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Old Jan 13, 2013, 03:45 PM
I HATE GLOW PLUGS!
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United States, NY, St Lawrence
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Originally Posted by AeroFinn View Post
SrTele,

-> I guess I have to have a closer look to the carb design to see if some machine work might do the trick and help install a carb barrel spring of some kind.

I think your remark of checking the throttle linkage is another thing I have to do as I do not have ball link on the throttle arm so this may worsen the phenomenon in question.
Removing some material from the spring end of the barrell might do the trick.

I hobbled up stairs to my hanger room & yews, the 1 carburetor I checked on my FA150 did exibit slight endplay.

Under vibration, I wonder how much the barrel spring will prevent the barrel from oscillating.
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Old Jan 13, 2013, 10:52 PM
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Originally Posted by SrTelemaster View Post
Removing some material from the spring end of the barrell might do the trick.

I hobbled up stairs to my hanger room & yews, the 1 carburetor I checked on my FA150 did exibit slight endplay.

Under vibration, I wonder how much the barrel spring will prevent the barrel from oscillating.
Did that carb have a spring to push the barrel toward the lever end?
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Old Jan 14, 2013, 08:29 AM
I HATE GLOW PLUGS!
SrTelemaster's Avatar
United States, NY, St Lawrence
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Originally Posted by AeroFinn View Post
Did that carb have a spring to push the barrel toward the lever end?
Yes tthe 120/150/180/220 carbs all have the spring.
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Old Jan 14, 2013, 04:11 PM
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Originally Posted by SrTelemaster View Post
Yes tthe 120/150/180/220 carbs all have the spring.
Ok! Then there must be a reason for the spring! I guess..

I re-checked the FA-125a carb and the enplay is somewhat 0,5-1mm so definitely great likelihood to cause the idle hunt at certain rpm range . And it seems there is not much space between the barrel and the carb body to installa a spring. I guess the only possibility might be to remove some material from the spring end of the barrel (as you suggested). Will have to look at this closer..

EDIT: ok it doesn't seem to be an easy job to remove material from the spring end of the barrel which seems to made of a thin material at the end. I guess I need to find a spring of the right size and hope for the best. Or find another suitable glow fuel carb. Then I might be able to create a throttle linkage that prevents the end play of the carb barrel, too. (This latter alternative might be actually the most feasible solution with glow fuel route as no fuss with testing different carbs.)

(Or the go the gas route with Adrian/Zama carb.)
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Old Jan 14, 2013, 04:16 PM
I HATE GLOW PLUGS!
SrTelemaster's Avatar
United States, NY, St Lawrence
Joined Feb 2012
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Originally Posted by AeroFinn View Post
Ok! Then there must be a reason for the spring! I guess..

I re-checked the FA-125a carb and the enplay is somewhat 0,5-1mm so definitely great likelihood to cause the idle hunt at certain rpm range . And it seems there is not much space between the barrel and the carb body to installa a spring. I guess the only possibility might be to remove some material from the spring end of the barrel (as you suggested). Will have to look at this closer..
I would estimate the end play on the FA150 carb barrel to be less than .025mm.
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Old Jan 16, 2013, 04:47 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?
SrTele

There are lot of us who have a FA-125a already that may need service in anyways (as an example mine needs a new cylinder & piston anyways) so the gas conversion could possibly be done by converting the FA-125a to hybrid of FG-21 / FA-125a:

FG-21 cylinder (to have the latest valve design cylinder and thus a more heat tolerant engine).................$134
FG-21 piston............................................ ............................................$34,19
FG-21 piston ring.............................................. ...................................$23,3
FG-21 connecting rod (more tolerant to lower oil content)...................$24,85
CH complete gas conversion kit............................................... ............$150
Total............................................. .................................................. .......$366,34

all other parts from the FA-125a (with assumption the needed FA-125 parts, such as valves, crankshaft etc. fit in conjunction with the associated FG-21 parts) I'm not sure..I would like to know what is the case in real!

The benefit of this hassle: get more reliable ignition & carb than the stock ones + the latest gas engine valve and connecting rod design at reasonable price (provided with a FA-125a engine sits unused at the work shop..)
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Old Jan 16, 2013, 08:42 AM
I HATE GLOW PLUGS!
SrTelemaster's Avatar
United States, NY, St Lawrence
Joined Feb 2012
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Originally Posted by AeroFinn View Post
SrTele

There are lot of us who have a FA-125a already that may need service in anyways (as an example mine needs a new cylinder & piston anyways) so the gas conversion could possibly be done by converting the FA-125a to hybrid of FG-21 / FA-125a:

FG-21 cylinder (to have the latest valve design cylinder and thus a more heat tolerant engine).................$134
FG-21 piston............................................ ............................................$34,19
FG-21 piston ring.............................................. ...................................$23,3
FG-21 connecting rod (more tolerant to lower oil content)...................$24,85
CH complete gas conversion kit............................................... ............$150
Total............................................. .................................................. .......$366,34

all other parts from the FA-125a (with assumption the needed FA-125 parts, such as valves, crankshaft etc. fit in conjunction with the associated FG-21 parts) I'm not sure..I would like to know what is the case in real!

