmacked!
Thanks David! In my very short but growing experience, I have heard OF detonation and knocking, but never experienced it firsthand!
Hi Dave, I have one of these engines. Timing is 'sharp' and mine was cranky too. A thick cylinder gasket tamed it. I'll make some videos when work allows showing the difference. In any case, please keep up the wonderful work!
We had the same problem with an OS FS-95V running a wooden prop it kept knocking the prop was replaced with a plastic one,it hasn't missed a beat since.nice video 😎
Totally agree. I think 4 stroke engines are more susceptible to blighting back hard in lean conditions compare to two strokes and give you a nasty prop spitting moment.
Great run though and a great lesson to be gentle on the mixture on these engines especially a 150!
I'm a simple man. I see Dave, I click thumbs up!
Glow ignition timing is controlled majorly by compression ratio and minorly by nitro %, heat range of glow plug. A colder heat range glow plug or lower nitro would nip that detonation in the bud most likely.
I also suspect it's a bit overpropped. 7500 at full blast is a bit on the low side. My 125GK will turn 9500 quite happily, makes great power there.
Thanks for the video and information. I also have a 150s, although never experienced detonation. I will be more careful when adjusting the needle in the future! Cheers.
That is why it’s very important some of these 4 stroke engines you have to do needle about 3-4 clicks at a time 1/8th of turn when leaning.
I have a Saito 125 that doesn't like to be too lean as it will do the same thing. It seems mine likes to run on the slightly rich side.
The first gen Saito 150 is the only model airplane engine I own that actually scares me. I have several dozen gas and glow engines. Like the original OS FS-120 with separate rocker covers, it has too much compression but it's on steroids compared to the FS-120. The OS can be tamed by using a fuel for big Super Tigres that only has 12% oil. The Saito, IMO, needs a much thicker gasket between the crankcase and cylinder to reduce the compression ratio. When I put mine on its next airframe it will be running a thicker gasket, no nitromethane fuel and a CH Ignition spark conversion.
Maybe this versión has a little higher compression than other 150 versions, and/or sligtly smaller combustion chamber, but it's very sensitive high speed needle adjustment near peak rpm, that was a really great example on how a knocking engine sounds like.
my fa120,and fa180,dont have that issue but my fa150,does. it seems to be noticeable higher in compression the the other 2. it reminds me of that damn fs80.
Mr. David,. I'm 64 yo AirForce, 13 years Elec. Rc planes, have 5 Hand me down glows to Tinker with,. Hope your Doing well,;Glad to see a bit of The " Nitro, gas Hobby. Enjoy Squireel, humminbird, nature Content. Regards.
J. Shelnutt Alabama USA
Have another drink...
@@cpncme273 Your Mother Must be So Proud,. Get back on your Meds.
Had an old Saito FA-80 that did the same thing: complained, spit props, and backfired anytime I got to greedy leaning it. Chasing that last 100rpm sometimes is just more trouble that flying how it is. :)
Hi Dave. I’ve noticed that sometimes you start the engine by turning the prop in the opposite direction? Am I seeing that correctly and if so why?
With four stroke engines, particularly large ones you can start it either way. it is often referred to as bump starting. It can be a means of avoiding getting bit by the prop should it detonate on startup. For more information and opinions on the method, I recommend searching on your favorite RC forum.
Interesting. I will look it up. Thanks
Thanks for Sharon Dave I had a OS 91 surpass do the same thing if you tried to lean it
I am bout to get this motor from a friend. I'm still on the fence.
Why? The 150S is one of the greatest Saito engines of all time.
I used to do R/C models till the fuel price went up from £11 a Lt to £45 a Lt then I gave it up
when you started it by hand you turned the prop backwards thats why it didnt run correctly The electric starter ran it in the correct direction CCW facing prop
Back starting the engine is a common way of starting engines. That is NOT why it didn’t run correctly. Do some research on starting engines before you comment please.
th-cam.com/video/2g1QlnWyDn8/w-d-xo.htmlsi=-EQZLFLAPsCk0y7e&t=264
th-cam.com/video/FHi3i1nEV-8/w-d-xo.htmlsi=1LeHVhFm6gLGkB7b&t=169
Are you saying at 2:19 when you started the engine backwards thats a common procedure ? Could you please elaborate? Or did you just flip it backwards and then it ran in the correct direction? Also please let me know where i could do some research and find out about this procedure?
@@anthonyiannone7618 Well there are RC forums you can visit that will provide all sorts of information such as RCGroups or RCUnverse. I really do not have the time to go into discussing priming a four stroke engine, the causes of detonation, etc. Detonation has more to do with the compression ratio of the engine, over priming, and then also running an engine too lean. It is a multi faceted topic. The internet has plenty of information for you should you desire to research it more. I am not here in the capacity for teaching these things to people new to glow or experienced for that matter. My videos are simply for entertainment purposes only.
@@dmrcflyr2 My mistake .
Sorry about the nicked prop. That sucks!!!
I went too lean once.
Only once. I learned.
I mentioned in a previous video that I had heard that these FA-150 have higher comp ratio than the FA-180 and Dave rightly shut me down for not having a source for the info (other than hearsay...). Dave, do you have a way to measure compression ratio? Would be interesting to finally know once and for all.
I don’t measure compression ratio but there is a way to do it. I read the reviews on the engines to get my information
You weren't wrong. This engine has a very high compression ratio. You can feel it and you can see the empirical evidence of it throwing a prop. It's not hard to measure; you just have to fill the combustion chamber with water through the glow plug hole. Filling it with a burette makes it easy. The valves have to be closed and the engine should be tilted so no air is retained in the combustion chamber. Measure the volume at BDC and TDC. The difference is used to calculate the compression ratio.
To get all the potential power out of an engine, sometimes it becomes less user friendly.
i have two nuts on my prop and never has done this ....i really overtighten and now use nylon props due to not trusting wood....i should do but dont.
if you dont find the front drive washer,let me know. i may have an extra one
Hey David, is that an issue with any 4 stroke?
I believe I mentioned that in the conclusion.
If you replace the wood propeller with a heavy propeller, it works better.
Worst thing you can do to any 2 stroke is run it lean.
I believe that applies to any internal combustion engine sir. Not just 2 strokes....
@@dmrcflyr2 Otto cycle engines yes,diesel always run lean whether 2 or 4 stroke.
very weak audio
Try turning your speakers up. It is the same audio level as all other videos.
@@dmrcflyr2 the engine sounded fine, we can barely hear you speak