I started to break in a new Saito 56 yesterday. This is the first four stroke that I have owned so I was a little apprehensive aout what to expect.

I followed the manufacturers instructions and fitted an 11x7 APC prop and opened the high speed needle 4 full turns. The engine started by hand after about twenty flicks with a chicken stick (quite an exciting back flick on occasion).

Two questions : when using a chicken stick do you rotate the prop until after the compression or just before the compression before giving it a flick?

2nd question : The instuctions indicate that after running one tank full at half throttle and then one and a half tanks at full throttle then to lean the engine out until in runs at 9000-9500rpm for another half a tank. No problem so far. Continuing with the break in (on a test stand by the way) and cycling the engine between high and low throttle for another half a tank, the instructions indicate that if the engine runs smoothly at full throttle by this stage then ground break-in is complete. Well my engine was definitely running smoothly by this stage and the needle valve had only been closed maybe a 1/4 turn so still very rich - lots of smoke (cough cough).

So the question : with the 11x7 prop on, leaning the needle valve will cause the engine to run in excess of the 11000rpm ground speed maximum quoted in the manual, and is still very rich. would a 12x6 prop be a better prop selection for breaking in the engine in the air?

I have not tried to set the low speed needle at all as yet, but the engine transitioned smoothly on the test bed from low speed to high speed.

I had an OS 52 Surpass four stroke a few years ago. For the first start to begin break-in, I used an electric starter, and it started pretty much right away. I didn't use a chicken stick so I can't answer that part of your question.

However, if I recall, I never allowed it to get over 10,000 RPM. In fact, it was more like 8500 or so. It pulled pretty good at that RPM so I was satisfied with the performance.

I don't know about anyone else, but I would be a tad bit leary about going over 10,000 RPM just for the mechanics of the engine. The four stroke has many more parts than a two stroke engine, and that's more parts to move in coordination. And at that RPM, well, I just feel that it is skirting disaster when going above that.

The best way to control that is with a prop, and with the pitch of the prop being the major factor here. And, of course, making sure you are not running to lean, which will be a bigger detrement to that engine than RPM would be, and of course, the combination of over-heating by lean mixture, added with the 'excessive' RPM, may prove to be to much.

Most people that I know do go higher in pitch with their four strokes because of the torque that these little jewels produce. They can turn a prop with a higher pitch than their two-stroke counterparts. But, the power output is usually lower than their equal size two strokes.

Now with that said, what I would do is go ahead and make sure it's not to lean (and it sounds like it is not.. but just make sure..) and then increase the pitch of the prop until you are satisfied with the performance.

Oh.. is this engine on a plane? Or did I overlook that part of your post? If it is, then fly it. See how it performs with various props. You may be pleasantly surprized at what the performance is with different props than the 'break-in' prop.

Best of luck.

CGr.

One more little point here..

After re-reading your post, there is one point that I missed and perhaps you don't quite understand. Lowering the pitch will increase the RPM. You are already at 11,000 with the 11-7 prop. I would not go any lower in pitch.. in fact, I would go higher in pitch to get the RPM a tad lowere, perhaps below 10,000. I tried to point that out in my previous post, but wanted to make that clear that I believe that is to high of an RPM range for any four stroke engine.

CGr.

First of all, how do you know that the engine is exceding 11000rpm. To set up any 4stroker you will need a TACHO. Second check out [link=http://saito-engines.info/throttle_setup.html]HERE[/link] to runin and setup up Satio engines, lots of questions answered and a lot of info.

Cheers

Yes I was using a tacho.

Will the rpm increase even if the prop diameter increases with a drop in pitch.

I would rather have a lower pitched prop that will slow down for landing (4 star 40) than a higher pitched prop to wizz around the sky.

I was thinking of a 12x6 prop, which I have currently installed in the plane or a 13x5 or 13x6.

Andrew,
No, when you increase the diameter, the RPM's will go down, even if you decrease pitch by 2 inches. In fact, I own this exact engine and I run a MAS scimitar 12X6 on it and it is a perfect combination. You will love this engine. One of the smoothest running engines produced....
After a gallon or two, lean up the low end a tad (all saitos are rich on the low end) and it will start sipping fuel, at around .5 oz/min....

I think you might like the results you get with a Master Airscrew 12x6 K-Series prop. The K series props are designed for four stroke engines in particular, and feature a wide blade. They provide a terrific amount of thrust and ideal load for high torque engines.

Breaking in your engine according to the recommendations in the owner's manual is always the right thing to do. It sounds like you've been patient and followed all of the right steps to assure smooth performance and long life from your Saito .56 four stroke. Congratulations and enjoy!

