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HomeAircraftHelicopterBeginners Corner › motors and bearings
02-09-2006 03:25 AM  12 years agoPost 1
fly-en

rrApprentice

Groveport, Ohio

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how long are the bearings suppose to last. I got my ys 91 in nov. I pulled it apart just to check things out and it looked like the rear bearing was rusted. Is this suppose to happen? How do you keep the motor from doing this. Would ceramic bearings help. Ys 91 and hyper 50. Rappy man.

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02-09-2006 08:27 AM  12 years agoPost 2
Andreas

rrVeteran

Sweden

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Hi.

I have to change my rear YS bearing after about 50-60 litres (15 gallons) of fuel. I haven't tried the cheramic bearing yet but i think i will next time my bearing fail.

Andreas

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02-09-2006 09:08 AM  12 years agoPost 3
Raptor3DPilot

rrKey Veteran

North Las Vegas, NV

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Fly-en,

http://www.RC-Bearings.com has some great prices on ceramic bearings.

Remember when flying inverted that down is up and up is EXPENSIVE!

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02-09-2006 09:35 AM  12 years agoPost 4
Yug

rrMaster

UK. Herts

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All bearings go rusty in the end due to the acidic products from burnt fuel. I've found ceramics rust just as easily as normal bearings. I have also found an improvement if the fuel system is pressururised by the crank rather than muffler pressure as this results in the acidic gasses not returning to the fuel.
Bearing life time can vary alot. My Hyper50 lasted a year with about 400 flights on it using standard bearings. I've had a OS91 last just a few gallons with ceramics. Fuel absorbs moisture so at the end of a session, I run the engine till it stops then turn over for a second or 2 to remove any unburnt fuel.

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02-09-2006 11:24 AM  12 years agoPost 5
fly-en

rrApprentice

Groveport, Ohio

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Guy, Is there a certain brand of fuel to help keep this from happing. I have been using wild cat fuel, and honestly I nervous about this happening again. I will try your technique out (letting the fuel burn out), then turning the motor over to get the remaining fuel out. Will let you know how it goes.

thanks fly en

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02-09-2006 11:37 AM  12 years agoPost 6
Yug

rrMaster

UK. Herts

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I think all brands of fuel do this to a greater or lesser degree. Some have rust inhibiters etc etc. At the end of the day, I tend to think it's more down to the nitro content because the nitro breaks down to nitric acid which is good at rusting steel. Plank flyers don't tend to suffer rusty bearings in the same way helis do which, I attribute to them running lower nitro contents.
With regards to which fuel is better, each will argue their case and this sort of thing (particularly on RR) turns into a slagging match.
Do a search on RR - there is lots of info here, but be warned, the arguments get ugly .
My personal fuel preference is currently Magnum30. This has plenty of oil and my engines seem to run fine. I used to use Coolpower20, which again was fine. My reason for Magnum30 is that the oil content is good which helps sustain engine life, plus plenty of smoke which looks good, and, it's a reasonable price (if there is such a thing with high nitro fuels). I'm afraid I can't comment on wildcat as I haven't tried it. Get searching and reading - good luck

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02-09-2006 12:56 PM  12 years agoPost 7
airdodger

rrElite Veteran

Johnston USA

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http://web.archive.org/web/20040301....com/facts3.htm Read the part about acid forming, about the sixth paragraph up from the bottom. Chris

Chris

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02-09-2006 01:10 PM  12 years agoPost 8
MattJen

rrElite Veteran

UK

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All bearings as posters have said will go,
the fuel we use attracts moisture,

the key is to prolong your bearing by running the engine dry at the end of each flying session and then turn the engine fan untill compresses, this will stop moisture from getting into the engine when storing.

i have a YS91 and have replaced the bearings twice this year, some i know have never had to replace them others have had a bearing go in a month.

I would stay away from ceramic, this is my opinion only,

the reason i feel is they are too hard, the piston is constantly bainging against them whilst running and eventually they shatter knackering the engine, whereas the metal bearings are slightly softer and give you a rattling warning when they are going rather than just shattering.

that is my experience only, i know some have never had to replace ceramics, but in my experince i dont like them.

All The Best

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02-09-2006 01:25 PM  12 years agoPost 9
fly-en

rrApprentice

Groveport, Ohio

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airdodger,
Great article, it explained alot.

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02-09-2006 02:30 PM  12 years agoPost 10
tchavei

rrProfessor

Portugal

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I'm in the same boat. I don't think runtime matters as much as time on the shelf.

I have a brand new Ys91 (maximum 5 flights on it) that has been sitting in my Freya for about 3 months (I flew the evo 50 in the meanwhile). The other day I stripped the engine because we have high humidity at this time of year (60-70%) and behold... the outer cage of the rear bearing had some rust signs and brown mud around it (progress of rust forming). I had to clean the whole mess and thankfully I didn't find any structural rust just some little marks on the outer cage. I now have started to use after run oil. Even if expensive its cheaper than buying new bearings every 5 flights...


