Need help with Saito 125
 

I bought a 125 and put in a CG Ultimate after blowing up an O.S 120 pumper due to a ceased fuel regulator. I broke it in rich using 15% nitro and 18% syn oil. after leaning it out abit i throttle it up slowly it almost sounds like it backfires and quits after 3/4 throttle. the needle is set 4 turns out but there its not behaving like its too rich, throttle response excellent and no smoke any suguestions? After that I pulled the plug to check its color and I gulled the top of the threads in the head and i was thinking about chasing them with a tap, what is the thread size for the glow plug?

thanks for reading

Get 'em up and down is one peice

RE: Need help with Saito 125
 

I only own OS & Magnum four strokes. They don't blow a lot of smoke when they're running well.
Every Saito I have ever seen blows a ton of smoke. Maybe all of the owners deliberately run them too rich??? I have no idea, but, backfiring usually indicates a lean condition.

The glow plug thread is 1/4-32

RE: Need help with Saito 125
 

Thanks, Ive only leaned the low end to get it to idle, I'll try 5 turns out i guess. thanks again

RE: Need help with Saito 125
 

I broke one in for A friend and I have never seen an engine that ran that rich for break in. It took about 6 tanks of fuel before it started to respond to the needles. Before that I was just chasing them for no good reason. After the 6 tanks it started to come in quite well and I got it running pretty well. Took the plane out to the field and flew the plane all day without any dead sticks and it's really A power house, minor adjustments finally got it to that sweet spot.
Yours sounds like it's lean and maybe it could use some more break in time?

RE: Need help with Saito 125
 

This motor ran like a top right out of the box, I thought saito had the settings big time rich but on the high end it was barely smoking at all, ive always set my motors up by peaking them and then richening 400 rpm. I ran 6 tanks through it before i touched the needles, maybe she does need more time. Im now a saito fan even with this problem, do you run a pressure fitting on the muffler to the tank?

RE: Need help with Saito 125
 

I have this same engine.........and without going out to the garage and checking(and I dont want to mess with my settings :),I'd say your 4 turns out is still WAY too far out causing your engine to run like crap. Sure it will run great at idle up to maybe 1/2 throttle,but that is only because its still running off its slow jets. Once your throttle get over about half way,your main(needle) jet will take over and that is where your problem is. I'd guess my needle is 2 and a half turns out,but not sure.

Start your motor and get it to where you can open the throttle wide open and turn your needle in until your motor dies. This will mean you've leaned it as far as it can go causing it to starve itself of fuel. Just make sure you've broken your motor in good first and dont take forever to perform this task. After it quits,turn out your needle a bit and go from there. And USE A TACHOMETER to tune your saito if possible....it helps.

Once you get it close do this.......Start your motor,get it warmed up good......let it idle,then slam the throttle wide open and listen to it closely for the next few seconds. If it revs up real high upon opening up the throttle,then slows down a bit after about 3-5 seconds......its running rich,and trying to overload itself with fuel. If it revs up high and stays right there forever.....its either right on or lean. And you'll need that Tachometer to tell if its too lean as it will show you your not getting enough RPM's out of your saito. And this is because your needle is not out far enough to give it enough fuel to run high enough rpms. If you get too lean,it will not only not be good for your motor......it might deadstick alot on you during certain manuevers.


Took me awhile and alot of playing to figure all this out..........but keep it in mind and it may help you. And mine still smokes good. Maybe you have it so rich,your not getting enough heat from the motor to burn the oil good and its just spitting it all out.


Oh.....and I doubt you should have touched that low end adjustment. I've never touched my out of the box and idles good and is the best transferring engine I've ever seen.

RE: Need help with Saito 125
 

If your 4-5 turns open then you should be way rich. Try the simple stuff first. Sounds like you could have some foreign material plugging up the HS needle passage causing it to restrict the fuel flow causing a lean condition. Clean it out and try running it again. Mine runs about 2-2 1/2 turns open.
Here's a web sight that you mght find useful http://saito-engines.info/
Fred

RE: Need help with Saito 125
 

Thanks for the info, Ill try cleaning out the high speed needle

RE: Need help with Saito 125
 

In post #5 you ask if you should use a pressure line to the tank - of course you should and if your not the engine could be lean even at 4 or turns out.

RE: Need help with Saito 125
 

Hi!
Never ever set the low speed needle before you have set the high speed needle!!!

RE: Need help with Saito 125
 

My bet is an over lean Lo speed setting richen it up.

RE: Need help with Saito 125
 

I just bought a Saito 125 and did the break-in per the manual. No where in the instructions did it say mess with the low idle mixture early on. I'd put it back where it was. That is flush with the throttle control arm. By the way, mine cranked the first try at the five turn open on the high speed needle and at each progressive leaner setting during the breakin. It has always started on the first turn and runs well.

Also, during the breakin and now, I've added Benol(caster oil) to bring my Cool Power 17% sysnthetic up to the 20% total recommended by the Saito.