The benefit of this hassle: get more reliable ignition & carb than the stock ones + the latest gas engine valve and connecting rod design at reasonable price (provided with a FA-125a engine sits unused at the work shop..)
I think you will also need the FG-21 intake manifold as the FG-2 is different.

I was contemplating buying a used FG-21 from a disgruntalled owner to convert to glow fuel/CDI, but the manifold/cylinder head interface is entirely different than the FA125/FG-20.

The price the guy wanted made the conversion not cost effective.
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Old Jan 16, 2013, 09:44 AM
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I think you will also need the FG-21 intake manifold as the FG-2 is different.

I was contemplating buying a used FG-21 from a disgruntalled owner to convert to glow fuel/CDI, but the manifold/cylinder head interface is entirely different than the FA125/FG-20.

The price the guy wanted made the conversion not cost effective.

Ok thanks so this will add up the total costs to: $366,34+$25.19=$391,53

wether this makes sense, up to each and everyone..But compared to new FG-21 + CH complete gas conversion kit =$504,99+$150=$654,99 there is still a difference of more than $250
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Old Jan 16, 2013, 01:28 PM
I HATE GLOW PLUGS!
SrTelemaster's Avatar
United States, NY, St Lawrence
Joined Feb 2012
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Originally Posted by AeroFinn View Post
Ok thanks so this will add up the total costs to: $366,34+$25.19=$391,53

wether this makes sense, up to each and everyone..But compared to new FG-21 + CH complete gas conversion kit =$504,99+$150=$654,99 there is still a difference of more than $250
Why don't yuou convert your FA125 ($115) to CDI & run the engine for a while on methanol?

You'll get about 20% more power on CDI/methanol than you will on gas. (5-6% more than glow ignition W/similar fuel)

You can run 0% nitro & drop lube to the 8-10% range.

You might like it so much that you'll forget all about gasoline.

Of you live near a big citty, you can buy a 55 gallon drum of methanol for $100.
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Old Jan 16, 2013, 03:59 PM
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Originally Posted by SrTelemaster View Post
Why don't yuou convert your FA125 ($115) to CDI & run the engine for a while on methanol?

You'll get about 20% more power on CDI/methanol than you will on gas. (5-6% more than glow ignition W/similar fuel)

You can run 0% nitro & drop lube to the 8-10% range.

You might like it so much that you'll forget all about gasoline.

Of you live near a big citty, you can buy a 55 gallon drum of methanol for $100.
Yeah..This seems to be the best alternative even though it may be such that you can't really run the FA-125a on gas reliably in any longer term (even if you'd like to do so after a while) due to the connecting rod & valve seat design. And while the valve design issue might be overcome by paying special attention to the engine cooling arrangement the connecting rod design remains bad for the gas running purpose as you pointed out in one of your posts.

So it's like you have to decide which you want: If gas then it's the FG-21 block & connecting rod.

I was (for a little while) tempted by the FG21/FA-125 hybrid as I dismantled my FA-125a engine and I realized I'm probably in need of a new cylinder anyways. And the first impression was the prices for the FG-21 and FA-125 cylinders were practically same. However, when you add up all the needed parts to use the FG-21 cylinder it won't pay back the hassle. (Besides I found an un-used FA-125a piston & ring in my workshop..)

What you say about oil content is definitely alluring.. less mess to wipe off at the end of the day!

I will be using Aerosave or Aerosynth3 oils which are both of very high quality oils (superior to Klotz I believe, hopefully I'm not opening any can of worms with this statement ) so I think I should have chances to go to the 8-10% range.

So I think it's about the time to send e-mail to Adrian. Is there now something I'd better let him know? I Do not understand how the ignition systems works at all on top of it gives spark to the spark plug..for instance, all these things such as automatic advance curves etc. is chinese to me..

