Saito FG-20 or 21
#1777
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I just picked up a cub recently with the Saito FG-20. I seem to have a similar problem on my engine. The engine will idle fine and run fine a above 7000, but nothing in between. I tried the base setting on low speed and the results are the same. Not sure how long the engine has been sitting. High speed on a 16 x 6 MS is 8500. Sound of the engine at idle and at high speed sounds smooth.
#1779
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This might sound silly, try running 4 stroke glow fuel thru it with the ignition. Before I sold mine, that was the only way I could run it. The problem with that Saito motor is it's a glow needle valve trying to run gas, doesn't work. Works fine with glow fuel and you never have a dead stick. Problem is you are still using expensive glow fuel so no savings....
#1782
Mustangherb; I have been running my FG20 in my TF Spitfire since 2010 and it runs very well and sounds awesome. I love my Saito's, FG20, FG36, FG60R3 and my FA100. I have never had a problem with the FG20 since HH sent me a replacement carburetor in 2010. Your FG20 may have the old carburetor, the one that was a problem until they replaced it free of charge to customers back then. Check the part number on the carburetor, if it's not part number SAIG20821A than it's the problem carburetor you have on your FG20. Just for your info, HH has carburetor SAIG20821A in stock.
Roger
Roger
#1784
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Mustabgherb,
Ditto on what ForcesR said - make sure you have the new carb with the pin hole
Also get a CH Ignition kit for the FG-20, that did it for me - like a different engine!
Pic of the carb pin hole:
Ditto on what ForcesR said - make sure you have the new carb with the pin hole
Also get a CH Ignition kit for the FG-20, that did it for me - like a different engine!
Pic of the carb pin hole:
#1788
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My experience so far with a plane I picked up recently that had a extreme low time Saito FG-20 was right inline with most of the problems talked about on the forums. My engine even still has the original carb. Call me stubborn, but I went to work to see if I could get the engine to run correctly. I pulled the engine from the plane to install it on the stand and the first thing that I discovered on the very first run on the stand was studder in the engine if I moved the ignition module. After some investigation I discovered an error from the factory in the crimping of the wires onto the pins in the plug of the pickup. After correcting that problem the engine studder cleared up, but the midrange still needed work. It took me two things to fix this problem. One I installed fuel barbs & zip ties on all the tank lines inside and out. Secondly I played a round with the tank placement and now the engine is running great in all the flight conditions in the plane. I must admit that I was worried after reading some of the horror stories, but you just have to ensure that the fuel system is tight(I installed fuel barbs), the module plugs are crimped correctly and that you get the fuel tank placement right. I must admit that after reading through this threads that I seriously had my doubts about the engine, but I flew the plane several times today and the engine is running fantastic.
#1789
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Join Date: Jul 2011
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So I picked up a low time FG20 and after reading this, I guess I know why it hasn't been running a lot...
Anyways - it had been crashed and needs a few parts. Besides push rods and sleeves and a broken needle valve I'll need a muffler and fitting - would an ASP part fit here?
The carb seems to be the old version, so I need to decide if I get just the broken parts or an upgraded carb.
What's a good source for spare parts?
thanks
Anyways - it had been crashed and needs a few parts. Besides push rods and sleeves and a broken needle valve I'll need a muffler and fitting - would an ASP part fit here?
The carb seems to be the old version, so I need to decide if I get just the broken parts or an upgraded carb.
What's a good source for spare parts?
thanks
#1790
Hmm, I seem to recall someone selling that engine on FB. Didn't realize the exhaust was mucked up too. You can get parts from Horizon. Look into maybe a turbo header instead of stock muffler, gives it more power.
#1792
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Thanks, I just put on an order with Horizon, except the muffler.
I may have one laying around here, i just want to make sure I get this engine to run before buying more parts.
Not such a great deal after all, but there is no turning back, I'll get it going sooner or later
I may have one laying around here, i just want to make sure I get this engine to run before buying more parts.
Not such a great deal after all, but there is no turning back, I'll get it going sooner or later
#1795
The difficulties with the FG-20 narrated here caught my interest as I've recently converted a 1.25A to gas with minimal problems using the stock carb. Muffler pressure is used and tuning is tight but not much more so than my Evolution gas engines.
Idle was a bit of a problem but was solved by using a throttle servo speed delay of one second. The delay allowed leaning the idle up enough to get the carb barrel closed to a more normal idle position. Without the delay, idle had to be fat with a somewhat open barrel and of course that restricted it to a fast idle.
Leaning the idle to obtain a smoother and lower idle introduced a spool up stumble that would kill the engine but that was overcome with servo speed slow down. The slow down really doesn't effect flight as spool up happens in about the same time frame, it just prevents a drastic upset of the fuel/air/rpm ratio by opening the barrel and drawing out the metering needle at a speed that gives the rpms enough time to keep up to the changes.
If stumbling is a problem with the FG-20, try a servo speed slowdown.
Idle was a bit of a problem but was solved by using a throttle servo speed delay of one second. The delay allowed leaning the idle up enough to get the carb barrel closed to a more normal idle position. Without the delay, idle had to be fat with a somewhat open barrel and of course that restricted it to a fast idle.
Leaning the idle to obtain a smoother and lower idle introduced a spool up stumble that would kill the engine but that was overcome with servo speed slow down. The slow down really doesn't effect flight as spool up happens in about the same time frame, it just prevents a drastic upset of the fuel/air/rpm ratio by opening the barrel and drawing out the metering needle at a speed that gives the rpms enough time to keep up to the changes.
If stumbling is a problem with the FG-20, try a servo speed slowdown.
#1796
That is actually a pretty good idea. I'll have to remember that trick. It should also work on glow engines. I have an OS that is finicky at times. I think I may need to replace the o rings on the LSN on that one as the low end keeps changing.
#1799
My Feedback: (3)
No
Wow they both cracked? Can you post a pic that shows how they were mounted? If they are in a cowl and don’t have heavy airflow thats aimed directly over the head with some custom made baffling then they will get screamin hot. I’m guessing the aluminum softened up and cracked due to excessive heat.