By reading the Saito specs posted by The Ghost you will note that this particular engine is intended to run with a prop range from 11 x 8 to 12 x 8 so definitively you are running with a lower end prop.
Many engines run different but your goal, as has been mentioned is to have a peak near 9,500 rpm. so you will need to find the right prop that will give this numbers (best torque of the engine).
I would try a 12 x 7 which is with in the range and is not much bigger than the one that you are using already.
Also keep in mind that many 4 stroke companies will suggest to break in a new engine with a lower end prop. just like you did, but as you are reaching the higher RPM numbers that the engine is able to give, you will want to select another prop. to stay in the operating range.

Regards.
Alfred.

Hi,

I have been runing my saito .50,s with a 12x4 and the new saito .56 I just broke in with a 11x7.5 master airscrew and set the needle with a tac. to 10,000 rpm's. The 56 runs great and idles down, well below 2,000 rpm's , eveyone coments at the field how well its running and responds.

One thing , in all the saito's I have had . I set the valves before running, check them half way though breakin and reset the valve clearence after break in. Its real important to have the valve clearence set properly.

Hi!
If you fly at sea-level a 12x6 is the prop of choice for most sport airplanes .
This prop will yeald aprroximately 10000rpm. An APC or RAM is what I would use. MA black with white tips is no good!

Thanks everyone for your comments. I have fitted an APC 12x6 to the engine and mounted it in the airframe to get all set up for the maiden - hopefully this weekend - weather permitting.

As far as the chicken stick goes - well I bought an electric starter until I can work that one out

I will adjust the HS needle at the field for a max rpm of <9500.

Once warm, saito's will usually start by quickly flipping the prop backwards. Grab it by the spinner (if you have one) and flip it quickly BACKWARDS. Once it hits compression, it should fire (of course, make sure you have properly primed it first).
I just use an electric starter on all of mine.....

Following on... I have not been able to maiden the plane yet due to high winds for the past 2 weeks or so.

However i have fitted the sengine to the plane with and 12x6 APC prop and thought i would run it in the yard today (2.4 GHz). The engine fired up immediately (less than 1sec on the starter). After 30seconds or so to allow the engine to warm up I remved the glow starter - the rpm dropped which if i understand correctly means that the low speed needle is too rich. I kept the engine running by increasing the rpm a little and then went to WOT and tach'ed the engine at around 9300rpm but while holding the tach the rpm started dropping to 8300rpm and then slowly cycled a little without me moving the needle. The engine would transition without spluttering although the transition was slow. The engine ran reliably and did not cut out at all for the full tank of fuel as I "ground handled" around the yard.

But the gradual fall in rpm happened a couple of other times. I leaned the HS needle a couple of clicks until the engine seemed to be running at a constant speed of 9500rpm and then shut off the engine. It seems to be ready to fly but I am a bit concerned about the variability in rpm at WOT. Is this just a function of breaking in the motor or should I make the adjustments to the low speed needle and check it again?

This sounds little air bubbles in the line...I have the saito 65 with a 13x6 prop and it is scary powerful!!!..Ifly mostly .049 to .15 stuff ,,I bought the stick/saito from a bud and it started on a back bump the first time at full throttle and scared the crap outa me, not near as fun as my little stuff though, may sell it myself...Rog

I should have meantioned perhaps that the fuel tank is set up with three lines using a fuel dot. Everything seems to be tight though no obvious air leaks.

Is this something that will settle down after everything is bedded in?

I use a chicken stick on my 82a. I set the prop up where the
Compresion stroke is at 2:30 when looking at it from the front.
I start mine clock wise because i'm right handed. This seems to
works great for me. I'm running a 13x6 mas K series or a TF 13x6
power point Wood prop. Mine has just over a Gallon run through it
so far and has not been over 9200 rpm's on the ground. Not sure
what rpm's I get in the air, when the prop unloads. Maybe around
9400-9500 rpm's

Bob

Saito's will be rich on the low end from the factory. Leave it that way for a while. A lot of your flying is done on the low speed needle (1/2 throttle or less), so having this rich helps. Also, at idle, there isn't much air flowing over the head to cool the engine, so more oil and fuel helps keep it cool. Idling is the roughest time on any air cooled engine.
It also sounds like you might be a bit lean on the top end. That usually causes variations in the rpm's at WOT. Try opening it up, to about 300 RPM's below peak. If it still runs erratically, then you may have an airleak somewhere.
After you have a gallon through it, then start leaning up the low end to get it like you want it.