P.S. I did some googleing on how to carry out the FA-125a carb modification but I could not find any hints. I guess if the spring won't fit inside then the only feasible option is to try to create a throttle linkage that "pulls" the barrel to the lever end
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Old Jan 16, 2013, 07:12 PM
I HATE GLOW PLUGS!
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United States, NY, St Lawrence
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Originally Posted by AeroFinn View Post
So I think it's about the time to send e-mail to Adrian. Is there now something I'd better let him know? I Do not understand how the ignition systems works at all on top of it gives spark to the spark plug..for instance, all these things such as automatic advance curves etc. is chinese to me..
The spark curve is more of a retard than advance. When you set the system up you are setting the initial spark @ full advance. With methanol, that's going to be about 34-36* BTDC (you will make small adjustemnts after starting to find the minimum advance that gives maximum RPM)

I read how some are trying to static time by the magnet/hall sensor position relationship. That seems like a haphazard way. By removing the plug from the cylinder & installing it in the McDaniels plug socket, you can see/hear the spark event. No need to ground the plug as the socket/lead are grounded to the module via the braided SS shiled on the lead. I use the spark plug W/a degree wheel & slowly turn the engine through the spark event, carefully noting the reading on the degree wheel as I see/ear the spark.

Back to the timing curve. W/the spark set @ the full advance setting, the module will retard the spark 24* @ low RPM settings. (about 400 RPM & slightly above) This allows starting W/O kickback & good idle. As the RPM increase, the module backs off the retard until it reaches the initial setting @ 4000+ RPM.

If you haven't seen my thread about setting up C&H CDI here is the link.

http://www.rcgroups.com/forums/showthread.php?t=1774802
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Old Jan 18, 2013, 04:51 AM
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Originally Posted by SrTelemaster View Post
The spark curve is more of a retard than advance. When you set the system up you are setting the initial spark @ full advance. With methanol, that's going to be about 34-36* BTDC (you will make small adjustemnts after starting to find the minimum advance that gives maximum RPM)

I read how some are trying to static time by the magnet/hall sensor position relationship. That seems like a haphazard way. By removing the plug from the cylinder & installing it in the McDaniels plug socket, you can see/hear the spark event. No need to ground the plug as the socket/lead are grounded to the module via the braided SS shiled on the lead. I use the spark plug W/a degree wheel & slowly turn the engine through the spark event, carefully noting the reading on the degree wheel as I see/ear the spark.

Back to the timing curve. W/the spark set @ the full advance setting, the module will retard the spark 24* @ low RPM settings. (about 400 RPM & slightly above) This allows starting W/O kickback & good idle. As the RPM increase, the module backs off the retard until it reaches the initial setting @ 4000+ RPM.

If you haven't seen my thread about setting up C&H CDI here is the link.

http://www.rcgroups.com/forums/showthread.php?t=1774802
Great thread! I'v read it through a couple of times now
And this timing curve idea came clear, too.
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Old Jan 18, 2013, 06:51 AM
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Originally Posted by SrTelemaster View Post

The spark curve is more of a retard than advance.
I don't agree, Sr..

Although the ignition system does initiate the spark by delaying the signal timing, the spark is always advanced in relation to the piston at TDC.

I understand the magnet interacts with the Hall sensor at a crankshaft angle of about 40; and from there it is is delayed for very low RPM, until the crankshaft is 6-10 BTDC.

At starting it us even less advanced, so more delay is set in.
I heard of 0, until the system determines the engine is already running

If the spark would fire @ 40 BTDC when the prop is being flipped to start, even the lowest flame propagation speed, would bring on maximum cylinder pressure when you're at 35 BTDC; and you'll be feeling some major kick-back.

The spark never occurs ATDC, so it is never retarded; just less advanced.
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Old Jan 18, 2013, 10:04 AM
I HATE GLOW PLUGS!
SrTelemaster's Avatar
United States, NY, St Lawrence
Joined Feb 2012
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Originally Posted by DarZeelon View Post
I don't agree, Sr..

Although the ignition system does initiate the spark by delaying the signal timing, the spark is always advanced in relation to the piston at TDC.

I understand the magnet interacts with the Hall sensor at a crankshaft angle of about 40; and from there it is is delayed for very low RPM, until the crankshaft is 6-10 BTDC.

At starting it us even less advanced, so more delay is set in.
I heard of 0, until the system determines the engine is already running

If the spark would fire @ 40 BTDC when the prop is being flipped to start, even the lowest flame propagation speed, would bring on maximum cylinder pressure when you're at 35 BTDC; and you'll be feeling some major kick-back.

The spark never occurs ATDC, so it is never retarded; just less advanced.
The action that occurs is that the ignition timing is retarded (verb) from the initial setting. I think everyone reading my post might have made that connection.

I'm curious as to where do you get 40* BTDC? I can't imagine any production gasoline engine having an actual spark occurance @ 40* BTDC.

I think these 40* references are from the atempts to static time W/the appearance of the magnet/hall effect sensor. I doubt that a timing light would show 40* BTDC. About 36* BTDC is the most that will be tolerated W/O detonation on gasoline & only then @ higher RPM. Alcohol fuels would probably tolerate a bit more.

