Crash90

My Feedback: (17)

What is a good rpm range for a saito 72 at idle?

David Cutler

My guess would be around 2200 rpm, but whatever it is, it should be slow enough just to avoid the model moving.

-David C.

WhtBronco

Sure wish mine would idle slow enough to not move. I have better than a gallon through my Saito 72 and it still won't idle lower than 3500 reliably without the glow plug igniter. I hate this engine.

Richard L.

My Feedback: (24)

Try leaning out your low end and lower your throttle trim. Also try a new OS Type F glow plug. Some Saito .72's do not achieve low idle speed until after the third gallon of fuel.

bgi

My Feedback: (7)

What kind of prop are you using? The APC props should get down to 2000-2200 or so with a proper idle mixture.


(added...)

AND OS F plug AND proper valve clearance AND good fuel AND break-in....

David Cutler

I betcha an new OS F type plug will solve this problem . . that and a few more tanks of fuel through it.

Don't be afraid to lean out the idle screw, especially if you are finding it either 'bumps' on idle, or, as you say, it doesn't like the glow igniter taken off.

Suddenly I think you'll find it is a dream to run.

-DC

Hobbsy

My Feedback: (102)

When the low end is set right it will idle exactly the same on a Fox Miracle plug, Hangar Nine Super plug or an OS-f, there will be no difference.

WhtBronco

Thanks for the reply's all. Here's what I have done with my Saito 72 so far. Tried 2 new OS Type F plugs after 4 tanks with the McCoy/stock plug. APC 12x8 and 13x6. Today I spent another 90 minutes trying to get the idle needle set correctly. What I found was when I first fired it I let it run for 3 minutes to warm up before doing anything. Then I slowly advanced the throttle off idle. It was idling fine with the plug igniter fine. So I went back to idle and then tried revving it quickly, no probs. Took the igniter off and the idle dropped a few hundred rpm. Then it slowly started to idle lower and lower and died. I restarted it and tried to rev it and it sputtered/hestitated on 3 atempts to rev up with the igniter off. So I leaned the low end 1/8 turn. Repeated. After I did this 5/8 turn in total I found the engine died immediately when the igniter was removed so I richened the low end 1/8 turn. It idled fine on the igniter, but hesitated on rev up again. I checked the fuel level, 1/2 tank still. Changed the plug. Same problem. Checked valve lash, set to about .04mm. I fired it again with the same result only ran well with the igniter or at 3500+ rpm. Then I noticed the even left at 3500 rpm the engine would slowly, took 2-3 minutes, lower idle and die. Tried several more starts with the same results even leaving it at 5000 rpm. Got angry and put the plane away.

I have noticed it rus a bit smoother witha full tank so I wonder if it is foaming due to vibration. Unfortunately there is little I can do as the tank is already packed in foam but does rest against the firewall and a fuse bulkhead.

The plane has been ready for 11 weeks now, but I am not going to fly it until the engine is reliable. At 3500 rpm the DPM Ultimate 40 will fly quite fast I think, too fast to land. If I am lucky I get 1 day a month to fly, so this engine is really getting on my nerves. I am gonna give it 2 more sessions to run reliably, about another 1/2 gallon on top of the 1+ gallon through it so far. If that doesn't do I will sell it and get an OS 50SX. This is the first engine in 20 years that has been a real problem for me, it's also my first 4 stroke, and almost certainly the last.

David_Moen

I'll take it off your hands Bronco! Swap you for a near new 46FX!

David Cutler

It sounds as if there is air getting into the mixture other than through the carb.

Check to see if the 'O' rings at either end of the intake tube are seating properly and are not damaged.

Also, see if the plastic crankcase cover at the back (where the carb is mounted) is damaged or cracked.

Of course, there could also be dirt in the needle. While you are checking the 'O' rings, clean out the carb.

Good luck! It may be difficult to see right now, but Saitos really do run well. Honest!!

David C.

Gunthr

I was wondering what fuel you're using?

