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Old Sep 12, 2010, 09:11 AM
Fly'em like you Stole'em
MikeMcChiken's Avatar
The Gehto,Ca.
Joined Jun 2008
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I Tober ,

I am just wondering how you can go 18 yrs without replacing bearings in any motors . Hand it I have replaced bearings that didnt need it . They feel worn but when you get them out of the motor they feel fine . Maybe I am just too picky or all your motors are older with a better quality bearing in them ?

I also was wondering on this oil % . I have a friend that is running a .62 on a Primo 40 . He runs Coopers fuel in it at 30% nitro and 12% oil . He has run it for 3-4yrs now . Said the 18% is BS and not neccesary if the mix is with top notch oil and additives . How can I argue when his motor runs like a top ?
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Old Sep 12, 2010, 02:30 PM
Talk soft, carry a big plane.
maxadventure's Avatar
northern colorado
Joined Jul 2007
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Quote:
Originally Posted by MikeMcChiken View Post
I Tober ,

I am just wondering how you can go 18 yrs without replacing bearings in any motors .
An individuals perspective. I have a Saito .65 I put in my cub around 1990. That engine may have burned a gallon a fuel - absolutely less than 2 gallons. I never flew it while in college, or when I lived in other states for years at a time. I read about guys blowing threw a case of fuel a month during flying season and I have no idea how they have the time. I think I've only flown that plane twice so far this season, even though I had planned to float fly every week or two this year *sigh*. Maybe when IBM lays me off to hire in India I'll have more time!

at any rate, I read these stories of bearing replacements and how do you really know how many hours at what oil percentage etc are on the engine? I certainly don't track mine that close.
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Old Sep 12, 2010, 02:30 PM
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USA, MA, Weymouth
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The FHS Red Max fuel I've used has ALWAYS been kind to my "mills"...

Dear Fellow Saito Lovers:

The PIPE Here again...it's the fuel whose price list is at http://www.fhsoils.com/model_prices.html that I've used since the mid-1980s, and FHS Red Max fuels have ALWAYS treated the "innards" of my four-stroker mills quite well.

My usual four stroke custom "mix" from them has been a 17% all-synthetic oil, 10% nitro mix, which I've still got a gallon's worth in storage from at least seven years ago, all sealed up in a set of never-opened, set of four one quart plastic bottles here in my basement.

Just to be certain things inside my four-strokes will last over the long haul, though, I also got into the practice of using Marvel Air Tool Oil in my four strokers a long time ago as well, to "pickle" then in for storage, and as an after-run oil.

Now, with that brand new FA-40a of mine needing to get CAD-drawn up for something to refer to as I continue to computer-draw up the planset for a new 42" wingspan Jungmeister bipe to have fun with once more, a bit down the pike time-wise, when IT gets broken in on my test stand, the FHS Red Max fuel and Marvel Air Tool Oil are things it will get to know quite well, just like all my other 4-stroke mills.

That FHS Red Max fuel HAS worked quite well for me, for a very long time..!!

Yours Sincerely,

The PIPE....!!
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Old Sep 12, 2010, 02:45 PM
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Quote:
Originally Posted by maxadventure View Post
An individuals perspective. I have a Saito .65 I put in my cub around 1990. That engine may have burned a gallon a fuel - absolutely less than 2 gallons. I never flew it while in college, or when I lived in other states for years at a time. I read about guys blowing threw a case of fuel a month during flying season and I have no idea how they have the time. I think I've only flown that plane twice so far this season, even though I had planned to float fly every week or two this year *sigh*. Maybe when IBM lays me off to hire in India I'll have more time!

at any rate, I read these stories of bearing replacements and how do you really know how many hours at what oil percentage etc are on the engine? I certainly don't track mine that close.
That must be why we hear all the rust stories with some ." A running engine gathers no rust ".
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Old Sep 12, 2010, 05:13 PM
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I have some OS45 FSR's and 61 FSR's that I bought in the late 70's, early 80's that have never needed new bearings and they were run many many hours. They were/are run on mild fuel (10% nitro) and 20% castor oil. While I have worn a few bearings out, it usually took a couple hundred hours. Most were replaced because of rust which is the number one reason for bearing replacement. At least that's what I've seen. The use of castor based fuel will all but eliminate rust.

Each of my airplanes has a little notebook where I keep track of the number of flights and when it was flown and when it was built. My dad got me into that habit.
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Old Sep 12, 2010, 10:26 PM
Fly'em like you Stole'em
MikeMcChiken's Avatar
The Gehto,Ca.
Joined Jun 2008
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I'm thinking high nitro might be contributing to the bearing issues . A lot of you guys run 10-15%. I ran 20-25% now 30%heli with 20% synthetic . I can definately notice a power difference . But nitro after burnt , I heard , turns into nitric acid . With steel bearings and higher nitro , maybe the level of wear is higher .

I have an old .25FSR and a FP-40 I would like to get back to running condition again .
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Old Sep 12, 2010, 11:10 PM
oldsapper
Barossa Valley Sth Aust
Joined Sep 2009
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I'm in with both feet.....I have a 62 and an 82. the latter I bought 2nd hand from a bloke who said it had hardly done any work, runs fine, but is leaking a little fuel from around the prop shaft bearing. Would replacing the bearing sort this prob?
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Old Sep 12, 2010, 11:20 PM
Expo is built into my thumbs
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USA, ID, Niter
Joined Jul 2008
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I put a couple of flights on my ultra stick 60 satio 100 combo. Both were dead stick landings my first in ten years. No big deal I glided in for a perfect landing both times. I was running way rich to be on the safe side because the engine isn't completely broke in yet. I might want to lean it out a bit though lol.
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Old Sep 12, 2010, 11:24 PM
It's Prime Time for Slime Time
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Originally Posted by olddig View Post
I'm in with both feet.....I have a 62 and an 82. the latter I bought 2nd hand from a bloke who said it had hardly done any work, runs fine, but is leaking a little fuel from around the prop shaft bearing. Would replacing the bearing sort this prob?
Fuel? Or oil? Oil is not a big deal. (there shouldn't be raw fuel coming out of the front bearing!) If you must, then replacing the shield on the front bearing will most likely solve your problem. Replacing the whole bearing is going too far unless there's noticeable play.
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Old Sep 12, 2010, 11:29 PM
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The nitromethane turning into nitric acid during combustion is an old modeling wive's tale. I ran boat engines on as much as 50% nitro and never rusted bearings. The high nitro use was when I did wear out bearings from the high rpm we turned boat engines. I used castor based fuel and never had rusted bearings.

