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

Pawel,

It appears your alternate fuel is not good. (At least this particular container) Go back to your Polish fuel for now.

Saito's are not more picky about their fuel than what the Magnum is.

Of course i've already ordered new container of my favourite fuel But i was curious how you guys exactly adjust LSN. I do it like this and till now it worked great: 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.
But here it doesnt work right

After you get the low speed mixture leaned out and peaked, you have to richen the idle mixture back up to where the engine can go to high speed without quiting.

It goes up without qiuting now i went up without quiting before when was leaned. Only issue is reving up from middle revs. In my first post i described it. It seems to lean out when the throttle is opened about 1/3. And during idle it loads up with fuel. Any ideas?

w8ye, will you help me? As saito club member you should know everything ;D

There are combinations that can cause the mixture to be not ideal at different throttle settings

One is tank height. Too high and you will have a rich midrange. Too low and your mid range can be lean.

The ideal tank height is even with the needle valve for an aerobatic plane.

A too large propeller will cause a rich mid range and likewise, too small of a propeller will cause a lean mid range.

The ideal propeller for the Saito 91 is a 14-6.

The prop is 15x4 wooden and light, tank in line with the carburateur. But in fact, this leaning in middle revs becomes during the end of flight- when theres a little fuel in my tank. I must think about a Perry pump. What kind do you suggest- oscilating or underpressure one?

A 350 cc tank would be about the right size for this engine. Do you have a larger tank?

The Perry VP 20 is pump that most people are using

http://www2.towerhobbies.com/cgi-bin...&I=LXDG61&P=ML

I like using a check valve in the muffler pressure line and a Cline demand regulator myself.

i have 250 ccm tank. I fly 12 minutes and still have 1/3 of fuel left. But on the other fuel i hav almost 1/2 tank left after 12 minutes of flight. And model was not so much dirty from unburned oil.

Based on your remark that it happens in the late part of the flight as the eng leans due to lower fuel in tank - you probably need to richen both needles just a small amount [a click or two for high needle and maybe 1/16 of a turn on the low needle]. Saito's like to be a little rich.

I lean the bottom end untill the engine starts quitting in low power situations like right after landing or verticle manuvers if you pull the throttle back. This will have the engine running a bit rich at idle when the trank is full but it needs to be a bit rich at idle just like it needs to be a bit rich at full throttle with a full tank to compensate for leaning while flying. Cline regulators work well and allow you run peaked out but I would stay away from Perry pumps unless you like to fiddle. A bit more break in time would not hurt.

I installed VP30 on my plane and must say YEAH Saitos love Perry
Engine works perfect from idle to the max. I have HSN about 1/5 turn more in but i think ill repeak it again bacause it looks a little too rich. Lsn is also more in than it was before. I had a little problem during first flight because I leaned the lsn too much and a dead stick happened during approaching to hover. Happily it was obout 10 meters above the ground.
Although theres more smoke from exhaust model is cleaner a lot than it was before. Strange, isnt it? I dont worry about it of course but am curious why. Also fuel consumption increased, what woories me a little, but i hope it will stabilize when i lean the high end properly.

The engine is running better due to runin (or as we say break in). Saitos seem to run better with age and more hours on them provided they have been properly lubricated. Fuel consumption will go up with a Perry Pump or Cline system as it is being force fed to the carb (albeit at a constant rate). That is why the engine does not tend to go lean at the end of the flight with those systems installed. Those systems are very consistent in operation, less variance and thus slight increase in fuel consumption. I found the Perry Pump made my airplane run a little rich. When I took it off, I leaned out the engine. I really did not need a Perry Pump in my application, it was sort of a trail run to see how it operated. While it ran well, the engine seemed to run better without the Perry Pump, at least it used less fuel.

Cheers,

Chip

In my case the fuel consumption almost doubled, so i think i run a little too rich. But engine has a power like never before. Im surprised how collosal power it has to pull a 3 kg model from hover to fast vertical woow.