VF84sluggo

My Feedback: (55)

Yeah, the two-strokes do pack a lot of bang for the buck, so to speak. Heck, just look at Moto GP racing when they went from 2 to 4 stroke. The cc's almost doubled for the same punch.

But, I don't own any 2-strokes anymore, and have just gotten used to working with 4-strokes. My 100 is soooooo well-mannered, I'm spoiled I suppose. Feel like a 2-stroke is a step back. Now if I was flying 3D, whole new ballgame. But I fly my scale planes scale. That said, I don't want a dog, either.

RC

w8ye

My Feedback: (16)

A OS 120AX is sensitive to fuel draw and keeping the fire going. They quit on you real easy unless the mixture is just right.

Other than that, they are a great engine.

I've been around both the OS 120AX and the Saito 125 at the same time on the same type plane and there just isn't any difference in all out power.

millerhill

My Feedback: (19)

Hi guys, just got a used/new Saito 120s. Never had a Saito before, so I'm looking forward to sparking this baby up.

I'm figuring a 16x8 prop for run in. That sound right? Also, I'm a bit curious about how folks are using the choke plate (or not). looks like a simple push/pull rod through the cowl would work well, but I'd like to hear about how others set this engine up.

It's going in a Goldberg Ultimate 300, so it should cook along nicely. Had an OS .90 in it previously. Just wanted to try out a 4 stroke so I could get more power and less speed.

Steve

w8ye

My Feedback: (16)

Forget the choke plate

The props are a 15 X 8 or a 16 X 6

NM2K

My Feedback: (14)

So OS is still putting carbs that are too large for their engines? I`m not surprised. They started pulling that trick when they brought out their .61F SR back in the late seventies.


Ed Cregger

w8ye

My Feedback: (16)

Other than the too large carb, the OS 120AX is a good engine. The OS 160 two stroke has a carb about the same as a OS 91 FX and it is about as nice of two stroke that size you'll ever see.

Hobbsy

My Feedback: (102)

Ed, you need to modernize your thinkin, he will hardly even notice the change when going from the OS 1.20 to the Saito 1.25 other than the instant throttle and crisper more linear throttle response of the 1.25.

VF84sluggo

My Feedback: (55)

One of the reasons why I'm just not into 2-strokes anymore, airplanes or motorcycles: narrow power band. You get some power, then all of a sudden, lots of it. One of the others is that I don't need the excitement of impromptu dead-stick landings.

charlie1960

Phillip is building himself a torpedo.......lol

NM2K

My Feedback: (14)

Remember when the Saito FA-125 first came out and folks were disappointed to discover that it didn`t produce as much power as the FA-120 that it replaced? Facts are facts and they do not change because of fads or "how it handles". I was referring to top end power.


Ed Cregger

w8ye

My Feedback: (16)

There's no problem with the power developed by the Saito 125. It is as strong or better than the 120S

mike early

It takes a while for the 125 to break in. A long while, in my case.
They say the new design is more powerful, to boot.

blw

My Feedback: (3)

Mine took longer than usual too.

lopflyer- you are member #693

w8ye

My Feedback: (16)

They are usually pretty well broken in after 4 gal

winglift

My Feedback: (10)

I am not sure if this has been asked before, but is it better to run all syn or some castrol in Saito engines (ex Saito 100)?

mike early

Everyone has an opinion on that. If you are new to the Saito line, castor is a good thing for when you run it too lean. In theory, someone that never runs it too lean can get away without using castor, and that would prevent the carbon buildup that I've experienced by using castor. I can tune them pretty well, but I still use castor for insurance.

w8ye

My Feedback: (16)

I like to run fuel that has a little castor oil in the mix

Hobbsy

My Feedback: (102)

Craig, it is important to put the O-ring into the relief in the intake port, then put the intake tube through it, other wise the O-ring will never go into the relief no mtter how much pressure you put on it. You may well have kinked the lower end of your intake tubes trying to force it, hence the lack of pressure against the O-ring.

charlie1960

Whats the difference between the old and new 1.25? How do you tell them apart?

w8ye

My Feedback: (16)

A couple pages back there are pictures.

The combustion chamber shape is different and the valves are at a different angle. The cooling fins are different.

The new cylinder is actually the gas engine FG-20 cylinder head machined to work on the glow engine.

w8ye

My Feedback: (16)

The different 125 cylinders. The "B" version has the parts on it The older 125 cylinder had the threads stripped from the exhaust outlet.
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[img]{akamaiimageforum}/upfiles/22988/Qv54530.jpg[/img]

[img]{akamaiimageforum}/upfiles/22988/At54603.jpg[/img]

charlie1960

would seem i have the earlier model. thanks
i wonder is there any benefit to changing the cylinder.

w8ye

My Feedback: (16)

I think the new cylinder has more power but at $117 a crack, it may not be worthwhile to you?

w8ye

My Feedback: (16)

I've only seen one new style cylinder.

A flying friend brought me a 125A that he had horse traded for from his brother-in-law in Kentucky. He brought me the engine because it had no compression.

I promised to fix it.

The engine had the new style cylinder on it and there was almost no time on the rest of the engine.

The story went that his brother-in-law had crashed the original engine and had broken the exhaust pipe part of the head. So the brother-in-law bought a new head and installed it on the engine where upon it had no compression.

To make the story shorter, the valve seats in the new head had some sort of wax on them and neither valve would seal. I disassembled the head and cleaned the seats.

On Christmas Eve, last year, we ran the engine at the entrance of my garage and I was really surprised how well this brand new head ran with a 16 X 6 prop. It had surprising power.

There's a story about how to go about changing out to a new head on a Saito that has been covered before a few times in this thread but we may have to go over it again some time?

Craig 01

G'day Hobbsy,
Yep o-ring inserted first then inlet pipe,no kink in inlet pipe.It is actually the washer on inlet pipe not fully contacting the o-ring and free to move between o-ring and step on head end of inlet pipe as the whole assembly is sitting further back due to carb mount on the 82B (SAI82B17) spaced further back from original location with the plastic backplate.Removing approxiamately 1.5mm from the carb mount on the 82B back plate corrected the issue as that is the approxiamate difference between the backplates when measured and viewed side by side.