Did discover one thing. The amount of power gain using 50% nitro was more than made up by driving ability when using 25% nitro. The engines and bearings did last considerably longer using lower nitro. Especially the lower end of the conrod.

A shielded bearing will not stop fuel from coming out the front end of an engine. All a shield does is keep dirt out of the bearing. It isn't a seal. The front seal on a two cycle engine is the crankshaft to crankcase fit. Even the sealed bearing won't stop fuel from leaking out the front end. Also, there must be some leakage out the front end. How do you think the front bearing gets lubricated? Same for a bushed crankshaft. Many Super Tigres don't have any shield or seal on their front bearing. They come that way.
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Old Sep 13, 2010, 07:07 AM
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Quote:
Originally Posted by iluv2fli View Post
All a shield does is keep dirt out of the bearing. It isn't a seal. The front seal on a two cycle engine is the crankshaft to crankcase fit.
This thread is about Saito four strokes. A sealed bearing really is all it takes to keep the oil in the engine.

Greg
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Old Sep 13, 2010, 07:34 AM
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Mike, its pretty easy, I've stated several times on the other network that most bearings are replaced for imagined reasons more often than real reasons. I've seen guys claim that they replaced bearings on a fourstroke because the fuel mixture changed, not going to happen on a fourstroke unless its a YS. This Enya .46MKII is my highest time engine and still has its original glow plug so I don't buy into the theory that "break in" ruins glow plugs. This was by the way my very first rc engine in 1990. I partly learned to fly with this engine on a Kombat 40 with the 60" wing option. Most people who saw that combination said it couldn't fly but it flew very well. It flew its first two seasons on Fox 15% fuel with 20% castor, that was supposed to ruin it but didn't. I don't bother to "myth bust" very often but watching the BS roll by gets tiresome at times.

This Saito is a high compression one from the 80s and has flown in Ohio, Pa., Maryland, W.Va and Va. It will run on Davis Diesel fuel unaided. Its all original except the upgraded spraybar. The .80 is the taller one beside the .82.
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Old Sep 13, 2010, 01:49 PM
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Quote:
Originally Posted by gkamysz View Post
This thread is about Saito four strokes. A sealed bearing really is all it takes to keep the oil in the engine.

Greg
Actually you want all that oil OUT of the engine. That's why there is a breather. A little leakage through the front bearing guarantees it will be lubricated.
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Old Sep 13, 2010, 02:17 PM
It's Prime Time for Slime Time
b7gwap's Avatar
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Quote:
Originally Posted by iluv2fli View Post
A shielded bearing will not stop fuel from coming out the front end of an engine.
Um, again, hopefully there is no fuel coming out anywhere in the bottom end. It only belongs on the upper side of the rings. A little blowby is expected and necessary for lube, but there should be mostly oil in the bottom end.


Quote:
Originally Posted by iluv2fli View Post
All a shield does is keep dirt out of the bearing. It isn't a seal.
Um, actually it is a seal. That's why they're called sealed bearings.

Quote:
Originally Posted by iluv2fli View Post
The front seal on a two cycle engine is the crankshaft to crankcase fit.
Right, but the Saito in question is a four stroke, so..

Quote:
Originally Posted by iluv2fli View Post
Even the sealed bearing won't stop fuel from leaking out the front end.
Not if it's compromised, no. If it's intact, it should.

Quote:
Originally Posted by iluv2fli View Post
Also, there must be some leakage out the front end.
Not necessarily, actually.

Quote:
Originally Posted by iluv2fli View Post
How do you think the front bearing gets lubricated?
From the oil in the bottom end of the engine? Just because it doesn't pass through the front bearing doesn't mean it's not getting to it. If there's oil coming out the breather, then your bearings are getting lubed, even with a dry exterior on the front bearing.

Quote:
Originally Posted by iluv2fli View Post
Same for a bushed crankshaft. Many Super Tigres don't have any shield or seal on their front bearing. They come that way.
Okay, but again, STs are two strokes, so..
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Old Sep 13, 2010, 03:44 PM
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[QUOTE=b7gwap;16038135]

Um, actually it is a seal. That's why they're called sealed bearings.

There is a HUGE difference between a sealed bearing and a shielded bearing. A sealed bearing has a rubber seal and a shielded bearing has a metal shield. The shield will not stop the flow of any liquid. A seal will at low pressures but it will pass liquids at a higher pressure. If you squirt wd-40 or any other product like that into a Saito breather it will come out the front bearing whether sealed or not. I've done it many times and that does not damage the seal. Even a small syringe full of oil will squirt oil past a sealed bearing.

Most of my Saitos, and I have a bunch, have shielded front bearings.

Bearing on the left is a shielded bearing. One on right is a sealed bearing completely different. The two engines are a Saito 80T and a 90T. Both have a shielded bearing and are original. Both leak a bit of oil and stay lubricated.
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