rcuser004

My Feedback: (287)

The problem is the engine is adjusted too lean. However, I assume you can continue to back out the main needle until it is ready to fall off and you still cannot get it to run rich. The problem is the adjustment of the idle mixture needle. Supertigre engines have the same problem.

If the idle needle valve is screwed in too far, it can reduce the amount of fuel metering out of the spray bar and into the engine. It then limits the amount of fuel the main needle can allow into the engine. Close the main needle completely and then back it out about 5 turns. Start the engine and advance the throttle to full. Try backing out the main needle further. However, if the richness does not change, return the adjustment to "5 turns" out and bring engine back to idle. Back out (richen) the idle mixture screw 1/2 turn. Advance the throttle to full again and see if the engine is running any richer. Back out the main needle to see if you can richen the engine. You need to be able to back out the main needle until the engine runs overly rich. If you cannot get an overly rich top end, repeat the backing out of the idle needle 1/2 turn at a time until you can create an excessive rich situation with the main needle at full throttle. Once you acheive this, adjust the main needle properly, bring the engine back to idle and then you will need to adjust the idle needle (screw it back in to lean the idle mixture) to acheive a proper idle. However, don't screw it in so far as to affect the top end again. The proper running is achieved by compensating between the idle and main needle valve adjustments. The problem lessens as the engine is fully broken in.

Good Luck...

bfreee

To all, thanks for the help guys, found out some very interesting things. A friend of mine works at a plant where they have a meter that will read pressure, vacuum, ect. down to 1/100th of a psi. He brought that home & we hooked it to the pressure line from the muffler to the tank with a Tee. We found that we got no pressure at all until we went wide open & then it was .02 psi. We knew we had a problem right away. Got the cowl off for the 20th time & started looking carefully. We found two things wrong. One was the pressure nipple in the muffler had worked loose. It still was in place fully, it just would turn if your twisted the hose, Secondly, we found a small cut in the pressure line right at the pressure nipple. Very small & undetectable until you pulled on the hose. We replaced the lines, re-loctited the pressure nipple & ran it again. We found that the engine made NO pressure at all at an idle. This would explain why it is so important to have the tank 5mm or less lower than the spray bar per the manual. If you have the tank any lower, the engine would not be able to draw the fuel to the carb. This is a fact. The engine does actually suck the fuel to the carb at speeds lower than approx 3-4 thousand rpm. As we sped the engine up, the pressure increased smoothly to .5psi maximum at full throttle. This will lift the fuel easily more than a foot. The system actually works very well as I guess every happy running engine knows by exhaust pressure. As the rpm's increase, so does the fuel pressure, which is exactly what the engine needs. No need for the pump. I would go as far as to say that the fact that a pump applies a steady even pressure through the whole rpm range is not how these carbs are really set up in these engines. Its obvious that the two needles give you lattitude hear, but as in any engine more fuel is required at higher rpm. This because you do not have the extra pull coming from the vacuum applied to the spray bar that you have at idle & part throttle. This vacuum helps draw fuel in. When you open the throttle above part throttle, the vacuum is lost, therefore an increase in pressure is needed. This is the same principle that is at work with a fuel pressure regulator on a modern fuel injected car that I work on everyday. In a car, vacuum is applied to the nozzle of any fuel injector that is below the throttle plates (read in the manifold), this low pressure area makes it easier for the fuel pump to spray its fuel into the manifold, therefore they use a regulator to decrease the fuel pressure when high vacuum is present. When the vacuum disappears (read wide open throttle) more pressure is needed to achieve the same fuel delivery. There are other factors at work here, but this is the basic premise. In the end, my problem was all created by me, and the fact that when you only have a half a psi of pressure, you cannot afford to lose any of it. Always check your pressure lines any time you have a lean/stalling problem. Be very careful handling silicone tubing, it loves to split!!!!!!!!!!! I hope this helps someone. Basically, the only thing I found out is that I had everything setup right from the begining & just had some small leaks that weren't apparent. Thanks again to everyone that helped me. I stuck it out & finally found the problem like BobPhx said, it would be worth it when I figured it out. In the end it was the simple things!! Thanks again.