I'm breaking in a new Saito 40a that idles at 1900 - 2000 without the igniter on and I haven't yet set the high or low speed needles yet. I'm using Sig 15% nitro and 20% oil. I read somewhere that the low end in Saitos benefit from the nitro...

G'luck

Crash90

My Feedback: (17)

WhtBronco. Is the engine mounted inverted? Just curious.

I have mine inverted on an US40+. I built it according to the plans and with my engine inverted the whole tank is above the carb. I hope this doesnt cause any problems. Only have 2 tanks thru it so far. We shall see.

WhtBronco

Thanks for the info guys.

David_Moen I have no in interest in a 46, thanks though.

David Cutler: I had thought about an air leak while toying with the engine yesterday, but forgot before I was done to check it. I'll take it apart this morning and check it out and clean it.

Gunthr: I am using 15% Cool Power.

Crash90: My engine is monuted on it's side and the tank centerline is about 1.5" below the carb fuel inlet. Your tank being above the carb shouldn't cause any probs. I used to intentionally set up my control line planes in that manner.

Crash90

My Feedback: (17)

Since you are having the same problems as I am. Please keep me updated. Thanks

bgi

My Feedback: (7)

That doesn't sound too good.

Questions:

Have you run the engine on a test stand setup with the tank at the same height as the carb inlet?

What would you want in a trade for it?

fossil

My Feedback: (25)

Don't trade the engine, mine took about 2 gallons of fuel before it would idle right, I just kept flying and adjusting. I know it is a pain and I almost got rid of mine also, but then it just comes around and was the best running engine I had. It would idle at about 1800 on the tac. Then I traded it for a Saito 100 and I am going through the same with it, but its starting to come around. A high Idle makes taxing a pain but landing should't be that big a problem.
fossil

bgi

My Feedback: (7)

Fossil, I found myself arguing on your side with respect to the TT 91 FS. But my Saito 72 was all tuned, tweaked, adjusted, and running fine with a reliable 2400RPM idle after only about 48 oz of fuel.

You guys with the engine problems: I do think you should get the engine running well on a test bench BEFORE you mount it on a plane. Like you, I only get about 1 flying day a month. I refuse to waste that day tinkering with engines at the field. So I ALWAYS get the engine problems solved at home. Put it on a test stand with the proper tank height and get it running right - should be very easy there. Once you do that, after you mount it on the plane, you KNOW the engine ran well so you KNOW that the list of possible problems is short: I bet it is that 1.5" fuel draw.

-brad

PigMan Buggerus

My Feedback: (6)

Add my vote to running in on a stand. I broke both my Saito 100's in on a bench. They both drank a gallon of fuel before they ever saw a plane.

Hobbsy

My Feedback: (102)

I don't know what we do differently but I have 10 Saitos and all were ready to fly after 30 to 45 minutes, I think the 100 would have been alright after about 15 minutes.

bgi

My Feedback: (7)

I don't believe the buggerman piggus stated that the whole gallon was required. He just said that a gallon was used.

David_Moen

I was only kidding about the trade BTW

bill white

My Feedback: (13)

I have 2 Saito 72's, and they both run great, Iidle at about 2000), however the break-in time was long. Also I discovered that the location of the tank is critical, ( approx. 1/4 " above the CL of the carb.) these engines do not like to draw fuel up-hill. The other plugs that have been mentioned are probably OK, but I have had good luck w/OS F plugs, and will stay w/them.

Hope this helps, Bill

PigMan Buggerus

My Feedback: (6)

Gallon probably isn't required, but after running a gallon, changing plug, and adjusting valves, I have had zero problems.

David Cutler

That's been my experience with my 2 Saito 72s and one Saito 100, except the 100 flew straight away having screwed the idle needle in about 2 turns when I first tuned it.

-David C.

Crash90

My Feedback: (17)

Well. I only have 2 tanks thru it so I will be patient. I'm so use to OS engines. Take them out the box and fly them.

That being said. I love the saito. Cant wait till it is broke in.