I have a Saito 72 that runs sloppy-rich at mid-range and lean at full throttle and idle. I bought this engine second hand and I could not get it running right. I called Horizon and described the problems to them and in the conversation they informed me it had the wrong needle valve, spray bar and idle needle. I got those parts from them and installed them. Now I have the rich mid-range problem. When I called Horizon again the tech I got this time just wanted me to send it to them and also kept telling me to try 30% fuel. Well that is BS. I understand that the motor might have more performance with 30 % but that is not the problem here. I am running 15% Power Master in all my engines and all my other Saitos run fine with it. This 72 has a new rear bearing, the timing has been checked twice and the valves are set right, it has a new OS f plug and turns a APC 13x6 over 10,000 RPM. So I don't think it is "wore out". There are some things going on here that I don't understand such as the gap between the needles is around .040 at full throttle. Yet even at this much gap it still goes lean and dies before the barrel even gets down to the idle position, and is still rich in the mid-range. The high-end needle is open 2 1/4 turns. Another thing I have noticed is that the end of the spray bar is some-what smaller than the opposing end of the idle needle and as the carb closes and the barrel moves inward the end of the spray bar goes into the end of the idle needle and stops all fuel flow. I put a fuel line on the nipple, when I blow in the line as the barrel closes, before it gets to the idle position the needles overlap and the flow stops.
Can anyone suggest anything?
Thanks for any help
4 4 4 4 stroken ron

HEllo; We had a similar situation today at the field, it was a 70 surpass in a protege. I leaned out the low end 1/4 turn, took off and flew it for long enough to get it hot. I noticed that it was still smoking like hell when I advanced the throttle but would stop when it reach it's peak revs. I had a fun flight anyway when I landed it I went another 1/4 turn leaner on the low speed needle and two clicks richer on the main needle. The next flight was much better.
I don't have any first hand experience with that Saito but maybe there's something here you can use to solve your problem.

Ron
You either got something very wrong or you have a very different carb on your Saito 72 than I have on mine.
There should be no gap between the idle needle and the spray bar at any throttle setting. The idle needle (on mine) is a tube that slides over the spray bar, same as you discribe on yours.
My idle needle is 2 1/2 turns open and there never is a gap between it and the spray bar even with the throttle wide open. My high needle is 4 1/2 turns open and is only very slightly rich at full throttle. When the idle is correct it will be very difficult to blow air through at low throttle. By mouth it will seem blocked, but using a syringe (rubber bulb) you will be able to tell it's leaking.
It seems to me, without seeing the engine hearing it run, that you are very,very rich on the idle and lean on the high speed.

Thanks for the reply. Does your spraybar have a slot or a V cut in it in the area that the idle needle slides over it? The spraybar on mine is just a straight tube that sticks about halfway across the barrel and the fuel just sprays out the end of it.
Ron

4 stroken
Yes it has a cats eye slot. You have a mix of incompatable parts. Without the slot the tube type idle needle will just shut off fuel flow. With a straight dump tube spray bar you need a tapered idle needle. Looking at my engine, you have the wrong spray bar. The slot will be on the intake valve side of the carb so you can't see it when the carb is on the engine.
Denis

Yup you are right. I called Horizon this AM and talked to Derek. He sayes the same thing you are saying. I got a new spraybar coming. Thanks for the help. I would not have known the right questions to ask without your help.
Ron

Glad I could help. Good luck with it. Running right, you'll love that engine.
That engine of course runs just fine on 15% and will probably run good on 5%.
On 15% mine turns a 13/6apc at about 10200. On 30% heli it turns 10800 but doesn't run any better

Thank you guys!!!!! I pretty much have the same problem. Runs really rich in the mid range. So rich in fact that the motor runs real hot. Lean on top and bottom and to make things worse, The mixure changes drasticly from full to empty tank. I put a pump on it and that help big time. I would like to get ride of the pump cuse its heavy and its harder to prime the motor for the first flight of the day.

I have a satio .40 and it runs PERFECT !!!!!!!!!!!!!!!!!

Love that motor. Wish my 72 ran as good.

I will check tomarrow on the spray bar on the 72. (cross my fingers ) I will let you know how it goes.

Again, thank you!

I received the correct spray-bars from Horizon Saturday. I installed one of them right away. The engine ran perfect. I loaded up and went to the field and flew about 6 rounds with it. 10700 turning an APC 13X6 and still lot of smoke. Mid range is smooth and the idle is nice and smooth and slow. The transition is perfect Haven't had a dead stick yet.
I really like this engine now that it has the right parts.
Ron

Do you guys think that Saito is inadvertantly putting some of the carbs together with the wrong parts? What a dirty trick that would be.

I wonder why my 72 is happy at only 2 turns open on the main needle??? Some of you are running at 4+ turns open.......

Ernie

When you buy an engine second hand you don't know what you're getting even if you know the guy you're buying it from.

You are right. I bought this engine from a fellow here that had good karma and I really don't think he knew it was bad. My biggest problem was the first time I called Horizon I got a person that was less than knowledgeable about the engine. and sent me the wrong parts. I thought they knew what they were doing, which turned out to be my mistake and it took a member of this list to straighten me out. Thanks again Denis. The second time I called Horizon and talked to Derek He knew right away what the problem was and sent me the correct parts. Now the engine is perfect.
Ron

Ernie
Assuming your tank is on spray bar center line, and all other things equal, the difference in needle settings is just going to be tolerences in the parts.
Denis

Well, my tank is on center. :-)
4 4 4 4 stroken ron

Gee, looks like they built that whole plane just so the tank could be on the centerline.....:-)

Ernie