two questions...first and most importantly, when I have the motor revved to about 10000 rpm and cut the throttle to idle, the motor goes down to idle then "surges" for about 5 seconds up to 3500 rpm and then back to idle where it stays. I can only assume that my mixtures are incorrect. To the question, which one and is it too lean or rich?

Second question, I've got about a gallon and a half of fuel through my motor which is a saito 72, I have a 13x6 prop with omega 4 stroke fuel and an os plug. I can only get a reliable idle down to 2400, after that sometimes it stays running and sometimes not. Is that normal break-in stuff. I hear people running these motors down to 1600 with a reliable idle.

Or maybe one answer will answer both of my questions. hmmm

If someone told you he was getting repeatable and consistant idle at 1,600 he must be turning the engine with an electric motor, I get the best and most reliable and repeatable idle speed at about 2,300 on all my Saitos. I'm not trying to be a smart alec but the lack of responses to your question speaks volumns. As to the first question I think the low end is rich, you might try leaning it some and closing the throttle barrel a little farther, this should get you on track.

that's just what I'm seeing after searching the subject on here. Thanks though I'm going to try to lean it out a little more.

heres what one guy said

Mike: You have a great engine. I have two of them, and have learned that the tank placement is critical. The tanks in mine were both low, in relation to the carb, and would run fine @ low end, and mid-range, but would die when I advanced the throttle. I re-located the tanks to approx. 1/8 inch above the carb center, and both engines ran well. Also they require considerable break in time. After this, both engines run at about 10,500 w/a 13X6 prop, and idle at about 1800 rpm. Be patient w/your engine and you will be rewarded w/a long service life.

Good luck, Bill

how do you get a 1600 idle. mine with a 12x8 is really good at 3000 and is reliable to 2800 thats it with 15% coolpower

Well I"m glad that that's all your getting, that means I'm in a good range and can stop fiddling with it to try to get it lower. Thanks again

Joey,
any chance we'll get to see this puppy before the snow flies?

Hallo!
It is my experience from 27 years of R/C flying that if an engines behave as you discribe itīs too lean......
But to be sure ...how does ist behave when you advance the throttle...?? does it sputter and hesitate...before it rews up ?? Then itīs too rich!
On the other hand if it just hesitates for a 10th of a second before it rews up or if it just dies when you give full throttle itīs set too lean and you have to open up the idle needle, (counter clockwise).
When discussing idle rpm, 2000-2300rpm is a good idle on any two or fourstroke engine. Any lower and it gets hard to maintain a safe idle.

Some adwise:
The carb opening should be around 1-2mm open at idle!
Fuel: 5-15% nitro
Oil: 15% Syntetic, Motul "Micro", Graupner Aerosynt 2 or Aerosave. ( this is what we use in Europe on all engines, Castor is a thing of the past).Motul oil could be bought in motorcycle shops as the French Motul company specializes in making oil for motorcycle racing.
Glowplug: OS F
Fueltank: For a Saito .72 a 200cc-240cc (8oz)is enough.The tank center should be in line with the carb fuelinlet orrifice when the airplane is horizontal.Tank as close to the engine as possible
Propeller: APC 12x7,12x8 13x6, 14x4

Try it and see for yourself!
Good luck!
Jan K
Sweden

I've ordered a 12 ounce tank that will fit just because, I really don't know if i'm going to install it though, alot of work you know. It hesitates for a tenth of a second so I'm going to check to see if it's too lean, vince, I'm flying this saturday early, I'm going to send out an email later just in case you haven't read this by saturday, I can't wait. I'm glad I've found this forum, saves you guys about 100 questions being asked from me.

Thanks everyone

Ok, I read it. Company coming this weekend, but I plan to be there.

shane get his **** together yet with that stick