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Saito 100

Old 05-22-2007, 10:15 PM
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jwander
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Default Saito 100

I have been batteling this engine on a Hanger 9 Spitfire Mk. II for many hours and am just about at the point of throwing in the towel. It is impossible to get a consistent idle.

I returned the engine to Horizion to be checked out because of excessive fuel pouring out of the carb when the high end was set at the factory specs. I requested that it be tested in the same configuration as the engine was in the Spitfire. That would be inverted. I was told after it was returned that all settings were to rich and the engine ran fine. I found out later that it was tested in the upright position which proved nothing because the problem persists. I was also told that this was the only problem they have heard of. Oh. Yes I did loop the carb feed line above the top of the tank.

Does anyone have any idea what I am dealing with? I estimate my associates and myself have spent at least eight hours trying to get this engine to run. Believe it or not we have gotten one flight in. I am at the point of throwing the towel in and saying I have had enough. I have been building and flying models for sixty seven years and have never run into a problem like this.

I thought I had seen it all until I was getting ready to disassemble the plane and found the left retract was hanging up on the wheel well. Really great for a plane that had not been flown today.

I would be glad to hear from anyone who may be experiencing similar problems or has possible solutions. I am using 10% four stroke fuel and am using an OS F glow plug. No I do not have an onboard glow driver.

Horizion says I am the only one who is experiencing these problems. I find this hard to believe.


Frustrated and tired.

Jim
Old 05-22-2007, 10:31 PM
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alan0899
 
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Default RE: Saito 100

G'day Jim,
The main problem with running engines inverted, is tank height, the centre line of the tank MUST be level with or no more than 3/8 (10mm) below, the main needle valve, or fuel nipple.
The engine does not care which way it is facing, as long as it is properly run in, & tuned.
Check out this site for (1) prop sizes, http://saito-engines.info/prop_sizes.html
And (2) throttle setup & tuning, http://saito-engines.info/throttle_setup.html
Valuable info.
Old 05-22-2007, 10:35 PM
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aussiesteve
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Default RE: Saito 100

My 1.00 ran like a total Dog when I first got it - I nearly threw it away after about the second gallon had been through it - couldn't get a good idle, lack of performance, fuel spitting etc.

Then I decided (after some advice given here) - to get really aggressive with the neddle settings. I put it on a test stand, set the HS to about 300 below max rpm, then started winding in the LS needle - it took a lot of turns in (about 5 turns by memory) before I found a difference but what a difference it made. I then followed the normal tuning procedure of high speed needle to about 300 rpm below maximum, 1/8th of a turn at a time on the LS until it transitioned right and the pinch test gave the right results, then another setting of the HS needle - Now it doesn't spit, runs smoothly at idle and transitions well - it now lives on a MoJo 60 with a 16/4 prop and 15% Nitro fuel and I love it again.
Old 05-22-2007, 10:49 PM
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jwander
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Default RE: Saito 100

Thanks. I hear what you are saying but the tank location in the Spitfire is already set. Unfortunately it's about 1/2" above the carb. That's the design.
Old 05-22-2007, 11:18 PM
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Default RE: Saito 100

G'day Jim,
And that's part of your problem.
Old 05-22-2007, 11:57 PM
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Default RE: Saito 100

I have a Saito 100 installed inverted in a H9 P-47, the tank is a little high in this plane as well. I've found that the engine runs fine IF you have the low speed needle leaned sufficently(sp). Do what aussiesteve said and you'll see that the Saito 100 really is a great engine. Due to the higher tank position I make sure that I don't fuel the plane intil I'm ready to take off. I do this to reduce siphoning that can occur with a full tank.

I guarantee; get it tuned right and you'll love this combination. Good luck.
Old 05-23-2007, 12:22 AM
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Harry Lagman
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Default RE: Saito 100

JWander - what the other guys have said - especially Aussie Steve.

I have got the Saito 100 in an H9 Mustang so its tank position is probably very similar to yours relative to the engine. My engine has a very reliable 1800 - 2000 rpm idle. Check the tappets, use a fresh OS Type F plug, fresh fuel and let's start working on those needles...

With many inverted engines, you MUST get the idle mixture absolutely as lean as you can get away with before your idle and transition to high throttle settings start to deteriorate. On a Saito, that means many turns in from where it was when you pulled the engine out of the box. You will never damage an engine with a lean mixture when it's idling.

There is no such thing as a "factory setting" on a model engine - this is the single most misunderstood issue in the history of aeromodelling! There are guidelines on where to start but every engine's low speed and high speed needle must be adjusted to where that particular engine runs best in that particular airframe with that particular fuel.

Good luck and do report back.

Old 05-23-2007, 08:21 AM
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WMB
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Default RE: Saito 100

"There is no such thing as a "factory setting" on a model engine - this is the single most misunderstood issue in the history of aeromodelling! There are guidelines on where to start but every engine's low speed and high speed needle must be adjusted to where that particular engine runs best in that particular airframe with that particular fuel. "

So true and the cause of much frustation.

If the tank is too high in the fuse, could a smaller tank be used to lower the 'head' seen at the carby? Might be worth a try if it will get you into the air and get time on the engine. After break-in go with the original tank if needed.

My 65 is inverted and idles low and slow. Runs great on 10%.
I could never get my 45 to idle like the 65, but running 30% sure does help. The 45 is still low time so I'm hoping it will smooth out with more time on it.

Good luck, MikeB
Old 05-23-2007, 12:01 PM
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blw
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Default RE: Saito 100

Saito engines do come with a recommended setting for the low speed and high speed needle valves. HS needles are specified with so many turns rich, and LS needles either flush or a certain amount below flush with the throttle arm.
Old 05-23-2007, 01:47 PM
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rc-sport
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Default RE: Saito 100

I think RCU should post a How To Video on tuning 4 strokes, it seems so many pilots have absolutely no clue on how to tune a 4s. I had a good mentor when it came to tuning 4s and all my engines are inverted and run like a swiss watch. I don't know much about fixing them but I can tune quite well.

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