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Saito 125 question

Old 11-28-2009, 07:23 AM
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gauravag
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Default Saito 125 question

Hi all,
A couple of months back, I purchased my first Saito - A FA-125 . I have it mounted on my .90 size Javellin, a patternship.
I did the break-in as per the instructions, and have around 3 gallons of fuel through it. Idle mixture has also been set, and valve clearences checked as per the manual ( no need for adjustment found though ) .
My fuel is 18% lubricant which is a blend of castor and Klotz KL 200. I use no nitro, as its not available in my city.
The prop i use is a Zinger 16x6 wooden prop.
The problem i seem to face is, that firstly the max RPM i get is 8200. If i try to lean the HSN beyond this the RPM drops. So on ground, i richen the mixture a bit and keep the max RPM at around 8000.
The needle is very very sensitive. I mean just one click makes a difference of 200 rpm. Is this normal ?
Then in flight, i note that when the plane is inverted, the engine revvs up, and seems to run more smoothly, and i get more power than upright... Could it be the tank position ? the tank is just behind the engine, and the carb is slightly above the centerline of the tank ( 1/2 inch or so ) .

I heard this was a very good engine, but somehow i cannot seem to get enough power out of it. I think it has something to with the setup, because the engine runs better when the plane is inverted or on knife edge.

Please help me out with this.
Thanks
Gaurav
Old 11-28-2009, 08:32 AM
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Hobbsy
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Default RE: Saito 125 question

Gaurav, try setting it 200 rpm rich with the tank half full, it will be a little rich on take off but run fine after the climb out. A narrow needle setting is normal for low or no nitro.
Old 11-28-2009, 10:37 AM
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daveopam
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Default RE: Saito 125 question

With no nitro, I would use a smaller prop. There are some 16x6 props that my 1.25 wont turn and I use 15% nitro. Try a 15x6 or 15x7. BTW I get 9,800 out of mine on 15% with a 16x6 MA Scimitar.

David
Old 11-28-2009, 11:02 AM
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w8ye
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Default RE: Saito 125 question

With no nitro use a 15 X 6 prop

With no nitro, the needle will be extremely sensitive

2% Acetone in your fuel may make the needle a little more manageable. Try a small batch of fuel and see how it runs.

Saito glow engines like nitro with many of the USA people in this forum running 30% nitro and others running 20% nitro
Old 11-30-2009, 01:11 AM
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gauravag
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Default RE: Saito 125 question

Thanks,
I used a 15x6 prop and got 9200 max RPM , and tuned the HSN at 9000.
I hope i wouldnt have damaged my engine by running it at peak RPM with the 16x6 i was using.
The compression is good, and starting is easy. What would be the probable signs of damage, if any ?
Thanks !
Old 11-30-2009, 01:31 AM
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Default RE: Saito 125 question

I don't think you damaged your engine as long as you had the needlle set correctly.

The engine seems to perform well in the 8000 up to 9000 rpm. Try to prop it in this range

The true measure is flying the plane and try different props and decide what you like the best
Old 11-30-2009, 01:40 AM
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gauravag
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Default RE: Saito 125 question

Exactly. When i used the 15x6 prop and got around 9000 RPM, flying was just the way i wanted . When it eas earlier at 8000, the airplane was sluggish and that 1K made the difference i was after. Plus i think i am running it now 200 RPM lower than the max i can get, so it would be good for the engine.
Will use your Acetone tip too to see if it makes the needle more manageble. Right now Just 1 click can change 500 RPM ! I never so such a sensitive needle !

Thanks
Gaurav
Old 11-30-2009, 08:34 AM
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Default RE: Saito 125 question

I think Saito engines were set up to use nitro as their biggest market is the USA.

But to not run nitro the needle gets very sensitive. The get around this, people that can get the nitro use 5% and the others use a little acetone.

The smaller prop helps with needle spread compared with the big prop
Old 12-01-2009, 08:11 AM
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Default RE: Saito 125 question



ORIGINAL: w8ye

I think Saito engines were set up to use nitro as their biggest market is the USA.

But to not run nitro the needle gets very sensitive. The get around this, people that can get the nitro use 5% and the others use a little acetone.

The smaller prop helps with needle spread compared with the big prop
One day i will try this same engine with 15% nitro fuel and that would prove it all. So far i have always used OS engines, and though they were heavy (compared to Saitos ) , they gave more power on no-nitro fuel, and in general performed much better ( no nitro ) .

Thanks again for the assistance. BTW Acetone would have no negative effects on engine longevity ? I got a 500ml bottle today and will try it on my next batch.
-GA
Old 12-01-2009, 09:28 AM
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Default RE: Saito 125 question

The acetone will not harm your engine

At levels mucher higher than 5% and the fuel will not run as well
Old 01-25-2010, 03:39 AM
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Default RE: Saito 125 question

I have run as high as 45% on my saito 125 no problems. i do have a problem now though. In my last crash i had to replace the carb high speed needle and spray bar. i cant get it to richen up now. i have the spray bar in the factory position. anyone have any problem like this. I am about to order a new carb for it. i have tried three different fuel tanks and same thing. i might try a pump on it to see if it helps tomorrow. Oh yeah on 45% it turns a apc 13x11 at 11,400-11,600 on the ground.
Old 01-25-2010, 07:53 AM
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Default RE: Saito 125 question

If it won't richen up, that means the LS neeedle is too lean, this will render the HS needle ineffective.
Old 01-25-2010, 08:41 AM
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Default RE: Saito 125 question

Hi gaurav i always nearly double the two stroke engine size,run 10%.
Old 01-25-2010, 09:06 PM
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Default RE: Saito 125 question


ORIGINAL: gauravag

I did the break-in as per the instructions, and have around 3 gallons of fuel through it. Idle mixture has also been set, and valve clearences checked as per the manual ( no need for adjustment found though ) .
I think it is unusual that your valves didn't need ANY adjustment after 3 gallons of fuel. My Saito 1.25's valve clearance changed about 0.001" (~0.025 mm) while breaking in! After break-in, valve clearances do not change nearly as much, but they still do wear a little. I try to check mine about once per year, but more often when they are new.

I recommend you check your valve clearance again with a good set of feeler guages. The one Saito includes with the engine is too thick (0.004" or 0.100 mm). The thickness of the Saito guage is the same as the maximum valve clearance they list in the manual. That makes it pretty useless to set valve clearances with, in my opinion.

I prefer to set my valve clearances at 0.002" (0.05 mm) or even less.
Old 01-26-2010, 08:59 AM
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Default RE: Saito 125 question

The tool that Saito supplies isn't a feeler gauge. You can't feel the fit with it like a good set of feeler gauges. Not picking at what you said, Ken.
Old 01-26-2010, 10:45 AM
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Default RE: Saito 125 question

I acquired one of these in a engine trade about 10 years ago and I've used it ever since on all my four strokes. I have Saito wrenches in the little box also. .
<pre> .04mm Feeler Gauge (.0015 in) .10mm Feeler Gauge (.004 in)</pre>
$10 http://www3.towerhobbies.com/cgi-bin...&I=LXCN31&P=ML




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