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Engine basics => Engine set up tips => Topic started by: Peter in Fairfax, VA on August 07, 2020, 08:21:40 AM
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How important are smooth bearings?
In my work selling model engine collections, I've encountered a number of engines that have a slight roughness in the bearings. This has been with various engines, and is not specific to a brand. Super Tigre, O.S., Ross, etc. Though I do my best to note this to buyers, I've had at least one engine returned.
I suspect the cause of the roughness, what you might call a "notching," is rust or possibly even congealed oil. Often it disappears when the engine is warm, returns cold.
Recently I've been evaluating an O.S. SF 46 with the standard R/C "SF" crank timing. It has a slight roughness in the bearings. Yet, it starts and runs great, based on test stand runs. Should I be concerned about the bearings or just run it?
thanks,
Peter
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Bearings are pretty cheap. If they come apart & the races or any other thin metal gets stuck between the piston & liner you will be in trouble... ask me how I know this. Lost a terrific SSW Magnum .53 from a bad bearing.
John L.
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bearings are cheap but dont use cheap bearings. most older motors have been run on mostly caster based fuels and if not run for a length of time the bearings will gum up.newer motors that have been run on synthetic oil ,the bearings can rust up if after oil is not used.
i feel that any motor that has not been run for a year or more should at least have the backplate removed and any crud flushed out and the rear bearing inspected and flushed out with carb cleaner or some other solvent.S/T rods seem to stick to the wristpin then all the wear is on the wristpin and piston.
most cheap bearings are made with a brass bearing retainers ,after time the tabs can break off and go through the motor doing major damage. better bearings have better retainers that should last the life of the motor.
a long storey but i have real life proof that Japanese bearings are superior to Chinese bearings
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Bob ,
I have proof of the same when changing out bearings in my Tiger .60s the Chinese stuff was loose , etc the Jananese, German ,French & Italian bearing ALWAYS fit.
John L.
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Never run an engine with rough feeling bearings, the bearings will shed small parts of whatever the roughness is.... rust, solid dried oil, corrosions etc, and then it will run thru the piston and sleeve
Randy
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apparently , small bearing particals hit the glow plug element , and it shuts off .
Bin meaningto pick up a new set for my SF46 clone . Threw a better used set in, but still worried itll do it .
Nitro coroded aqncient bearings are liable to loosen up real fast .
My 46 on 15 % nitro , intake measured .290 with a new battery in the virneer :P 9 mm odd Enya one
4 stokes nicely on a 12 x 6 . just put it back in the Strega , butll have to come out to throw a ounce of noseweight in.
Then itll only be 86 ounce ! Handles it well though .Royal 46 ABC .
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Running rough/pitted bearings is rolling the dice. If you wait too long before changing bearings it destroys the engine. I had it happen on a Kraft 60 while on the test stand and took about one second to go from smooth running to massive vibration and a full stop. Case, crank, piston, rod, liner, back plate, head hammered to death and BOTH bearings in pieces.
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I have been using bearings from this company for quite a few years now with no problems: http://www.rcbearings.com/os-0-59-engine-bearing-sets/?sort=featured&page=2 At their prices, it's hard to justify not changing questionable bearings.
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multiple bearing types for just about ant engine. been using them for years and not just for model engines.
https://www.bocabearings.com/?gclid=CjwKCAjw4MP5BRBtEiwASfwAL0sTWtcDLGrEdypTidEamu48GGv9csmm3wTqaYKmkIUB-uJGxzIqbBoCNsgQAvD_BwE