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Old 07-31-2014, 04:24 PM
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Originally Posted by Hobbsy
AC, there is a connection there, many times the slowest idle and the best transition are not compatible, my choice is to go for the best transiton and live with a little higher idle speed. To me the instant response is preferable to the lowest idle.
That slow idles is when I hit the kill switch on the radio, I have the throttle servo closed as far as it will go and the engine just putts along until the glow plug finally cools down enough to quit. In the normal position I have the idle set just right.
Old 07-31-2014, 06:08 PM
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Sounds good then.
Old 08-01-2014, 01:13 AM
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Acdc the 90 twin has a nice vw kombi van broken exhaust header note have you heard one running ?

The comments on running in are good to read.Sometimes wonder if tuning skills are catching up with the fuel tank position in each different aeroplane,you can only compare different saito's by bench running them where the fuel tank is always in the same position.After running in 2 125's i don't like them.The 115 gave full performance within 2 hours,pulled like a train.It seems you have to mother the 125 initially they are so reluctant to perform.My 82's are flown most and after two or three months you don't touch the needles much.With the 182 twin when running it in i'd get huge rpm gains during the second and third tank runs without touching the needles,amazing and good fun to hear.
Old 08-01-2014, 02:09 AM
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Boy was that boring,can i add an i'm an idiot smile here,hope so
Old 08-01-2014, 02:38 AM
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Originally Posted by Old Fart
Acdc the 90 twin has a nice vw kombi van broken exhaust header note have you heard one running ?

The comments on running in are good to read.Sometimes wonder if tuning skills are catching up with the fuel tank position in each different aeroplane,you can only compare different saito's by bench running them where the fuel tank is always in the same position.After running in 2 125's i don't like them.The 115 gave full performance within 2 hours,pulled like a train.It seems you have to mother the 125 initially they are so reluctant to perform.My 82's are flown most and after two or three months you don't touch the needles much.With the 182 twin when running it in i'd get huge rpm gains during the second and third tank runs without touching the needles,amazing and good fun to hear.
I'm looking forward to having my Fa-125 to be completely run-in. I have no run about 2,5 gallons and still keeps changing characteristics. Maybe now during the last half a gallon I haven't touched the needles much. I'm still having the reliable idle at 2300+rpm. No way to try to go below that RELIABLY although the engine runs at 1900-2100rpm for a while.

I have succesfully modified the carb by installing a FA91 carb barrel spring (this requires a carefull grinding of excessive material in the carb body. Otherwise the spring won't fit in). This has helped a bit with the idle characteristics. Once my engine is run-in I will convert it to CH-Ignitions CDI (I already have the kit). I am pretty convinced that this will turn the engine to a very nice one as the CDI probably helps to reach a reliable idle at 1700-1900 rpm

Last edited by AeroFinn; 08-01-2014 at 02:40 AM.
Old 08-01-2014, 04:34 AM
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The carb spring is just a feel good thing and totally not needed. When carbs had an idle speed screw the springs helped because they were a sloppy fit in the groove.
Old 08-01-2014, 04:51 AM
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Originally Posted by Hobbsy
The carb spring is just a feel good thing and totally not needed. When carbs had an idle speed screw the springs helped because they were a sloppy fit in the groove.
Yep, no need for a throttle spring. I use the throttle trim to adjust idle & shut the engine down.

I also use it to reduce cylinder pressure so I can start large displacement engines (even my FA-300TTDP) W/a 90 sized electric starter. I only use the starter for he initial start if the day.

After the fuel system is primed & the engine warmed, I flip start.
Old 08-01-2014, 04:53 AM
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Originally Posted by Hobbsy
The carb spring is just a feel good thing and totally not needed. When carbs had an idle speed screw the springs helped because they were a sloppy fit in the groove.
Dave,

This is what I thought, too. However, just for comparison, the FA-115 which was released after the FA-125 has the carb spring. For obvious reason, I think. I can tell you, with all respect, that the 125 vibrates and the slack is considerable in the carb effecting on the idle mixture. I'm not saying this is a modification that has to be made. You can run the engine just fine without any carb spring modificaton. However, it helps with reaching a constant low idle. So it all boils into wether you want to have an engine that runs just fine or wether you want an excellent engine. In my very humble opinion the FA-125 has more potential than the stock set-up provides. Hence this modification. And by the way I think there is an analogy to the widely spoken CDI option in this carb spring thing: You do not need a CDI in a 100-150 size Saito but it does gives you some extra operational benefits. But to each his own, of course!

