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Old Aug 07, 2012, 04:40 AM
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Question
Saito FG-20 vs FG-21

Some time ago, Saito produced the FG-20. It seems Saito have replaced this with the FG-21?

Anyone know why?
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Old Aug 07, 2012, 06:23 AM
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An improved carb, a slightly larger bore for a very slight increase in displacement, and a better exhaust valve seat is what Saito said they did.
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Old Aug 07, 2012, 07:08 AM
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Thanks earlwb.

So was the carb improvement only required for the FG-21 (nee FG-20) model? Did it get adopted in the 14B and 17 variants?

I love my FG-14B by the way. It's like jewelery.
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Old Aug 07, 2012, 10:14 PM
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Plus an Excel ignition.

The FG20cc had a bad rep in some quarters. In my view, Saito probably bored it out to 21cc for marketing purposes (eg so it can be kept/marketed separate from the earlier FG20).
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Old Sep 03, 2012, 02:32 PM
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Saito FG21

I would like to add my experience, because I have had both engines. The FG20 was wholly unreilable. MacGregor here in the UK replaced the ignition unit twice and the carb 3 times. It was so diificult to tune and from one day to the next the needle settings would vary a lot. I had loads of dead sticks and ruined two aircraft because of it. I eventually destroyed it with a headlong dive into tarmac when the elevators detached themselves - I was not at all sorry to see it go...

When the FG 21 came out I was full of optimism - the RCEXEL ignition unit was clearly much better - BUT the carb is still crap in my opinion. As before it will not hold a setting between one session and the next. I tune it on the ground - have it running on idle for 5 minutes - wack open the throttle and get 8500 revs tuned back from 9200. Yet in the air it will cut out without warning. Some might say it is over heating - but this is flying without a cowl. In the cowl it overheats all the time. I have built in cooling tubing to direct air directly over the engine and generous air extract - but still it over heated.

So I fly it with no cowl - but it still makes no difference. What I have also noticed is that when I lean the engine to find peak revs I can then make the mix richer but even half a turn or more of the needle valve and it is still running at its peak! I have to close and open the throttle to get the carb to take the new setting. Quite stupid. This is a relatively new engine, and I have filters in the tank and the fuel line and I filter the fuel in my dispenser.

Today I had yet another dead stick and ripped the undercarriage out. So that it is it - I have wasted so much time on it - it will now sit on shelf to remind me never to buy one of these little engines again. This is such a pity because the four stroke sound is so sweet. I have two FG30's and an FG57 and I have never had any grief from them. So my advice is to stay well clear of the FG20 and FG21.
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Old Sep 04, 2012, 10:25 PM
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I've been flying the FG 20 now for about 6 months with about 30 hours on the engine. I initially had problems getting the fueling right and then had problems with overheating due to using a larger prop than recommended. I must say it took me a good while to get it running correctly. However, for me, it was worth it. I've had over 20 hours now of flawless running.

The economy is outstanding. I'm using it on a 17lb VQ Pilatus Porter and a 500ml tank lasts for over an hour flying time and associated take off and landings. I sometimes run it continuously for over an hour, with four or five take-off/landings, and it never misses a beat whether at idle or flat out.

Having said this, I would go with the FG 21 if you are still thinking of getting this engine because it is a newer model.
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Old Nov 07, 2012, 09:50 AM
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Saito fg20cc

I have a brand new in box SAITO FG20cc NO fuel went through it. As i can understand from one of the above comments that the new FG21CC has a new improved carb. Is it possible to replace the FG20CC carb with the new version FG21CC carb. ?
Having read so many negative comments about this engine i might be inclined to sell this little jewel. I bought this engine at the 2011 Toledo show.

To the aussies, good day mates !

Charles.
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Old Nov 08, 2012, 12:18 AM
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Quote:
Originally Posted by Garthwood View Post
I have a brand new in box SAITO FG20cc NO fuel went through it. As i can understand from one of the above comments that the new FG21CC has a new improved carb. Is it possible to replace the FG20CC carb with the new version FG21CC carb. ?
Having read so many negative comments about this engine i might be inclined to sell this little jewel. I bought this engine at the 2011 Toledo show.

