Saito FA91 adjustments- help needed!!!
 

Hello!!!

I have my Saito for about month. It has about 4-5 liters thru it. I initially broken it in on fuel with 10% nitro and 19% oil synth/castor mixed. It was polish fuel, so i decided to buy something with more reputation and i went with Model Tchnics Formula Irvine 10% nitro/ 18% synth/castor. I remembered i liked this polish fuel more when i had Magnum 4-strokes but i hoped Saito will like more expensive fuel. It appeares it doesnt.
To make this engine work well from idle to full throttle i must have low speed needle very rich. If i set lsn for perfect idle i get very poor and lean middle range. Still on the ground whet i open the throttle about 1/3 and keep it reving it emits no smoke, sound becomes very soft, and when i rapidly give full throttle the engine doesnt spin up smooth. It chokes for a split second. It looks like much too lean. But when idling for about 15 seconds it smokes a lot when i open the throttle. Of course with such rich lsn setting the idle is not as smooth as it was with leaner setting. But i prefer this instead of destroying my engine by overheating it.
High speed is set with tahometer about 250 turns/min lover than max.
I write all this beacuse of the rich setting my Saito burns a lot of fuel and what worries me most my model is more dirty after 2 flights than it was before after all day flying.

What do you think- is this the fuel, or maybe i adjust something wrong? I'd be grateful if someone described how he adjusts lsn in his FA91.

Thanks

Pawel

RE: Saito FA91 adjustments- help needed!!!
 

pawel,
I cannot say much for the fuel. It may be possible that the fuel could be old and going bad on you. I have a lot of experience with four strokes. You always set the high end first. Run the engine untill you get peak rpm and turn it back ( richen) about two clicks. Four strokes and saitos in particular like to run rich. Any time you change the high needle it always changes the idle setting so thats why you do the high side first. You then will tune the bottom end ( and it needs to be slightly rich also) untill the engine will idle all the way down to a slow idle. Look for smoke, it should smoke a little. If when you open the throttle the engine does not accelerate smoothly and quickly, you must determine if it is rich or lean. If you have smoke at idle, it is rich. You would then slightly turn the low side untill you get a smooth transition.

If you do this and the engine won't run right, you have bad fuel. on another note. My experience with four strokes is that they will run better, idle smoother and be less finicky on 15% to 20% nitro. I don't run any 10% anymore. We fly alot of 3d and don't need the engine to die in a harrier 1 foot off the ground.

Good luck.

RE: Saito FA91 adjustments- help needed!!!
 

Thanks for ur answer. I do like you said- first high speed and a little richen up, then low speed. But like i said- i must set the low speed needle very rich otherwise i have too lean middle speed. It makes the idle very sharp and lots of smoke and oil on my model.
I know that 10% nitro is marginal for Saito but on the first fuel it ran very happy. Now it is very unhappy :) I didnt mention that before but right after the initial break in on polish fuel i got 10500 rpm's with my 15x4 prop, and using the Model Technics fuel i get only 9900 rpm's.

I used to set the low speed neddle like this: screw it in in 1/8 turn steps and if engine accelerated i clicked my throttle trimer down. Then again lsn turned in and again throttle down. Untill the piont where turning in caused motor to drop down rpms's or just died. And from this point i just turned lsn about 1/4 turn off. All engines ran great, had reliable idle and great transition.
With this engine it just doesnt work.

Jugflier tell me if you do it my way or Saito's will not work this way?

RE: Saito FA91 adjustments- help needed!!!
 

Pawel, I would try a differnt brand of fuel if available. If the engine runs good then you got a bad batch of fuel. I know that Satos have to run alittle rich and yes they gook up your plane. If no other fuel available i would go back to polish fuel.

Hope this helps,
Curtis

RE: Saito FA91 adjustments- help needed!!!
 

It also seems that Castor oil blends smoke more and get stickier than synthetic fuel.If I was you I'd get the best 20% nitro synthetic fuel you can find.
Another idea would be to very carefully check your valves for proper lift and seal after the break in period.

RE: Saito FA91 adjustments- help needed!!!
 

I agree that castor fuels smoke more and leave model more dirty but polish fuel has more oil in it (19%) and more castor and Model Technics has only 18% oil and less castro in it(only 20% of oil is castor, the rest is synth) And more smoke and dirt stays after flying on this less oiled and less casrtoled fuel. Strange, isnt it?