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OS Max .46 SF

Old 03-09-2005, 08:47 PM
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LuckyArmpit
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Default OS Max .46 SF

Isn't the OS Max .46 SF engine a ringed engine? And wasn't it the pre-cursor to the LA line? I know a guy who may be selling one
and if the price is good, may pick it up and run it on a Sig Kougar. How comparable is it to the AX line?

Dave...
Old 03-09-2005, 08:52 PM
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Ed_Moorman
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Default RE: OS Max .46 SF

The OS .46SF was their top-of-the-line, ball bearing .46 and the forerunner of the FX series. It came in a ringed version and an ABN version. Most people opted for the ABN one, thinking it might have more power. What they got was one with a peeling liner and a ruined engine. If you find a ringed one, pick it up, it's an excellent one. Avoid the ABN one. I have one and, as I mentioned, it has a peeled liner.
Old 03-09-2005, 10:56 PM
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ho2zoo
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Default RE: OS Max .46 SF

I agree with Ed. I had the ABN version. Ran great for about 2 years- then yuck! No power, bad idle, etc. Replaced the piston and cylinder liner and it ran good for another 2 years- then yuck again! Really put me off OS for several years.

But my OS .91 Surpass (ringed) has lasted for 10+ years!
Old 03-09-2005, 10:58 PM
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Mighty Mouse-RCU
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Default RE: OS Max .46 SF

I thought it was the FX that had the peeling problem not the SF. Did they both have this problem?
Old 03-09-2005, 11:35 PM
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Default RE: OS Max .46 SF

All the OS engines with the ABN liners had this problem until late 2001.

The SF was not the fore runner of the LA series. The fore runner was the FP series of engines.

There was a guy on here the other night with a old peeled LA.

I've been around a lot of SF's and I thought they were pretty good.

Enjoy,

Jim
Old 03-09-2005, 11:45 PM
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slapshot
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Default RE: OS Max .46 SF

Ed is right, the 46 SF ringed is a great engine. I have one in a Sandich Magnum, has to be at least 10 yrs old.
Old 03-10-2005, 08:44 AM
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Default RE: OS Max .46 SF

I had a bunch of SF ABN engines & not a peeled liner to be found -- great engines. However, my first (& 2nd last) FX peeled it's liner.
Old 03-10-2005, 09:00 AM
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Default RE: OS Max .46 SF

Thanx! The engine is the ringed version. According to the guy who has it, has pretty good compression. Hope he don't change his mind though as he has acquired a 40 sized Cessna.

Dave...
Old 03-10-2005, 12:45 PM
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Default RE: OS Max .46 SF

Guys...What causes the liner to peel...improper break-in, too much heat (a little added castrol) and would the magnum liner/piston fit. I have one, now I'm leary. Thanks Dave
Old 03-10-2005, 01:56 PM
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britbrat
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Default RE: OS Max .46 SF

There is nothing inherently wrong with having a nickel-plated brass cyl sleeve, as the nickel is very much harder than the high-silicon aluminum piston -- thus making the piston the critical wear component. I suspect that the problem with OS was inadequate thickness of the copper & nickel plated layers, plus problems in surface preparation prior to plating. It could also have been compounded by the brass sleeve being too thin &/or variations in the composition of the brass alloy that was used. These faults would make the engines susceptible to thermal damage. The failure rate was fairly low, and as it would be costly to re-engineer the piston & sleeve assembly, or the manufacturing process, OS probably avoided doing anything about it --- until their reputation started to suffer.

This is all conjecture on my part, but I think that it was the real-world situation.

ABN actually works pretty well -- Thunder Tiger has much thicker nickel layers on their ABN engines & has excellent reliability & service life.
Old 03-10-2005, 03:37 PM
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Default RE: OS Max .46 SF

It was my understanding that OS didn't copper plate prior to the ABL process. I could be wrong on this.

If you went back to the old RC Online, which imploded due to poor software, there were threads miles long on peeling OS .46 SFs & FXs. People were cussing OS left & right. They had to make a change.

As someone has mentioned, there were some fliers who never had a peeling problem. It seemed to me like these were in the minority, although the ones with the problem were naturally the most vocal.

The .91s, both 2 & 4-strokes were ringed engines so they wouldn't have this problem. The .91FX did have a leak, or somethng, with their remote needle valve. They have since replaced the needle with an assembly with one like that on the AX which works very well.
Old 09-11-2019, 06:49 AM
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Interesting that people were having problems with the ABN version. I just changed the bearings in my 35 or so year old ringless .46 and the sleeve was fine. Did they make improvements? I'll report back in another 35 years.
Old 09-11-2019, 10:17 AM
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Where's Konrad when we need him ?

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