By checking W/a degree wheel observing the actual spark after tuning by incremental advance setting, I have found that W/methanol, around 34-35* BTDC yield the maximum RPM under load. More timing advance does not increase RPM & could lead to detonation. On a Saito FG series engine that has not had the CR reduced, as I would bet they are doing on the latest designs, anything beyond 28* BTDC would likely promote detonation.

As far as the reason I use CDI W/methanol?

My FA180HC CDI BBC engine can produce 3.45 HP on 15% nitro, 3.94 HP on 30%. In my other post I compared that powerr output to the FG36 @ 3 HP.

To be fair, it should be compared to the similar displacement/weight FG30. Saito has (wisely IMO) declined to publish HP output for the FG30. Using the usual 15% HP reduction that occurs in other Saito gas version engines compared to similar displacement GI versions, the likely power output of the FG30 would be about 2.4 P (2.8 x .85 = 2.38)

Compare 3.5Hp to 2.4 & the 15% nitro fueled FA180HC CDI BBC makes 46% more power Than the FG30.

The 30% fueled version makes a whopping 67% more power. Both of those scenerios will likely outlast the gas burning FG30 by a significant factor.

For me, the added power & probably increased engine life is worth the extra cost of methanol fuel, not to mention avoiding the smell of gasoline in my vehicle.

If you want to burn gasoline in a 4-stroke, (for me, a 2-stroke is not even in the realm of consideration) do it in one of these.

Cessna Bird Dog L-19 RC Roto 70 V2 boxer (3 min 12 sec)


Use an engine that was designed from the get-go for gasoline, not a converted non-roller bearing crank throw glow engine.
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Old Jan 18, 2013, 11:37 AM
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Originally Posted by SrTelemaster View Post
The action that occurs is that the ignition timing is retarded (verb) from the initial setting. I think everyone reading my post might have made that connection.

I'm curious as to where do you get 40* BTDC? I can't imagine any production gasoline engine having an actual spark occurance @ 40* BTDC.

I think these 40* references are from the atempts to static time W/the appearance of the magnet/hall effect sensor. I doubt that a timing light would show 40* BTDC. About 36* BTDC is the most that will be tolerated W/O detonation on gasoline & only then @ higher RPM. Alcohol fuels would probably tolerate a bit more.

By checking W/a degree wheel observing the actual spark after tuning by incremental advance setting, I have found that W/methanol, around 34-35* BTDC yield the maximum RPM under load. More timing advance does not increase RPM & could lead to detonation. On a Saito FG series engine that has not had the CR reduced, as I would bet they are doing on the latest designs, anything beyond 28* BTDC would likely promote detonation.

As far as the reason I use CDI W/methanol?

My FA180HC CDI BBC engine can produce 3.45 HP on 15% nitro, 3.94 HP on 30%. In my other post I compared that powerr output to the FG36 @ 3 HP.

To be fair, it should be compared to the similar displacement/weight FG30. Saito has (wisely IMO) declined to publish HP output for the FG30. Using the usual 15% HP reduction that occurs in other Saito gas version engines compared to similar displacement GI versions, the likely power output of the FG30 would be about 2.4 P (2.8 x .85 = 2.38)

Compare 3.5Hp to 2.4 & the 15% nitro fueled FA180HC CDI BBC makes 46% more power Than the FG30.

The 30% fueled version makes a whopping 67% more power. Both of those scenerios will likely outlast the gas burning FG30 by a significant factor.

For me, the added power & probably increased engine life is worth the extra cost of methanol fuel, not to mention avoiding the smell of gasoline in my vehicle.

If you want to burn gasoline in a 4-stroke, (for me, a 2-stroke is not even in the realm of consideration) do it in one of these.

http://www.youtube.com/watch?v=XMUZw19QJ7E

Use an engine that was designed from the get-go for gasoline, not a converted non-roller bearing crank throw glow engine.
My primary objectives to go for the CDI were to get:

l
  • ower reliable idle
  • less oil resid
ue to wipe off at the end of the flying day

I think there are many other modellers that share these objectives

I'm excited about the possibility run the engine on CDI/methanol with 8-10% oil in the fuel:

This reduces the oli residue considerably. And if excess power is not needed running on 0% nitro is possible with CDI which reduces the quantity of fuel burned by, say, 20%

less oil in fuel + less fuel burned = less oil residue to wipe off.

Cost concious modellers will see operation costs to drop by about 40-50% (especially in Europe where nitro is more expensive than in US) if they go from 15% nitro/ 15% oil fuel blend to 0% nitro/10% oil fuel blend

And I bet 0% nitro / 10% oil fuel blend gives more power than running on gas (this is, however, my assumption. I don't have any data to prove this)
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