Saito 100 Props / RPMs
09-06-2002, 06:31 PM
#26
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Saito 100 Props / RPMs
I don't know, maybe I'm running too rich, but I'm getting over 10,000 peak with an APC 15 - 6 and back off to about 9800 which seems as good or better than anyone else, so it can't be too rich
My answer to the above questions were yes and yes. For about a month my engine ran fantastic on the hi-end but I had to battle the airplane on the ground and during landings because I couldn't get my idle low enough. It was ok because it forced me to get real familiar with the plane before I started doing anything but simple aerobatics. I attributed this to thinking it just wasn't broken in yet. One day a friend of mine, who has been running the Saito 150 and 180 help me analyze my engine -- by this time I was a little frustrated with the high idle and very bad fuel economy. When we were done the low speed needle had been turned in over 2 turns. But, what a difference. My idle is extremely smooth and just below 2000rpm with a Master Screw 14x8 Scimitar. But even more dramatic was the improvement in fuel economy. I easily get 12 minutes of flying and still have most of a half of fuel tank left (16oz).
Unless you are very familiar with these engines you might do what I did initially. I assumed the factory setting for the low speed needle was pretty close to optimum (this is usually the case with my 2 strokes) and would require very little adjustment. Because of this when I started to adjust the low speed needle and saw little to no improvement in even a half to full turn I reluctantly stopped trying to adjust and lived with the high idle.
BTW, I also have this engine on an Ultra Stick 60. I just recently switched out the 2.75" wheels for 3.5" wheels and changed out the 14x8 Master Screw Scimitar for an APC 15x6. What a difference. The idle noise is virtually non-existent and the upturn is significantly improved. The only thing I'm battleing right now is the idle again. Even with a few clicks more in the idle direction -- right at the point it goes from smooth to jerky, the thrust from the prop is still too high to keep the airplane stationary. It looks like the low speed needle needs some more adjustment. (BTW, I haven't yet tached it since I changed out the prop.)
09-06-2002, 06:34 PM
#27
Saito 100 Props / RPMs
Originally posted by lnorris
Um, I think you mean elevation which was what Blackie was talking about. Distance from sea level.
Unless you do mean lattitude which would mean that the farther you get from the equator, the better your engine runs...????
Um, I think you mean elevation which was what Blackie was talking about. Distance from sea level.
Unless you do mean lattitude which would mean that the farther you get from the equator, the better your engine runs...????
Location: Nunavut, Canada.
Higher the lattitude, the colder the climate, the better the engine runs!
Don't you ever listen to Jimmy Buffet? Changes in lattitude?
09-06-2002, 07:06 PM
#29
Saito 100 Props / RPMs
A well designed carb and venturi will self adjust the mixture to a certain extent. A denser charge of cold air will cause a larger pressure change and pull in more fuel, add the couple of clicks richer and it could be a considerable amount of fuel. It would account for his increased performance also. I don't think its the factory settings. He stated he timed his engine at full throttle with the engine richened up 200 RPM below peak.
09-06-2002, 07:49 PM
#31
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Cold dense air
If you set an engine for warm air and then expose it to cold dense air it will go lean due to more oxygen being available and the fuel flow being physically limited by the needle valve which was previously set for warm air.
09-06-2002, 08:04 PM
#32
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Location: Nunavut, Canada, Above the Arctic Circle
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Saito 100 Props / RPMs
I have really started something here eh ! Anyway I don't run this engine in Nunavut, Hell the last time ( about 5 years ago ) I got some prices on bringing in glow fuel it came out at about $75.00 per gal with freight, dangerous goods charges etc. Potatoes here are $18.00 for 10 lbs. I just work here and fly for a few months R & R in Nova Scotia which is sea level, but not nearly this far North.
I've turned the idle screw in about 1.5 turns or so and am getting a 2200 rpm idle with an inverted engine and no heat. No I guess I'm just too chicken to lean out the high speed needle anymore. I'm stuck here in "The Great White North" until next May so I'll pick up where I left off at that time and try some of your suggestions then.
Enjoy your warm weather boys ! Right now it is -3 C and snowing her.
I've turned the idle screw in about 1.5 turns or so and am getting a 2200 rpm idle with an inverted engine and no heat. No I guess I'm just too chicken to lean out the high speed needle anymore. I'm stuck here in "The Great White North" until next May so I'll pick up where I left off at that time and try some of your suggestions then.
Enjoy your warm weather boys ! Right now it is -3 C and snowing her.
09-07-2002, 02:06 AM
#33
Re: Cold dense air
Originally posted by hobbsy
If you set an engine for warm air and then expose it to cold dense air it will go lean due to more more oxygen being available and the fuel flow being physically limited by the needle valve which was previously set for warm air.