Tony


--------------------
"Perfection and patience usually walk side by side..."

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02-09-2006 07:43 PM  12 years agoPost 11
fly-en

rrApprentice

Groveport, Ohio

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tchavi,

I'm glad you wrote that thread, I was beginning to think I was doing something wrong. It seems you caught your problem before it became a problem. For me that is not the case, I had to buy new bearings. This time I went with the ceramic bearing. Will see if it makes that much of a difference? I'm also going to change the fuel from wild cat to maybe cool power or Curtis’s brand of fuel.

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02-09-2006 10:35 PM  12 years agoPost 12
tchavei

rrProfessor

Portugal

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Things I'm going to do from now on the last flight:

1. Spool down with engine running
2. clip off the fuel supply and as engine revs up, throttle cut.
3. depressurise tank
4. put remote glow and turn the engine until it doesn't pop anymore
5. inject 1 ml afterun oil thru the backplate plug
6. turn the engine a couple of times with the starter
7. put cylinder in top compression position
8. put pressure line on
9. plug the exhaust

I hope bearings will live longer

Tony


--------------------
"Perfection and patience usually walk side by side..."

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02-09-2006 10:50 PM  12 years agoPost 13
fly-en

rrApprentice

Groveport, Ohio

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tchavei

Thanks to who ever came up with cut and paste. I now have my post flight check list.

fly en

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02-09-2006 11:11 PM  12 years agoPost 14
tchavei

rrProfessor

Portugal

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hehehe

You're welcome!

Tony


--------------------
"Perfection and patience usually walk side by side..."

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02-10-2006 04:20 AM  12 years agoPost 15
medfoch

rrApprentice

Bay Village, Ohio

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A couple of thoughts -

When you run the engine dry - do NOT clamp the fuel line - simply pull it off - if you clamp it you will create a vaccuum in the carb and you will NOT burn all the fuel. Once the engine does die there is still more in there - put the glow ignighter back on the glow plug and try to start the engine again. You will see that the enging will start again - just keep the engine turning over until it is completly DEAD - about 10 - 20 sec.

I am not sure exactly how much 10 ML is, however the average bottle of after run oil should only last about 6 or 7 uses - I think I got this from Curtis YoungBloods web site in the Ask Curtis section. I used to have rusty bearings - now using about 1/6 the bottle incerted through the back plate I have NO rust on either of my engines - each with cases of fuel through them. I only use the after run oil if I am not going to be able to fly for more than a couple of days - if you are going to fly the next day or day after there is really no need to use the oil - just run the engine dry.

Good Luck

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02-10-2006 04:36 AM  12 years agoPost 16
ESWLFSE

rrElite Veteran

Liberty Hill, TX

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Does after-run even get to the bearings if it is added to the crankcase from the backplate with the crank up as in a heli? Would it be better to inject it into the carb through the needle with a syringe and a length of fuel tubing? Or should the heli be cranked inverted to distribute oil to the rear bearing?

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02-10-2006 11:48 AM  12 years agoPost 17
tchavei

rrProfessor

Portugal

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the problem injecting it through the carb are the silicon components of the YS... regulator/o-rings etc

The back of the crankcase seems to be the most direct path to the rear bearing and if you put the bird nose up (vertical) while injecting the oil goes strait onto the bearing (and doesn't come out again thru the hole.

A bottle of 50ml gives you how many uses? I'm puting only 1 or 2ml oil which seems enough (I checked with the backplate removed) as it oils the bearing completely but doesn't flood the crankcase.

Tony


--------------------
"Perfection and patience usually walk side by side..."

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02-10-2006 01:43 PM  12 years agoPost 18
Doug

rrElite Veteran

Port Saint Luice Florida....

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The main culprit in promoting rust is the exhaust left in the engine and muffler at the end of the day. If you will motor the engine with the starter at WOT for about 30 sec it makes a world of difference. There is no better "after run" oil than fuel with a little castor in it run through after your last flight (I hover out a header tank full at the end of the day) and have zero corrosion (even in SW florida with the machines outside all year.

First member of Member of Bearings Anonymous

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02-10-2006 06:24 PM  12 years agoPost 19
MattJen

rrElite Veteran

UK

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here is my bearing after 2 months,

i have since got an exhaust plug, and always make sure i run engine dry as posters have said, good advice that will prolong your engine

Matt

All The Best

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02-11-2006 05:08 AM  12 years agoPost 20
medfoch

rrApprentice

Bay Village, Ohio

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I can agree with the caster oil - I have a .32 that is about 10 years old that I quit using 5 years ago that I only ran caster in - NO RUST!! - after run oil seems the best solution now since all the good heli fuels only run synthetic...

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