Conference vmszoo::rc

Mike

<  I had it rust up on me within a week

What type of acid did you use as fuel?, I would suggest you change  or get a
good after run oil.Cant say I have ever replaced a bearing in a .25FSR but as I
recall it is not too different to .40 in the engine construction; that is
removable front housing and a cone locking prop back plate. 

1. Remove the aluminum prop back plate with a small wheel puller or an OS 
   puller (Part No ????). The Crank should then slide out.

2. Place the front housing in boiling water for 5 mins. The coefficient of   
   expansion of aluminum is greater than steel, the bearings become loose 
   and can be taped out. 

3. Replace the bearings with care so as not to skew them when pressing them 
   into the housing.

John.

    Kay,
    
    I don't know much about dissassembling engines so I can't help you
    there.
    
    On cleaning the outside, I know your not supposed to use oven cleaner
    as it eats aluminum.  You my try aluminum jelly, but test first.
    You have to degrease engine before you use it.
    
    Also, LONG and SHORT glow plugs have different length threads.
    I believe .10/15 engines use "short" plugs.  .20 and up use "long".
    I don't believe the Idle bar should determine if you should use
    long or short.  All the idle bar does is keep the fuel splash from
    extinguishing the glow at low RPM (idle).

    The play in your crank is most likely wear in the wrist pin holes
    in the piston and not wear of the pin itself.  The pin is usually
    hardened steel and the piston is usually aluminum.  The rod top
    end suffers first from lack of lubrication in many engines.
    I had this happen in my OS40 FSR.
    
    Replacing the piston is fairly easy to do if you are careful to
    keep things clean and don't overtouque screws and bolts on reassembly.
    The most difficult thing to do with two stroke engines is replacing
    the ball bearings on the crankshaft.  This usually requires a special
    tool to press off the prop drive washer in order to remove the crank.
    I bring mine into our machine shop and use a small press.  The other
    difficult thing is removing the bearings from the aluminum crankcase
    housing.  They are a press fit on most engines.  To do this, you
    need to heat the aluminum case with a heat gun to expand it.  Do
    this when you remove the old bearing and when you install the new
    ones.  Make sure that you clean everything carefully before
    reassembling anything.  When pressing in the new bearings (into
    the hot case), make sure that they start straight and do not get
    cocked.  I put the bearing on a clean flat surface and press the
    case straight over the bearing.  DO NOT push on the inner race to
    seat the bearing or you will flat-spot the balls and races and ruin
    them.  After installing new bearings, lubricate everything with
    light oil before reassembling the crank, piston, and sleeve.
    Make sure that you get the sleeve in exactly lined up with the exhaust
    port.  If you don't do this or put it in backwards, your engine
    will run like SH**.  If your piston has a ring on it, it will also
    have a small pin to keep the piston ring from rotating in the groove.
    This is to keep the ring ends from getting caught in the ports in
    the sleeve.  Make sure that the ring ends are over this pin when
    you insert the piston into the sleeve.  Also, when removing the
    piston, make sure that you mark it as to which way it comes out.
    IT DOES MAKE A DIFFERENCE!  Tighten all screws evenly first just
    snug and then torque them up in stages.  On the head, go back and
    forth across the head and not around as you tighten the screws.
    This assures an even clamping force on the sleeve.
    	If you disassemble an engine and replace any parts, treat it
    like a new one and break it in.  For this reason, don't disassemble
    your engine unless it needs it.  Parts tend to take a set and wear
    in during running and you disturb this when you take things apart.
    	Again, do all work in a clean area!  I clean up all of the parts,
    wash up the bench, wash my hands, and then reassemble.  If your
    parts lay around while you are waiting for repair parts, clean them
    in solvent before reassembling them.
    
    	I just tried some cleaner that was recommended in RCM for removing
    gunk that has cooked on my engine.  It is an aluminum cleaner made
    by Sunbeam for cleaning electric fry pans etc.  It seems to work
    better than anything else I have tried.  I don't know how long you
    can leave it on without risking etching the aluminum.
    
    Hope this is useful to someone,
    
    Charlie
    

Kay,

> I've never taken one of these apart before.
> So where do I start.  I assume that taking the
> head off won't get me far.  Removing the prop
> and back plate probably won't gain much.