If you set an engine for warm air and then expose it to cold dense air it will go lean due to more more oxygen being available and the fuel flow being physically limited by the needle valve which was previously set for warm air.
01-03-2021, 05:22 PM
#35
Real answer
Here's a thought. You may be looking at the wrong adjustment. Saitos, especially this one, the FA-100, come from the factory adjusted for breakin performance. What this means is the low-speed adjustment is super rich. Ask yourself this question: Does my engine idle extremely low and very smooth? -or- Does my engine tend to break up if I try to adjust the idle much below 3000rpm?
My answer to the above questions were yes and yes. For about a month my engine ran fantastic on the hi-end but I had to battle the airplane on the ground and during landings because I couldn't get my idle low enough. It was ok because it forced me to get real familiar with the plane before I started doing anything but simple aerobatics. I attributed this to thinking it just wasn't broken in yet. One day a friend of mine, who has been running the Saito 150 and 180 help me analyze my engine -- by this time I was a little frustrated with the high idle and very bad fuel economy. When we were done the low speed needle had been turned in over 2 turns. But, what a difference. My idle is extremely smooth and just below 2000rpm with a Master Screw 14x8 Scimitar. But even more dramatic was the improvement in fuel economy. I easily get 12 minutes of flying and still have most of a half of fuel tank left (16oz).
Unless you are very familiar with these engines you might do what I did initially. I assumed the factory setting for the low speed needle was pretty close to optimum (this is usually the case with my 2 strokes) and would require very little adjustment. Because of this when I started to adjust the low speed needle and saw little to no improvement in even a half to full turn I reluctantly stopped trying to adjust and lived with the high idle.
BTW, I also have this engine on an Ultra Stick 60. I just recently switched out the 2.75" wheels for 3.5" wheels and changed out the 14x8 Master Screw Scimitar for an APC 15x6. What a difference. The idle noise is virtually non-existent and the upturn is significantly improved. The only thing I'm battleing right now is the idle again. Even with a few clicks more in the idle direction -- right at the point it goes from smooth to jerky, the thrust from the prop is still too high to keep the airplane stationary. It looks like the low speed needle needs some more adjustment. (BTW, I haven't yet tached it since I changed out the prop.)
My answer to the above questions were yes and yes. For about a month my engine ran fantastic on the hi-end but I had to battle the airplane on the ground and during landings because I couldn't get my idle low enough. It was ok because it forced me to get real familiar with the plane before I started doing anything but simple aerobatics. I attributed this to thinking it just wasn't broken in yet. One day a friend of mine, who has been running the Saito 150 and 180 help me analyze my engine -- by this time I was a little frustrated with the high idle and very bad fuel economy. When we were done the low speed needle had been turned in over 2 turns. But, what a difference. My idle is extremely smooth and just below 2000rpm with a Master Screw 14x8 Scimitar. But even more dramatic was the improvement in fuel economy. I easily get 12 minutes of flying and still have most of a half of fuel tank left (16oz).
Unless you are very familiar with these engines you might do what I did initially. I assumed the factory setting for the low speed needle was pretty close to optimum (this is usually the case with my 2 strokes) and would require very little adjustment. Because of this when I started to adjust the low speed needle and saw little to no improvement in even a half to full turn I reluctantly stopped trying to adjust and lived with the high idle.
BTW, I also have this engine on an Ultra Stick 60. I just recently switched out the 2.75" wheels for 3.5" wheels and changed out the 14x8 Master Screw Scimitar for an APC 15x6. What a difference. The idle noise is virtually non-existent and the upturn is significantly improved. The only thing I'm battleing right now is the idle again. Even with a few clicks more in the idle direction -- right at the point it goes from smooth to jerky, the thrust from the prop is still too high to keep the airplane stationary. It looks like the low speed needle needs some more adjustment. (BTW, I haven't yet tached it since I changed out the prop.)
I know this an old thread but you may be looking at much later. The reason these people are using so much fuel is tuning. For some reason Saito engines will run very well with the low speed mixture WAY too rich. Once initial break in runs have been completed adjust the high speed jet like you normally would. Then you start cranking the low speed down till it dies on quick acceleration. Then back up till it doesn't. Dont be surprised if it takes a couple or several turns. When it is running great run it that way for a while. Factory spec for 100. 1 oz per minute wide open. I have 16 oz tanks I have never been able to outlast. In fact last summer the throttle let loose on my venture and 2 of us got fatigued from running it around full throttle till empty so it could be landed
01-03-2021, 07:04 PM
#36
The very rudimentary metering system tends to draw less and less fuel as the viscosity of the fuel reacts to dropping temperature.
Not totally equalizing, but the wide range of acceptable air/fuel ratio with methanol further marginalizes the effects of air density changes.