To the aussies, good day mates !

Charles.
G'day Charles,
If you contact Horizon Hobbies, with proof of purchase for your FG20, they will supply a FG21 carby, & you will be on your way.
I have a FG21, have been running it on the test bench, runs like a swiss watch.
Sweet running engine, love it, I will install it on a Spacewalker, soon.
Cheers
Allan
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Old Jan 11, 2013, 02:20 PM
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Quote:
Originally Posted by profmb View Post
I would like to add my experience, because I have had both engines. The FG20 was wholly unreilable. MacGregor here in the UK replaced the ignition unit twice and the carb 3 times. It was so diificult to tune and from one day to the next the needle settings would vary a lot. I had loads of dead sticks and ruined two aircraft because of it. I eventually destroyed it with a headlong dive into tarmac when the elevators detached themselves - I was not at all sorry to see it go...

When the FG 21 came out I was full of optimism - the RCEXEL ignition unit was clearly much better - BUT the carb is still crap in my opinion. As before it will not hold a setting between one session and the next. I tune it on the ground - have it running on idle for 5 minutes - wack open the throttle and get 8500 revs tuned back from 9200. Yet in the air it will cut out without warning. Some might say it is over heating - but this is flying without a cowl. In the cowl it overheats all the time. I have built in cooling tubing to direct air directly over the engine and generous air extract - but still it over heated.

So I fly it with no cowl - but it still makes no difference. What I have also noticed is that when I lean the engine to find peak revs I can then make the mix richer but even half a turn or more of the needle valve and it is still running at its peak! I have to close and open the throttle to get the carb to take the new setting. Quite stupid. This is a relatively new engine, and I have filters in the tank and the fuel line and I filter the fuel in my dispenser.

Today I had yet another dead stick and ripped the undercarriage out. So that it is it - I have wasted so much time on it - it will now sit on shelf to remind me never to buy one of these little engines again. This is such a pity because the four stroke sound is so sweet. I have two FG30's and an FG57 and I have never had any grief from them. So my advice is to stay well clear of the FG20 and FG21.

Any update on how things are going on now with your FG-21?
It's quite confusing to notice you have had such a bad luck with the FG-21 while some others have found the engine to be reliable. Are you sure you haven't overpropped it?

CH Ignition has experimented the Zama carb in conjunction with the FG-21 with good luck. Just for your consideration.

Btw. why do you think you are luckier with the FG-30?
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Old Jan 11, 2013, 02:41 PM
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The FG21 is $505.

W/the C&H conversion you can convert the FA125 to gas for just a little more than that & have a better ignition system & more reliable carburetor to boot. The system for applying the trigger magnet & hall sensor is much better on the C&H system too. It is much easier to set up & make adjustments than the Saito/RCEXEL system.

C&H originated the synchrospark CDI systems back in 1997. I have 3 of those systems & they still work flawlessly. RCEXEL copied the module (but not the trigger magnet/sensor mounts) to make cheap Chinese knock offs.

FA125 ..........................................$375
CH complete gas conversion kit..$150
Total............................................. .$525

Many end up replacing the module & carb on the Saito FG engine W/the C&H parts to get reliable operation. Why not just go the C&H route W/the FA125 in the 1st place & avoid the added expense/headaches?
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Old Jan 12, 2013, 05:44 AM
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Originally Posted by SrTelemaster View Post
The FG21 is $505.

W/the C&H conversion you can convert the FA125 to gas for just a little more than that & have a better ignition system & more reliable carburetor to boot. The system for applying the trigger magnet & hall sensor is much better on the C&H system too. It is much easier to set up & make adjustments than the Saito/RCEXEL system.

C&H originated the synchrospark CDI systems back in 1997. I have 3 of those systems & they still work flawlessly. RCEXEL copied the module (but not the trigger magnet/sensor mounts) to make cheap Chinese knock offs.