The "first" thing you've gotta' do is determine, up front, before picking up the
first tool, "to KEEP TRACK of the way things come apart!" I use a small jewelers
file or even an X-Acto knife to scribe reference marks on all mating parts "be-
fore" disassembly.  You'll want to make alignment marks on such things as cylin-
der head-to-cylinder, cylinder liner [sleeve]-to-cylinder, backplate-to-crank-
case etc. to assure that proper alignment of intake/exhaust ports, combustion 
chamber baffle [if applicable], piston fence, etc. can be re-established during
reassembly.  Mark anything/everything that looks like it could be assembled more
than one way so you'll KNOW which way is correct at reassembly time.  Failure to
do this [and relultant improper reassembly] will cause you more grief than I 
care to expand upon and may physically damage the engine in the bargain.

Pulling the head is the first step but, as you've already surmised, this is only
the beginning.  Mark and remove the head, backplate and all propellor hardware.
Now check the connecting rod to determine if there's enough fore/aft end play to
slide the rod off the crankpin.  Some smaller/simpler engines are so configured
and will allow the piston to be removed out the top of the cylinder without fur-
ther disassembly.  Be careful; don't force anything or scar it up with pilers or
other such tools.  If sufficuent play is not available to slide the rod off the
crankpin, the cylinder liner [sleeve] will have to be removed.  Mark it relative
to the top of the cylinder and push up on the skirt of the liner from the inside
of the backplate.  If the fit is too tight, place the entire engine in the oven
or play a propane torch over the cooling-fin area of the cylinder `til the un-
even expansion of the dissimilar metals allows the liner to be slid out the top
of the cylinder. IMPORTANT: use only enough heat to accomplish the task...DO NOT
OVERHEAT!!!

There should now be enough play available to slide the rod off the crankpin and
remove the piston/rod assy. out the top of the cylinder.  In some engines, this
will not be the case; look for a hole through the front or back of the cylinder
...this hole is provided to remove the wrist-pin, then the piston can be removed
out the top and the rod can finally be slid off the crankpin and removed.

NOTE: THE DISASSEMBLY STEPS DESCRIBED IN THE FOLLOWING PARAGRAPH ARE NOT RECOM-
MENDED TO BE PERFORMED WITHOUT PROPER TOOLS AND EXTREME CARE!

This is as far as you should need to disassemble the engine, unless you need to
replace a bent crankshaft or front/rear main bearing(s).  If this is the case,
the splined thrust washer will have to be removed before the crank can be with-
drawn.  This is where the puller you alluded to will be needed; the thrust wash-
er is normally press-fit onto a tapered section of the end of the crankshaft and
it gets verrrry tight.  Once removed, the crank can be gently tapped out the 
backplate opening using a plastic or rawhide mallet...TAKE CARE NOT TO BUGGER UP
THE THREADS if the crank is to be reused.  The main bearings can be tapped out 
using an appropriate size brass drift pin and a mallet.  

After required repairs have been made, reverse disassembly steps and reassemble
engine, lubing each component with a light machine oil [gun oil such as Hoppe's
is excellent] and using scribe marks to get everything properly realigned.  If
the engine is ringed and schneurle ported, be aware that there is a tiny pin in
the piston's ring groove which properly locates the ring-gap and prevents the 
ring from rotating; if this is the case on your engine, BE SURE to correctly
align the ring to this locating pin or you're almost guaranteed to break the 
ring when you try to insert the piston into the cylinder-liner [sleeve].

When engine is back in one piece, without glo-plug, carefully rotate crank and
feel/listen for any binding...the engine should bee completely free and smooth.
If not, something's wrong; proceed no further `til the problem's located and 
corrected!!!

Assuming all is well, prepare to run the engine but remember, after being dis-
assembled/reassembled, microscopic wear grooves have been disturbed/misaligned
and the engine should be treated like a new one for a run or two...keep it on 
the rich side for a bit `til things get reseated.  Check tightness of all head
and backplate bolts after each run `til satisfied they're OK; if they should re-
quire tightening, don't overdo it while the engine's hot/warm...if you really
bite them down while hot/warm, the natural expansion of the aluminum castings
can actually pop the heads right off overtightened bolts the next time the en-
gine gets hot.  That's about it...good luck.

> I've also got a new but never used engine that has
> sat in a basement for several years and has surface
> corrosion on the aluminum casing.  How do I clean
> this up.  Should I also take this one apart?
> Should I soak the whole engine in something first
> so that it is easier to get apart?  I'm a little
> worried about stripping the philips screw heads on the 
> cylinder head.

*  It'd be a good idea to have a look inside, checking for interior rust/corro-
sion.  Start by pulling the head and backplate only...if nothing unusual is no-
ted, go no further; reassemble and run.  Soaking the engine in some petroleum 
based solvent prior to disassembly is a good idea.

