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That would be the easy way, but I think the lateral balance would be way off and require adding weight to correct. The manual says the problem doesn't occur when mounted upright, but the plane I was going to use this engine in a plane that now has a DLE 30,. Plane is designed with cooling for an inverted engine. I may end up putting in a new plane instead. Regards
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A while ago I power-dived a model nose-first into the ground with an FA-82B in it. At least it came down in sand, and not too hard packed. I wanted to check the crank wasn't bent and there was a lot of sand around and inside the throttle body, so I had to be sure none got into the head or cylinder. It would have if I'd tried to run it again without a thorough clean-out. So with my dad's help (he's a retired mechanical engineer) I partly dismantled it, cleaned it and checked for damage. As I'd heard people say, this engine has survived the crash just fine. I was very careful about cleaning the sand out from everywhere. I didn't want to fully dismantle it but at my dad's prompting I removed the cylinder, washed it out with petrol and checked it over.
That's the first time I've gone any further than removing a carby or rocker covers. The crank's fine, after clean-up and reassembly it turns freely without any sign of trouble from the crank or bearings. I didn't dismantle any of the valve train, and there was no need to mess with the bottom end. (If you do try this, make sure you don't get any dirt in there yourself while it's opened up). I'm more impressed than ever with my 2 Saito engines (also got an FA-56 that suffered a lesser crash but still had the sand issue so we checked them both). They're full of great little precision parts and design features. Easy to work on. Best of all, it's gone nose-first on power vertically into the ground, punching the engine and firewall several inches straight back into the cabin, yet the engine's fine with a clean up and check. That's a good engine in anyone's book, on top of ease of use and great performance. Just had to share that. |
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Latest blog entry: YS 1.60 Zero Nitromethane
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It's definitely to their credit, these are nice machines. My dad knows a thing or two about engines and machines and was impressed, and thoroughly enjoyed getting amongst the nifty little parts. He'd downloaded the manual and by the time I got there he was all "wow look at that nice assembly" and so on. When he found out the cam gear/lobes component was sintered that sealed it, he's impressed (can't wait to show him the YS 91AC then...) And a good thing to do with my dad for a few hours.
I don't know about in the USA but here in Australia Saito actually has a strong price advantage over OS 4-strokes... I think it's not so much that Saito is cheaper than OS is expensive, but the Saitos are a great buy. Years ago you could get ASP and Magnum 4-strokes cheap, but they've come up a lot and closed much of the gap, so to my mind I'd rather save up and buy the better engine. I've really noticed those cheapest engines are more prone to breaking down. $4 servos, well you can throw them away when they fail, but they do fail more often, and out of every 10 you might get 1 or 2 that from new just aren't right. To me, it's not always best to simply get the cheapest, but I realise that stuff is very helpful to people who couldn't access the hobby without it. So, for the price, I'm a Saito fan officially. After seeing what these two engines went through and the way they handled it, I'm convinced. I've always like these engines but that's the icing on the cake. Gary, thanks for that, looking forward to it. In the meantime i made a temporary hatch that clears the older-style muffler but it will be nice to use the new one and the proper hatch for this model. Much appreciated. |
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I got hooked on Saitos in 1991 or 92 when my daughter bought me the first Saito 1.50S sold. Even with 11.24 to 1 compression I liked it. A few months later I bought an older but new Saito .80 with 15.5 to 1 compression. I never lowered the compression, that just seems like, (going backwards), to me.
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I don't know if that's the usual compression ratio for 4-strokes this size but it would be pretty high for a car. Saito reminds me of those frightening Japanese racing motorbikes, high performance and nicely made. They're nice kit.
Thank you Gary Cee, I received the muffler and pipe today! Turns out it'd been waiting for me at the post office for almost 2 weeks and the card to notify me was buried under junk mail so I never saw it. Lucky I did because after today they would have returned it. It fits great and allows me to use the hatch I'd made for this trainer originally, so that's mighty helpful and I appreciate it. It's another excellent Saito thin-walled casting, they're good at it. Something confuses me though - why does the nipple on the muffler provide pressure to the fuel tank and not vacuum? I don't get why it's not a venturi. It obviously works, I just can't work out how. Is it because the gas flow is restricted at the exit, creating positive pressure inside the expansion chamber? That's all I can think of but I thought the idea was to design them so that back pressure was minimal, that's why the final outlet diameter's like the input dia. |
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The exhaust comes out in pulses or waves of pressure, there is high pressure in the cylinder and when the exhaust valve opens it bursts out, hence the bang. The pressure tap passes the average of the pulses on to the tank. If a check valve is used on the pressure tap the check valve captures the peaks of the pulses and the pressure can be pretty high. A regulator is then needed to control the fuel flow. That's the nutshell version.
PS, you check through these Saitos tested by Clarence Lee and Peter Chinn. You'll see compression ratios from 6.6 to 1 up to 15.5 to 1. The engine in the link is a .91s and is typical of today's. http://sceptreflight.net/Model%20Eng...%20FA-91S.html |
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Thanks for letting me know it got there OK. I was starting to get a bit concerned ! Glad to help. BTW , I did run my HC Saito 80 on both high and low compression and much preferred the overall running character that was provided by the lower compression . One of my flying buddies liked the change in mine so well that when he rebuilt his HC 80 we made the CR change on his too. That one is still in use almost 20 years later. Glad that I took the time to make the change. I would do it again in a minute. ![]() |
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Latest blog entry: YS 1.60 Zero Nitromethane
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Gary, did he lower it by using a flat topped piston in place of the piston with the hump? Thanks, Dave
I tamed mine this way, although it was never a problem, I run 10% fuel exclusively. Full synthetic too, Shhhh, don't spread that around, OK. |
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We both used a simple brass shim. Very light in weight and simple. Being a glow engine, we left them that way. Fine running engines.
Yep, full synthetic I know. Been there, did that too. I like the present results much better. 14% nitro , 14% oil (2% of that oil being castor) No rust no noticeable valve train wear, no varnish, no reason to go back. |
Latest blog entry: YS 1.60 Zero Nitromethane
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