After run oil or Rust?
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After run oil or Rust?
There is a ton of oil in it, and there is definitely some rust, does it look bad?
I picked this motor up on ebay used, it looks new on the outside, the piston looks new, you can tell the motor has never been mounted on a plane, only a test stand.
I'm thinking it's seen maybe 10 ounces of fuel on a stand then got thrown on a shelf for the last couple years.
This is a OS 91fx
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That appears to be mostly dried castor, my guess is that the bearing balls are stuck in the cage and will be hard to get loose. If you are adept at changing bearings I'd change them.
https://www.bocabearings.com/product...=FX&feature=91
https://www.bocabearings.com/product...=FX&feature=91
Last edited by Hobbsy; 11-29-2016 at 04:41 AM.
#5
Just soak it in some fuel and check the bearings after. My experience is that there is usually no rust when covered in castor varnish as this appears to be. But not always. Most likely the bearings will be fine after dissolving the dried castor oil and varnish. Anti freeze would work also but be sure it is well oiled after flushing it out.
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Well the motor does spin freely, actually before I took the back plate off the motor felt great just spinning the crank, last night I sprayed the heck out of it with PB penetrating lube before putting the backplate back on, when I get the time I'll tear it down completely.
Thanks for all the advise guys.
Thanks for all the advise guys.
#11
I've gotten several "lightly used" engines that looked similar or worse than the engine pictured above. I personally use a regimen of acetone soaking for 30-60mins, blow out with air, rinse with acetone again, blow off with air, and add oil. At this point if the bearings feel pretty smooth, I'll run it and check the bearings after a few tanks of fuel. If not butter smooth (or rather - if they make any noise whatsoever, I replace the bearings.
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I've gotten several "lightly used" engines that looked similar or worse than the engine pictured above. I personally use a regimen of acetone soaking for 30-60mins, blow out with air, rinse with acetone again, blow off with air, and add oil. At this point if the bearings feel pretty smooth, I'll run it and check the bearings after a few tanks of fuel. If not butter smooth (or rather - if they make any noise whatsoever, I replace the bearings.
Last edited by Dealspeed; 11-29-2016 at 01:00 PM.
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Antifreeze works pretty good but it can't be the premixed Antifreeze, it has to be the concentrate, it has a certain ingredient in it that the premix doesn't have.
#17
Glow fuel works fine for oil and residue, but only to a point. Acetone works much better for dissolving the varnish I've found. The crockpot antifreeze trick works well, but it has to be heated and given at least 6-8hrs to do its best work. Most guys use the green Ethylene Glycol undiluted, but some have had success with the extended life types (propylene glycol). Either method will require complete removal of the solvent, drying, and oiling immediately.
Ive had great success with engine bearings from rcbearings.com and equal success using bearings from AvidRC.com as well. Avid is dirt cheap ($1 each) and seem to be identical in every way to what RCBearings sells (which are the same thing as Boca's econo bearing sets). If you use coupon code "shout" you get 5% off your order or "RCU" for 7% off your order at RCBearings.com.
Ive had great success with engine bearings from rcbearings.com and equal success using bearings from AvidRC.com as well. Avid is dirt cheap ($1 each) and seem to be identical in every way to what RCBearings sells (which are the same thing as Boca's econo bearing sets). If you use coupon code "shout" you get 5% off your order or "RCU" for 7% off your order at RCBearings.com.
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I ordered a set of bearings on eBay for the 91 for $12 there Abec 3 direct replacement, surprisingly Boca bearings didn't sell any for the 91fx, it wasn't even listed, plus they are exspensive at $50 for a OS 25fx bearing set, seem pretty steep to me.
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Just bought another used motor, this time from the RCU marketplace, it's one of the better 91 two strokes as far as power to weight ratio, It's the Evolution .91nx, has a total weight with muffler of 20 ounces.
i just hope this motor doesn't look like my 91fx inside.
i just hope this motor doesn't look like my 91fx inside.
#23
Glow fuel works fine for oil and residue, but only to a point. Acetone works much better for dissolving the varnish I've found. The crockpot antifreeze trick works well, but it has to be heated and given at least 6-8hrs to do its best work. Most guys use the green Ethylene Glycol undiluted, but some have had success with the extended life types (propylene glycol). Either method will require complete removal of the solvent, drying, and oiling immediately.
Ive had great success with engine bearings from rcbearings.com and equal success using bearings from AvidRC.com as well. Avid is dirt cheap ($1 each) and seem to be identical in every way to what RCBearings sells (which are the same thing as Boca's econo bearing sets). If you use coupon code "shout" you get 5% off your order or "RCU" for 7% off your order at RCBearings.com.
Ive had great success with engine bearings from rcbearings.com and equal success using bearings from AvidRC.com as well. Avid is dirt cheap ($1 each) and seem to be identical in every way to what RCBearings sells (which are the same thing as Boca's econo bearing sets). If you use coupon code "shout" you get 5% off your order or "RCU" for 7% off your order at RCBearings.com.
Last edited by Sport_Pilot; 11-30-2016 at 04:20 AM.
#24
#25
Since methanol will eat up rubber glow engines do not have rubber parts. Go back to the gas engine forum and quite pretending to know glow engines.