Kmot

My Feedback: (24)

Fascinating reading bfreeeeeeeee, thanks!

BobPhx

WooHoo!
Glad to hear it worked out.
One more tidbit: I struggled a lot with the stock pressure tap. Mine was in thin aluminum on the muffler, and would come loose or strip. Tried everything I could think of, including JB weld. Finally went to the pits anyway, liked the look and sound better, and got a better pressure tap connection in the process.
When the pressure tap would come out in flight, the motor would not advance above half throttle, and would die if I went vertical. Fortunately I learned to recognize it after one deadstick and the next couple of times it happened stayed below half throttle and landed.
Point being, make sure that sucker is in there. Flameouts suck.
Bob

kaastrup

I got a Saito 72 installed in a Funtanas 40, I use Coolpower 15% heli mix, and APC 14x4W. I get around 9000 rpm and I think thats fine and enough. I would say your engine is run-in at ½ gallon or 6-7 tanks, it should not take any longer. But I don't think you will ever get 9500 rpm with that prop.

kaastrup

Anybody.....Saito 100, Coolpower 15%, APC 14x10 and 8500 rpm.....Is that OK or is the prop to much. The setup is for a TWM Groovy 90 F3A.

dmcmike

My Feedback: (14)

ok, i've lurked around on here long enuff! Count me in Club Saito as the proud owner of an original FS-80 from Way Back, and a GK-100 which is currently pulling my Hog Bipe around the sky like a homesick angel! There's been others along the way, but these are the two i'm currently using. What a great thread.

Sturtz

My Feedback: (20)

Got my Saito .72 back from Horizon/Saito last week and thought I'd report the problems they found and fixed .
Replaced the front and rear bearings. They believe the reason for my over heating was caused by the prop hub rubbing into the front of the crankcase. Tom replaced the tapered collet and reinstalled the hub. Problem solved.

beausol

My Feedback: (18)

Bfreee....

I saw in my manual where Saito says to mount the fuel tank 5mm lower than the carb center, but is that the CENTER of the tank (ie where the fuel line comes out) or is that the BOTTOM of the tank?

Based on what you reported, I don't need a pump for mine.

Thanks!

--Rich

bfreee

Hey Rich,

I've always wondered about this myself. They are unclear about this but I believe from what I read that everyone goes from the center of the tank. The reason being is that at anytime, the most you could be off is only half a fuel tank. An easy way to determine the height is to fill your tank half full after you have it where you want it. Now this can be half full on the landing gear or prop the tail up to a level stance. It doesn't matter much. I do mine on the gear so it will be set for taxi-ing. Hold your line that goes to the car low, blow a little air in the pressure hose. This will start a siphon. Now hold the hose end upright & slowly move it up toward the level of your spray bar. When you reach the point that the fuel stops flowing, this is the equal level point. Your spray bar should be 5mm higher than that. This 5mm is somewhat forgiving, just try not to make the tank much higher than 5mm lower. This is how I've done my others & this is how my 180 is now. Some others might now for sure what Saito means by this, but I'm sure this is right. Yes, you should not need a pump, if you do, something is wrong, that's what I found out the hard way. Hope this helps

Bruce Freeman

Ghostrider FIN

I have also Saitos. They are just great. FA-300TL, FA-82 & FA325R5 Do you count me?

LordSirOb

Thanks for the info. I had it out again today, and after two more flights my 72 is peaking around 8800 rpm. It just keeps getting stronger. I just think I need to be patient awhile longer...

SigMan

My Feedback: (21)

WOULD THE SAITO 125 BE A GOOD MATCH FOR THE HANGAR 9 P-47 ?

OR BE TO BIG FOR IT ?

SigMan

My Feedback: (21)

OR BE TO BIG FOR IT ?

blw

My Feedback: (3)

SirOb,

You should be getting more RPM out of your .72 at some point. You really don't need 30% fuel. I only run 15% Omega as it has castor. I'm using an APC 13x6 and I'm somewhere around 10,200 after richening from peak, depending on weather. I have measured it at 10,400 on cooler days.