FA125 ..........................................$375
CH complete gas conversion kit..$150
Total............................................. .$525

Many end up replacing the module & carb on the Saito FG engine W/the C&H parts to get reliable operation. Why not just go the C&H route W/the FA125 in the 1st place & avoid the added expense/headaches?
I'v been thinking about this route, too.

However, one thing that is confusing is the Zama in conjunction with the FG 20 seems to give about 8100-8300rpm with 16X6 evolution prop as peak according to Adrian's experiments . The original Saito carb seems to perform better what comes to max power output: about 8500-8800rpm with 16x6 apc or equivalent prop according to various tach readings reported?

Why?
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Old Jan 12, 2013, 07:02 AM
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I would bet that the difference is because one carb has a slightly larger venturi bore to it.
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Old Jan 12, 2013, 08:10 AM
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Quote:
Originally Posted by AeroFinn View Post
I'v been thinking about this route, too.

However, one thing that is confusing is the Zama in conjunction with the FG 20 seems to give about 8100-8300rpm with 16X6 evolution prop as peak according to Adrian's experiments . The original Saito carb seems to perform better what comes to max power output: about 8500-8800rpm with 16x6 apc or equivalent prop according to various tach readings reported?

Why?
Only when tach readings are done back to back W/the same prop on the same day at the same location, can #s be used as a comparison. When making difinitive power gain tests I always do that. I have seen 200 RPM varaince W/my FA300TTDP CDI when I broke the original 22X8 Zinger & replaced it W/anoter 22X8 Zinger.

Adrian seldom experiments W/ignition timing beyond the 28* initial setting. A bit more advance might also boost power output. It certainly does when burning methanol W/CDI.

Adrian's tests could have been done on a day W/high humidity or windy conditions.

I also suspect that some manifold work to blend the bore of the ZAMA carb to the manifold diameter would help.

On my FA180HC CDI engine I gained .45HP when I modified an FA150 intake manifold to the ID of the FA220 Big Bore carb on the updraft portion & opened up the horizontal portion that joins the head to the size of the 180 intake port. I doubt that I would have seen that much gain from just bolting the big 12mm 220 Big Bore catb onto the standard 11mm bore FA180 intake manifold.

Once CDI is introduced into the equasion, there is lots of room for various tweeks to maximize power output. That's why I convert all of my Saitos to CDI even though I still burn methanol feul. The ignition timing can be adjusted to take advantage of the various tuning needs that arrise.

Besides, which is better, an engine that makes 8300 RPM of dependable power, or an engine that might make 300 RPM more that is unreliable?
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Old Jan 12, 2013, 08:22 AM
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Originally Posted by earlwb View Post
I would bet that the difference is because one carb has a slightly larger venturi bore to it.
So you bet the Saito carb has a larger venturi bore? If this is the case I wonder if the venture bore of the Zama carb could be enlarged to match with that of the Saito carb..?
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Old Jan 12, 2013, 10:33 AM
I HATE GLOW PLUGS!
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Quote:
Originally Posted by AeroFinn View Post
So you bet the Saito carb has a larger venturi bore? If this is the case I wonder if the venture bore of the Zama carb could be enlarged to match with that of the Saito carb..?
I think the ZAMA has a larger bore than the Saito since it is the same carb used for the 120/150/180 conversions. A carb W/an abrupt step down to a smaller I D manifold can cause issues.

Quote:
Originally Posted by SrTelemaster View Post
On my FA180HC CDI engine I gained .45HP when I modified an FA150 intake manifold to the ID of the FA220 Big Bore carb on the updraft portion & opened up the horizontal portion that joins the head to the size of the 180 intake port. I doubt that I would have seen that much gain from just bolting the big 12mm 220 Big Bore catb onto the standard 11mm bore FA180 intake manifold.

Once CDI is introduced into the equasion, there is lots of room for various tweeks to maximize power output. That's why I convert all of my Saitos to CDI even though I still burn methanol feul. The ignition timing can be adjusted to take advantage of the various tuning needs that arrise.
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