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Max RPM question from the Newbie

Me and my Saito 65 again.... Turning a Master Airscrew 13/6 I can't seem to get max rpm out of it. As I add throttle the engine bogs. Am I at the max throttle for this prop size? ie too much prop? I don't seem to have this problem with say a 11/7. I did a "pinch test" at the highest rpm I could get and it did not rise (it did until I leaned it out a bit more)

According to my book this engine should turn this prop OK, I think the

11" prop was over-reving the thing is why I'm moving to a bigger prop.

Thanks Mark

Reply to
Mark
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On 10/1/2003 3:49 PM Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

What are your RPMs with the 13x6 ? What brand and nitro/oil fuel ? Are you using a tach or doing it by "ear" (You can not accurately tune a 4 stroke by ear) ?

You should have no problems with the prop. Have you checked to make sure your needle valve hasn't picked a piece of lint/crap ? Have you tried a different fuel and/or glo plug (OS F works exceptionally well)? If you are at higher elevations you will need to run higher nitro (20% or better) to get the performance.

Reply to
Ted Campanelli

You can tune a four stroke by ear. Thousands of people do it every day.

Reply to
Paul McIntosh

What RPM are you trying to achieve? You are not going to get over 10K with a 13X6 on that engine. A Saito 65 is about equal in power to a strong 46 two stroke.

What fuel are you using? What is the oil type and content?

Here are my recommendations:

15-20% nitro with 18-20% all synthetic oil, APC 12X6 prop. OS F glow plug. This should get you around 10-10.5K RPMs on the ground and should be very reliable.
Reply to
Paul McIntosh

Reply to
Mark

I have used an APC 13x6 on my Saito 65 for years. It turns about 9,300 rpms. My next favorite prop for the Saito 65 is a APC 12x7.

If the airframe is heavy or has a lot of drag then a 13x6 is a burden on the engine. But for a .40 size or lite weight .60 size plane a 13x6 is fine, if it gives you the performance that you're happy with.

4 Strokes d>Me and my Saito 65 again....
Reply to
emcook

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