Have you set both needle valves yet? You mentioned having run 3/4 gallon of fuel. How much fuel do you think it is burning in a 10 minute flight? That should tell quite a lot there as to the needle settings. The engine isn't completely broken in yet, so keep flying it. By the way, how is your idle? You didn't mention that.

gjeffers

thats a 15lb plane isnt it?
maybe a 180 or 220[8D]

gjeffers

opps, you must be talking about the 60 size[&:], my mistake, i would say it would be a great engine for the plane

LordSirOb

Actually, I think I was having some tank/plumbing issues that was affecting the motor. I had a deadstick that was the result of the fuel pick up line in the tank coming off the brass tubing. Luckily, with a profile, everything hangs out and it wasn't too long before I found the problem. Anyway, once the tank problem was recified, and the saito plug exchanged for a OS F, the motor came alive. I am still running rich on the low end, and rich on the high, but now it is pulling much stronger adn the transition is ok for now. I'll start tuning for performance in another 1/2 gallon or so.

Just to be on the safe side, I replaced the entire fuel tank with a new one.

blw

My Feedback: (3)

You could probably start leaning out your needle valves already to close to optimum. The engine will get better and more efficient as you put time on it. The LS needle valve will then need setting to get it just right. You may see fuel economy get a little bit better in the next gallon or so.

FFOURU

My Cub took a cartwheel, and when I started to repair, I found more damage than I want to deal with. I just ordered an Arrow 40 trainer with the idea of putting my 72 on it. I can't find any info on what 3 blade prop would be good for a 6 lb trainer with the 72, any ideas?

JettPilot

My Feedback: (6)

Forget the 3 blade prop, they are inefficient and perform poorly for that application. Get a 2 blade APC , that is about the most efficient and best performing prop you can put on that engine.

JettPilot

My Feedback: (6)

Here is a SWEET engine I just flew it for the first time yesterday, it runs great and flew great, but I am having an issue. When I try to start it with a chicken stick, it kicks back so hard every time I broke the stick [X(]. Sometimes it just kicks back, but sometimes it starts to kick back and fourth and does that for about 15 seconds before quitting. If I try to flip it backwards, it never fires while flipping backwards, but will fire every time flipping fowards. Any ideas on how to get this engine started ?

Thanks,

JettPilot

w8ye

My Feedback: (16)

Sullivan Dynatron starter

strulag

My Feedback: (-1)

I have a 150 as well. The bad part is that these standard starters (even the TorqueMaster 180) are not strong enough to flip'em. This engine (and it seems saitos in general) likes it really wet when you start it. This is how I first start mine and it works very well: Cover the muffler end, and flip the prop 5-7 times while at high idle then flip it a couple of times without covering the muffler and stop right after the compression so when you push it backwards it's right against it. Stick the headlight and just flip it lightly backwards against the compression. Mine starts the first flip. I don't even use a stick or anything.

P.S. When I say flip 5-7 times, I mean 5-7 times through the compression not just rotations. Let me know if it works for you as well.

FFOURU

Well, you see there is a ground clearence problem with the proper size 2 blade, and if you buy the RTF version, it comes with a 2 stroke and a 3 blade. I have also been told that they use the 3 blade on trainers to sort of de-power them for the learning experience. The 72 maybe be over powered in the Arrow 40, so I don't think I need to get all the go from it anyway.

I am not a complete beginner, flew a Goldberg Cub on floats for a couple of years, but that was about 12 years ago. I just crashed my Cub flying on wheels, ( I know, should have been flying with an instructor), and decided that I needed to re-learn, hence the Arrow 40 purchase. I have 2 other airplanes, (in addition to my crashed cub) a TF 60 Corsair, and a TF 182 Cessna, too much time and money in them to re-learn flying/crashing with those birds. I'm holding them in reserve until I have my thumbs working better. I did join a local club, and I will get with an instructor to re-learn on the Arrow.

But, I want to find out what size 3 blade would be good for this ariplane and my Saito 72!