> Do I have to pull off the prop backing plate and if
> so is this the thing that they sell the pulling tools
> for?

*  Yes.  See disassembly steps above.  This tool can also be handy for pulling 
a stubborn cylinder liner [sleeve].


> Where is a good place to get engine parts cheap and
> quick?  

*  If yer' local shop doesn't stock [or can't/won't order] the needed parts, you
have little choice but to go directly to the manufacturer/distributor or use the
mail-order houses [who will likely be cheaper, even with the shipping charge].

> Also I have an Enya .15 IV.  The glow plug hits the
> piston.  I have a small (old) Enya brochure that says
> it takes standard glow plugs.  I assume this is a "long"
> plug and maybe by standard they mean "short" plugs.
> Or I read once that on some engines you need two washers
> on the plugs.  Do the short plugs have idle bars or it
> it the lack of idle bars that makes them short?

*  Chris has pretty well covered this but, to add my $.02 [for what it's worth],
most plug manufacturers offer plugs in standard [short] or long lengths.  The
difference, as Chris correctly states, is in the length of the threaded portion
of the plug, idle-bar or no idle-bar notwithstanding.

Adios amigo,	Al

I got a replacement needle valve for may '60s vintage Enya .09
directly from Altech Marketing, the importer of the engine.  Call
them first at the number in their ads to get the price of the
part(s).

The Enya .15 uses a short reach glow plug.

Kay, fear not, its not that bad.  I am the biggest chicken in the
world on the subject of engines, and have successfully
disassembled and cleaned several engines from the disused state.
Just this last weekend I cleaned an old TD .049 that I picked up
at the flea market for a quarter, and had it running in about an
hour.  I used rubbing alcohol to clean the parts, and liberal
quantities of WD-40 on reassembly.   

I think Al's note has just about covered the subject; I will add a couple of
observations from my experience. 

I prefer to boil an engine in water over the hot plate to loosen up bearings.
It is possible to overheat the aluminum parts with a gas torch and weaken or in
extreme heat melt the case. 

Using soft jaws on a vice is an effective press for replacing the bearings,
taping with a mallet can cause damage. 

Go to your local bearing supplier for bearings not your model shop, it's a lot
cheaper. You should be able to read the number on the bearing and by quoting
that they will know the size. Failing that take the bearing to the store and
they will match it for you. Don't worry about the "Z" or "ZZ" after the number
as this refers to the dust seal that covers the balls (ie. one side  "Z"; or
two side "ZZ"). If necessary they can be popped out with a small screw driver
to match the original. I run my performance engines without any to improve the
lubrication, it throws a bit of extra oil/fuel out of the front but thats no
big deal. If you want to get better bearings ask for Fanolic (sp) or Fiber
cage, they have reduced friction and don't break up. 

It often helps to soak the engine in Petrol (sorry Gas) for a while. It softens
up the oil residue. 

Don't worry too much about the paper washers. They serve little purpose and
always break when you dismantle the engine. Provided everything is clean during
reassemble you wont know the difference. 

A final word to add to what has been said. Use clean tools in a clean work area
and clean hands throughout the exercise. Wash parts away from the work area,
and store the clean parts in something like a old ice cream container till
ready for reassemble. WD40 spray is a tool to have near by as you can use it to
wash out and lubricate the parts before reassemble. 

John. 

    I DON'T KNOW MUCH ABOUT ENGINES WHICH PROMPTED ME TO BUY THE HARRY
    HINGLEY BOOK ON MINITURE ENGINES. IT COVERS EVERYTHING ON ENGINES
    INCLUDING DISASSEMBLY AND MAINTENCE. 

     In addition to the sunbeam cleaner, which is hard to find in the stores,
     I have very successfully used the spray style brake parts cleaners sold
     in almost all auto parts stores.  This stuff works real good to remove
     all kinds of crud from running but not corrosion.  It also will not harm
     aluminum or steel parts in any way.  Don't get it on paint, plastic or
     rubber as it eats these materials.

     One more thing, it leaves parts absolutely clean when it dries leaving
     no residue!!  I would not use this material indoors and it does tend
     to take the oil out of your skin so BE CAREFUL!!

	ron

						LEO VOSS
						PHYSICAL REPAIR TECHNOLOGY ENG. 
						MAILSTOP: @JGO
 						E-MAIL: NMGV06::VOSS
						DTN: 889-9350

RE: 383.6
    
    Reading this I remember: I have this book. It is quite simple,
    but a lot is covered very clearly. Like how an engine works, how
    to disassemble, run-in etc. And there are nearly 300 pictures 
    just to refer to the text in the book. I wouldn't do everything
    the way Harry described ( especially the pictures showing some
    rework with a handheld drilling machine) but its enlightening
    for the starter.
    
