MySaito is not strong. Does the timing being off a little effect the rpms? Engine runs fine but only gives about 9100 rpm with a 13 X 8 apc prop... The engine received new bearnings and seem to be find until I put it in a Extra 540, 60 size airplane.... I have checked everything and can find no air leaks and the low end and high end adjustments have been checked and rechecked my many other experienced pilots... How would the timing effect the engine if it were off one tooth?

One tooth is the same as a million. One tooth equals quite a few degrees of timing error. The motor will run like crap.

Make sure the timing is dead-on. There is only one correct setting.

Checking the timing this weekend with the man that installed the bearnings...

richard, Race is right, if your timeing is off just one tooth you wont get close to 9100 rpm with that prop

Then let me ask.... if that is true and I hope it is correct... then the timing must be correctly set if I am getting 9100 rpm with the 13X8 prop?... I will not take the engine off the airplane and I will just keep trying to find the problem.... Would you recommend me going to a 14 X 4 or a 13 X 5 prop for more rpms?

In my continuing search for the lack of rpm/power in my Saito 91 I took the main needle out and was blowing air through all of the lines both at the carburator and the muffler... I noticed that the needle was not sharp on the end... sort of blunt... I pulled a needle valve out of my Saito 100 and they appeared to be the same exact needle except the needle in the 91 was about 1/64 inch or less shorter... and not a sharp point... It was blunt! Tomorrow I will test run this engine again but this time with the needle from the Saito 100... Hopefully I have found the problem... What do you think? Thanks... Richard

Hi Richard: I run a 15x4 WIDE APC on my Satio 91 for 3D on a MOJO 60
What Extra are you flying and what does it weigh? What fuel and nitro % and most important you only talk about ground RPM, how does the engine prop combo fly? For full on 3D you want the biggest dia lowest pitch prop the engine will happly turn.
For lots of Satio info go to the glow engine form and search for "club satio" Post your question there.
I have not checked my RPM will be out Sunday I can check and post for you.
Eric

I think that you have the engine over propped where the engine doesn’t have enough power to turn the prop and the RPM's that you want it to.
I noticed that your pitch was very high try going with a 14x4 or a 13x6 or something like that any thing to get pitch down. If the prop
does not give the required thrust then try a wide prop. I think that your motor is fine it just is over propped so just to make sure try a different propeller.

Flyer 202


Specs for Saito .91

Type: 4-stroke
Displacement: .91 cu in (15.0 cc)
Bore: 1.11 in (28.20 mm)
Stroke: 0.94 in (24.00 mm)
Cylinders: Single - Chrome Plated
Engine (Only) Weight: 19.6 oz
Crankshaft Threads: M7 x 1mm
Benchmark Prop: 14 x 6 Zinger @ 9,100
Prop Range: 12x8 - 15x6
RPM Range: 2,000 - 11,000
Fuel: 10% - 30% Synthetic
Mounting Dimensions: 116 x 60 x 117 mm
Muffler Type: Cast
Cylinder Type: AAC
Carb Type: Barrel, 2 Needle Valve
Crank Type: Ball Bearing

I have an O.S. 91 Surpass and I get about 9600 rpm with a 13x8 at a slightly rich setting.

Just my 2 cents.

I will test props today & new needle

Will not loop

Hi Richard; I see from your previous posts this is a used engine, pull the cylinder jug and check the piston and liner for scoring and the piston top for carbon build up. and again how heavy is the plane?

8 1/2 pounds

I adjusted my Saito 91 a couple weeks ago - using an apc 15x4 it peaked at 9700 - set it at 9400 for flying. That is using 15% fuel. I believe that 13x8, 14x6 and 15x4 provide about the same load on the engine.

The "One tooth is the same as a million" is not correct. Try 180 degrees off, for example, and you will see what I mean. The engine won't start, let alone run. With one tooth off, the engine will still run, just not as good as it should.

"Make sure the timing is dead-on" is excellent advice for this discussion.

"There is only one correct setting" is not all together correct, considering what effect cam timing can have on an engine.
But, in this instance, and without a way to slightly alter cam timing, I would stick with the factory setting.

Also worth noting, this is a used engine, and as such would have some wear in the cam gears. How much is the question.
A lot of wear could cause the cam timing to be a bit retarded. Enough to cause running problems. That's why people replace timing belts and timing chains in their vehicles.

I don't know how much effect a tooth off makes to a Saito.
BUT, I know, from personal experience, on a Chevy V8 engines, which are a 4 stroke engine, just bigger, that with the timing retarded one tooth, the engine will still run, just not strong. Nor will it rev quite as high as when the timing is set right, or slightly advanced.

With the one tooth retarded cam timing, on the Chevy V8 engines, not only would the engine not rev as high, but also rev slower, and the engine will run hotter also, which can kill your engine.

I would say tear it down and make sure. It's not that big a job, and then you won't have to worry about "is it right, or not".
The peace of mind is worth more than the little time it would take to tear it down and make sure. At least to me.

Of course, "tearing it down to check it out" is just my opinion too, of what needs to be done.


Note: If you have no experience with tearing down engines and repairing them, then get some help from a friend that does and learn how at the same time. They are worth learning about.

There is also some good reading about Saito engines here;
[link=http://www.rcuniverse.com/forum/m_5843055/tm.htm]The Complete Saito Notes by Bill Robison[/link]
And here's the Saiyo manual;
[link=http://www.horizonhobby.com/ProdInfo/Files/SAITO_Small-Medium_single_cylinder_Manual.pdf]Saito Small-Medium Single Cylinder 4-Stroke Engine manual[/link]

Good Luck!! I hope you get it figured out.[sm=thumbup.gif]

If you can get this thread moved to the Glow Engine forum, you may get some answers from others that have had this problem.
Just a thought.

Have the valve clearances been checked - that can reduce power and rpm.

Hi Richard; The engine and prop you have should fly a 8.5 pound plane with power to spare The 13x8 is not too much load I flew a Saito 82 with a 13x8 on a Lanier TR260 that came in @ 9 pounds and had lots of power.
We are dealing with a used engine with replaced bearings, Why?
Were the bearings replaced with the right type and were they seated properly?
If the old ones were rusty and the engine was ran the cylinder lining is damaged.
Send the engine in for service. Horizon has a great service department and do not over charge.
They will strip down the engine and call you before they replace parts.
And one tooth on a Saito has a major effect. (done that)

Youngun...

Since you state that you don't know how a timing error will effect a model 4C (but proceed to correct my error using a Chevy V8 as your reference).....

I suggest you discover for yourself how poorly a model 4C actually DOES run with the timing one tooth off, and get back to us.

Until then....I'm not wrong.

You will know right away if the timing is off by one tooth just by the sound. It is Very obvious and sounds pretty sick and way less rpm's. It took me a few tires to get my tooth lined up when I put it back together. Everytime I lowered the gear down it would turn just enough to where it was not right. After a few tires I got it.

Thanks to all for your help