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OS 46 FX problems?

Old 07-02-2002, 04:07 AM
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Default OS 46 FX problems?

First a little history about my OS 46 FX. Last fall it was in my LT-40 with about 20 flights on it when I crashed 80 feet up in a tree. There it stayed for 2 weeks. It rained once or twice and the temperature was very near freezing a few nights, but I don't think it ever went below the freezing point. When I finally got it down, the engine was fine. I then put it into my Super Sportster 40. I had to swap the carburator and backplate of my OS 40 SF to get it to fit properly. On its very next flight, a blind dead stick landing left me without any flyable planes. But the OS 46 FX still looked good. I put a few drops after-run engine oil in it, turned the prop a few times, and it sat in a closet.

About 8 months later, it is in my Super Sportster 40 again. I noticed that while turning the prop by hand, I can hear, but not really feel, that it wasn't as smooth as before (this is my first problem). Yesterday, I ran a tank of 10% nitro through it just to make sure it's still okay. I ran it very rich and all seemed good.

Today, I wanted to fly it. I started the engine and it ran for about 30 seconds before it quit. At this point, when I turn the prop there seemed to be very little compression, almost none (this is my second problem). The ball bearings still sounded not-quite-right. After the engine had a chance to cool down, a wiser and more experienced guy came to help and noticed that both my high and low needle settings were both WAY off. Maybe the engine likes it better when someone with experience touches it, because he did not notice any lack of compression. He fiddled around, got the engine running very good, and I had a very good first-flight-after-major-repairs.

Post flight inspections reveals that both my problems seemed to have gone away. It seems too good to be true and I'm a little skeptical.

I can understand the ball bearing problem. Maybe they just needed 2 tanks worth of fuel to get them well lubricated again. But how can compression suddenly disappear and shortly after reappear? This is what I'm really nervous about. Is there something that I should do or check?

Sorry for the wordiness. Thanks in advance.

Old 07-02-2002, 12:53 PM
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Default OS 46 FX problems?

I'm not sure exactly what all happened with your engine. I would really recommend having it checked up/tested prior to continuing to fly it for fear of losing yet more aircraft with this weatherbeaten baby!

Please visit for a service worksheet and information to ease the process of sending your items for service.

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with a brief letter describing the problem you have had and include your proof of purchase and a copy of your receipt from purchase. Our staff will inspect your product and will notify you regarding their findings. If it is found to be a warranty defect, the product will be repaired or replaced at our option at no cost to you. If it is not a failure covered under warranty, you will be notified of your options for return, repair or replacement. Thank you for your patience and, of course, your business.
Old 07-02-2002, 04:45 PM
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Default OS 46 FX problems?

If the throttle was closed all the way, the engine cannot suck alot of air into it and the compression will not feel as good.
Hope this helps.
Old 07-22-2002, 12:22 AM
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Default OS 46 FX problems?

I was retuning my OS 25 FX today and when I went to start it it made a clunk noise and had the same syptom of very little compression, My brother that was very big into RC cars a while back helped me figure it out. You needle valves being out makes sence to this, My engine was completely flooded top and bottom explaining the clunk noise with all the fuel in the bottom of the cylender and in the top was not allowing air to get in to compress so it seemed to have no compresion, I took out the glow plug and turned it over (fuel line disconnected ) and blew out all the fuel and the compression was back to where it should be (Thank God it is only a few months old) It sure is strange the things these little engines do. Hope this helps explain what might have been wrong.


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