-Artto


-Artto
Old 08-01-2014, 04:58 AM
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Originally Posted by SrTelemaster150
Yep, no need for a throttle spring. I use the throttle trim to adjust idle & shut the engine down.

I also use it to reduce cylinder pressure so I can start large displacement engines (even my FA-300TTDP) W/a 90 sized electric starter. I only use the starter for he initial start if the day.

After the fuel system is primed & the engine warmed, I flip start.

Are we talking about the carb barrel spring or the throttle spring?
Old 08-01-2014, 05:40 AM
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Dave's talking about the carb barrel spring.They are totally necessary if you don't want to chase the idle around all day,all mine have them.
Old 08-01-2014, 06:27 AM
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Originally Posted by Old Fart
Dave's talking about the carb barrel spring.They are totally necessary if you don't want to chase the idle around all day,all mine have them.
OF, I share this opinion of yours. I actually wonder why on earth the Saito FA-125a is the only engine in range without the carb spring! But like said earlier it seems the engines released after FA-125a are going to have the carb barrel spring again. (i.e. FA-115)
Old 08-01-2014, 07:40 AM
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Aerofinn, your 125 sounds like mine.

Dan, this is an RCU issue as my iPad suddenly shows fonts as almost too small to read. I've sent a couple of messages about it and was asked to test the button navigation problem.

Low idles are nice if they are reliable. I have a 72 that would idle at 1900 with a good transition. But, I sometimes sit and do touch and gos and it did die on me on an approach, so I bumped it back up to around 2100 rpm. W8YE has a 56 that you couldn't even hear when he did approaches. He wouldn't tell me how low it was, but I would guess much lower than my 1900 rpm. His never quit and he sat there and did tank after tank of touch and gos as the sun went down.

The 125a has its own personality as compared to other Saitos.
Old 08-01-2014, 09:38 AM
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Here is my 2.20 idle it has no barrel spring, 1,830 if you can't see it.
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Old 08-01-2014, 09:45 AM
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Hey whats a replacement for an OS 52 and 70? I have a T-Clips 70 in the way soon and its time to look for a power plant. I was thinking of dropping a Magnum 91 on it, but I think it would be too much for it, it calls for a .65 FS. I might build another LT-40 with a modified to the hilt wing, and would like to put a Saito on it.
Old 08-01-2014, 12:58 PM
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Originally Posted by Hobbsy
Here is my 2.20 idle it has no barrel spring, 1,830 if you can't see it.
Dave,

very well, I'm happy this 2.20 of yours idles well without carb barrel spring. Have you actually checked yours that it really does not have the carb barrel spring? It should have one. Saito part #SAI120S90A. This is listed in Horizon Hobby FA220A parts listing.

-Artto

Last edited by AeroFinn; 08-01-2014 at 01:04 PM.
Old 08-01-2014, 05:05 PM
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Artto, we'll have to ask OF, I no longer have the 2.20, he'll know. I had two carbs for my 2.20 and I don't think either had a barrel spring.
Old 08-01-2014, 06:05 PM
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Here's my new 125a getting it's first taste of fuel. Check out the condensation on the intake!
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Old 08-01-2014, 07:01 PM
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Originally Posted by Hobbsy
Artto, we'll have to ask OF, I no longer have the 2.20, he'll know. I had two carbs for my 2.20 and I don't think either had a barrel spring.
Dave it's possible yours never had one on the earlier version? i'll attach some pix.
You can't see much of the 115 but there it is in a cmpro midget mustang.I hav'nt flown it for a while and it's been hiding in a dusty corner..flame me about it
ps a couple of flying mates uncharitably call it the red lawn dart.
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Old 08-02-2014, 06:26 AM
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Since I have examples of both the "standard" & optional DA-220 carburetors in question, I went out to the garage & checked. The "standard" 11mm carburetor for the FA-220 Is exactly the same as the FA-180 right down to the throttle barrel spring. It even has the same part number. It will spring back slightly from a closed position when released.

