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Saito 65 Prop Size Question

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Old 04-18-2008, 07:29 AM
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roryschmidt
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Default Saito 65 Prop Size Question

I bought a used cub (simular to a Goldberg aniversery Cub). It has a used Saito 65. I read the Saito website and it recommends a 13X6 prop. I tried it and can't get the plane to climb. I tried a 11x6 and the results are even worse. It floats along about 20ft off the ground. With the 13x6 I got it approx 40 ft off the ground. When I try and climb it stalls.
I have checked the RPM of the motor and it runs full throttle at 8200rpm consistantly. I would have expected to be able to gain altitude at 1/2 that rpm.

Any thoughts would be appreciated. The airplane and motor came from an older gentleman who has flown this plane a lot. Could it be the motor is just wore out ??
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Old 04-18-2008, 08:15 AM
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Nathan King
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Default RE: Saito 65 Prop Size Question

You should be getting MUCH more than 8200 from an 11x6. In fact, an 11x6 is so small (too small) that you should be over revving the engine. I'm getting mid 9000's with a 12x8. Remove the rocker cover and check valve clearances with a thickness gauge. I set mine to three thousandths of an inch. Since you are flying a Cub use a large diameter prop with a smaller pitch while keeping the prop load consistent. I had a 65 on a 81" wingspan cub, and it pulled that thing around well at half throttle.
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Old 04-18-2008, 09:45 AM
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Default RE: Saito 65 Prop Size Question

As Nathan said, check the valve clearance. You should be turning about 10,500 - 11,000 with a 13x6 prop. My Saito 72 will turn 11,000 - 11,300 with a 13x6 prop (I have it adjusted for 10,800 so as not to over rev the engine)
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Old 04-18-2008, 09:55 AM
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Default RE: Saito 65 Prop Size Question

Hi!
13x6 APC is the prop to use if in a sport airplane or warbird like the Kyosho
Kawasaki Hein.
A 14x4W APC could perhaps be used in a slow flying model .

The fuel you should use is 10-15% nitro and the glow plug OS F!
Tank should be 8oz-10oz (240-300cc).
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Old 04-18-2008, 06:14 PM
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Default RE: Saito 65 Prop Size Question

I've used a 14-6 MA on my .65 since I got it. It will turn about 9000 rpm, right at the torque peak. No need to rev a 4-stroke to redline.
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Old 04-21-2008, 08:03 AM
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roryschmidt
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Default RE: Saito 65 Prop Size Question

Thanks for the feedback. I did set the valves this weekend. They we out by perhaps a thou. I have another cub with a Saito 65 and it works fantastic. I can take off at 1/2 throttle with a 13x6.
Has anyone ever had one rebuilt at the factory?
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Old 04-21-2008, 01:37 PM
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Default RE: Saito 65 Prop Size Question


ORIGINAL: roryschmidt

Thanks for the feedback. I did set the valves this weekend. They we out by perhaps a thou. I have another cub with a Saito 65 and it works fantastic. I can take off at 1/2 throttle with a 13x6.
Has anyone ever had one rebuilt at the factory?
Yes, you should be able to get off at half throttle. That's what I always did with my 1/5 cub - it was nice and gentle, very scale looking.
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Old 05-01-2008, 02:33 PM
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Default RE: Saito 65 Prop Size Question

I got a 65 in my 40 size aeronca champ with a 12-6, its probly in the 9500. I can take off at half throttle and scale flight is at about a 1/4 and with the show struts off it'll pylon race with the best of them. Im no expert but I'd think valves could be out of adjustment or there could my fuel restriction somewere in the carb, fuel lines or the tank.
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