    The book is titled: Harry's Handbook for Miniature Engines
    			by Harry Highley.
    
    There was no ISBN number, but the backside had an adress:
    	Harry B. Highley & Sons, Inc.
    	433 Arquilla Dr. Glenwood  Ill. 60425
    
    Mine was copywrighted in 1980 and I think I bought it in 
    '84 so I am not sure this info isn't outdated. I don't expect but....
    
    Leo
        
   
    

    "Whoa is me" getting everything apart, and the bearings back together
    was the easy part. Now comes that damn prop drive washer. On my OS .40,
    and .46 SF they rely on an interference fit between it and the crank.
    Whats the trick? I tried everything from tapping, to pressing with vise
    to using prop nut with spacer. Everytime the driver washer would cock
    just enough to cause a bur to form on the aluminmun washer and of
    coarse everything comes to a halt. I even tried heating the washer with
    a blow gun with little net gain. I totally ruined one of them, and
    finally got the other on by probably enlarging the hole enough each
    time I cleaned off the bur with an xacto knife after 6 or so attempts.
    It finally went on with a coating of lithium grease and being pressed
    via the prop nut and a spacer. When I buy a new drive washer for the
    other engine I do not want to experiance this again. 
    
    
              WHATS THE TRICK???????? 
    
    
    								Dave
    

    Dave,
    
    Sounds like you've already tried everything that I usually do.  I 
    install a prop, the prop washer and nut, then carefully tighten the nut 
    'til everything's seated.  I normally help things along by coating the 
    shaft with a film of silicone grease but I'd thing almost any kind of 
    lubricant would suffice.  In severe cases I have placed the offending
    part(s) in the oven set at about 200F, leaving them for a half-hour or
    so so they're heated through...this expands the aluminum enough to
    allow a fairly easy fit.  I've never messed with the particular engine
    you mention so there may be a factor I'm unaware of but these methods
    have served me well for many, many years.
						 __
				|      |        / |\	   	       
      	         \|/		|______|__(o/--/  | \	   	       
      | |        00	       <|  ~~~  ____ 04 ---- | --------------------
    |_|_|        (O>o		|\)____/___|\_____|_/	   Adios amigos, Al
      |     \__(O_\_	        |	  |___/	 o	   (The Desert Rat)

    I have two OS 40SF engines, and I have pulled the drive washers off
    of one or both to modify the washers.   I encountered no problems.

After more performance abuse from the Evil One, I took my Webra .61 off my Panic
and replaced it with a 15 year old Super Tigre G.60 that only has a couple of 
break-in tanks through it. I then proceeded to disassemble the Blackhead. Seems 
I had blown my head gasket and my compression is leaking out there. I fixed it 
up and reassembled it to be bench run in the near future. This explains the 
"extra" gunk on my plane that I've been noticing lately.

I'll state it here publicly (again). I'm running these engines because it 
allows me to fly with a minimum of expense. If I had $100+ for a new engine, I 
wouldn't be flying a 5 channel Panic with a 4ch Attack with a "Y" connector.

(I'm also having fun "making do" with what I've got)

And having fun was the purpose!

Jim (the abused)

    Dave,
    	I've had my OS40 apart several times and I have never had any
    problem putting the drive washer back on.  Mine just slides over the
    crank with no help whatsoever.  It is a cone shaped aluminum washer
    that interferes with the drive washer when you tighten the prop nut.  I
    made a special tool to pull the drive washer off out of a piece of 1/16
    steel sheet metal.  It consists of a slot that the drive washer fits
    over (there's a groove for this purpose).  I then tap the end of the
    crank (protected with a piece of brass) with a hammer to pop off the
    drive washer.  It works great and doesn't put any load on the bearings.
    
    Charlie
    

    As John mentioned in 383.5, replacement bearings can be bought in an
    industrial bearing supply store (such as Atlantic Tracy in Nashua).
    To get the correct bearing you will need to tell them the number of the
    old bearing or take the old bearing with you and let them read it from
    the side of the old bearing.  

    The 8/90 issue of RCM mentions another source on page 142.

    	Art Apruzzese                  407-283-6831
    	Revmor Model Products          SASE for a price list 
    	P.O. Box 548
    	Palm City, Florida  34990

    They sell bearing sets according to the make & model of the engine.
    e.g.  front plus rear bearings for an OS FS 61 for $17.55