The 12mm "big bore" carburetor for the FA-220 does not appear to have the throttle barrel spring as it does not spring back from a closed position.

When the throttle is connected to a servo, whether or not it has a spring is a moot point as the throttle servo will hold the throttle barrel at any given position. Only if there was severe wear on the screw or throttle positioning groove in the throttle barrel could it have an affect on idle.

Last edited by SrTelemaster150; 08-02-2014 at 08:45 AM.
Old 08-02-2014, 08:13 AM
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Aw Dan, you put me in an aweful position, was I half right or half wrong?
Old 08-02-2014, 08:49 AM
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Originally Posted by Hobbsy
Aw Dan, you put me in an aweful position, was I half right or half wrong?
You were completely wrong about the standard carburetor & completely right about the 12mm big bore carburetor. Your posts canceled out & therefore do not exist.
Old 08-02-2014, 09:28 AM
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Originally Posted by SrTelemaster150
You were completely wrong about the standard carburetor & completely right about the 12mm big bore carburetor. Your posts canceled out & therefore do not exist.
wau..I see..
Old 08-02-2014, 09:44 AM
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Originally Posted by SrTelemaster150
Since I have examples of both the "standard" & optional DA-220 carburetors in question, I went out to the garage & checked. The "standard" 11mm carburetor for the FA-220 Is exactly the same as the FA-180 right down to the throttle barrel spring. It even has the same part number. It will spring back slightly from a closed position when released.

The 12mm "big bore" carburetor for the FA-220 does not appear to have the throttle barrel spring as it does not spring back from a closed position.

When the throttle is connected to a servo, whether or not it has a spring is a moot point as the throttle servo will hold the throttle barrel at any given position. Only if there was severe wear on the screw or throttle positioning groove in the throttle barrel could it have an affect on idle.
Dan, what you say sounds very convincing. I can assure, however, that when in idle the barrel does not rotate as this is prevented by the servo provided with the linkage is appropriate. The barrel can still move back and forth in the carburettor body as the engine vibrates. In actual operation this may or may not have effect on changing idle mixture. In some installations it is like if you screw the LS screw in and out.

Further, I think there is a reason why my OS and Laser engines all have the barrel spring. And generally speaking, all the recent Saitos have the spring.

I do not want to make this a big thing so this is just how I see the matter. I am happy to stand corrected if I am wrong.

-Artto

Last edited by AeroFinn; 08-02-2014 at 12:09 PM.
Old 08-02-2014, 04:34 PM
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Originally Posted by SrTelemaster150
You were completely wrong about the standard carburetor & completely right about the 12mm big bore carburetor. Your posts canceled out & therefore do not exist.
That sir is a real good one, I see too.
Old 08-02-2014, 05:26 PM
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Artto i don't think you are going to stand corrected on this point,thank you for taking the time to explain why saito fit that spring.Dave on any of my saito's,even when new,you can feel a little sideways play in the throttle barrel,it's quite normal.When you are bench running or tuning in the field with the engine running,you can lightly touch the low speed needle with a flat bladed screwdriver and without turning it get a noticeable change in rpm.That's why saito put's that light spring in there,it is just strong enough to hold the throttle barrel out on one side of the groove.You don't need to have excessive wear as has been stated here,it's how they come from the factory.

Artto is quite right in the way he thinks about it.

ps way back i pulled one of those springs out of an 82 to have a better look at it.Lost it but flew the next day anyway,idle was all over the place.Ordered a new spring and when it arrived i found the old one so now... a question?? did one cancel the other out ? did i ever lose a spring ??

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