Model Forum / Radio Controlled / Air Models / July 2008

It will be hard to turn over but not very hard.  It should not run hot,
check the head screws and back plate screws.  When they are new they are
hard to turn over.  Make sure you don't run it lean, or very rich.
mk

.

Try adding about 4 ounces per gallon of racing castor oil.  The extra lube
is good for it, and if you are using all synthetic fuel, it will help
prevent rust, and promote cooler running.

It does make a more dirty engine, and harder to clean, but to me, the
protection is worth it.

I hope you did not harm the engine with it's first running, but it is
possible that you scoured the piston and cylinder.  You might need to take a
scotchbrite pad to the parts, or some very very fine emery cloth to it, as a
last resort.

Did you buy this engine new or used ?

Without actually seeing what is happening , my guess is that you're
running it TOO rich. That's an ABN engine ( aluminum ,brass nickel)
with a tapered liner. If the engine doesn't get hot enough to
expand the liner at the top , then there is not enough clearance and
the piston 'drags' at the top. Can you feel the drag at the top when
you turn the engine over cold ? That will tell you that something has
to happen to free that engine up so it will run like it should , and
that something is heat.

All ABC , ABN and similiar engines will be very stiff at the top ,
sometimes almost to the point they feel 'locked up'

You can ......RUIN....... an ABN or ABC type engine by running too
rich. The first few minutes are the most critical.
It's got to expand enough enough at the top to allow the piston to
pass through that tight spot. If it doesn't get hot enough to expand,
then the piston is forced through the tight spot and will wear
it excessively. This also puts undue stess on the crank pin and could
possibly bend or break a con rod. Then the engine heats , when the
engine is too hot it also changes the timing , it will fire sooner and
further add to the heat problem.  

With all this drag going on you can see why the engine will run hot
even sloppy rich.
Of course , you should always feel a little pinch at the top when the
engines cold , just shouldn't feel like it's locked up.  

Also , make sure you're running the correct prop for that engine.
Actually , a smaller prop is better during break in. That allows the
engine to turn up better and and also remain cool.
Just go down 1" in diameter or pitch and that will be fine.
I think that engine in most aps will run a 11x6 , so a 10x6
or 11x5 will be fine for break in.
High RPM is very important to the break so we don't want
too much of a prop load on it.

I'm sure that someone will be correcting me , but here is how I've
been doing it for the last 20 years or so.
I'm not saying this is the only way , but it definately works.

Using the smaller prop , start the engine and go to a real fast idle.
Let it run like this for a few seconds until you see that all is okay
with the engine , such as a knocking , something loose or any other
strange sounds. Now advance to half throttle and make sure it's
a little on the rich side before we go full throttle. After 30 seconds
or so goto full throttle and lean the engine to it's max rpm , then
.....immediately..... back off a couple clicks. One wayto test to see
if you're at the proper needle setting is to pinch the fuel line for
about a half second or so. If the engine speeds up then you're pretty
much on the money. If it sags, it's too lean. We want the engine to
get hot but not overly so.

I always reach over and feel the head with my finger to check
the temp , I sorta slide my finger over the head or the  side of
the crankcase. You should be able to make contact for a second
or two.
At this point in the break in it will heat pretty quick so stay with
it.
When it gets too hot to maintain contact , richen it a few clicks and
the head wiil cool quickly. Do the touch test , after cooling , go
back to the lean full throttle setting.s....two or maybe three clicks
from maximum RPM.
Do the fuel line pinch thing.

You can also use an Infrared thermometer to keep track of the temp ,
but I like this way better.

Do this through at least two tanks of fuel. Most engines will be
broken in enough to fly by then.

As I mentioned earlier , you will see the engine running cooler and
cooler at the same needle setting.

Another plus to breaking in this way.....your engine will turn more
RPM's and perform better than engines that aren't broken in
correctly.

After this , I would put the 11x6 on it and go flying.
But be sure you don't run too rich......or lean.

I hope this helps. Let us know how it goes.

Ken

All engines run hot (to touch). TT's PRO 46 ordinarily runs just like
any O.S. engine, and many would argue "even better".

It sounds like you haven't got enough oil in your fuel, probably too
much nitro and possibly too hot a plug.

Stick it on the bench. Fit a Bolly 10.5x5 or APC 10x6, use a fresh
container of fuel containing no more than 5% nitromethane, a minimum
of 18% oil which for initial running in (first half dozen tankfuls) is
preferably all degummed castor, fit an O.S. #8 or equivalent heat
range quality plug (eg: Enya #4), open the needle valve 3½ to 4 turns,
prime (4-6 choked rotations with throttle open wide) and start. Remove
the ni-starter and close the needle valve until the engine just breaks
into a (rich) two stroke. Run for 5-10 minutes, leaning out testing
and adjusting idle mixture for smooth transition as required. When
it'll hold a constant two strokem idle and transition smoothly, shut
down, stick it in your plane and fly. IME, TT's will usually do this
OOTB. If I stick them on the bench at all, it's just to give them an
initial run to set up the N/V and adjust idle/transition, sort out any
problem (never does with TT) should one appear before putting it in a
model. I have 4X TT PRO 46s. The word "runs like a Swiss watch"
cliche' comes to mind. Pure platinum.

Hi Solo.
Sorry for you,but If I'm right your problem will be back soon.
experienced the same situation whole summer with my pro46. No one at m
club could explain it. Next time it hapens, have a close look at you
glow plug. You will notice small "iron balls" welded to glow pug'
element. These are small parts of metal coming from the rear cran
shaft ball bearing. The "fused" metal parts are also what is keepin
the piston out of TDC. The bearing is a NTN6902 and was rusted , s
that the spacers between the balls(bearing) was falling apart.
My engine is 2 years old (2 gallons burned)
Burned 6 glow plugs to figure this out.$$$$
bearing is 20$ at bearing dealer
Take good care when removing that bearing, it's not easy!
From now, I'll be using "after run oil" and also added oil in m
gallon.
Let me know if I'm right

--
ve2ao

Problem is solved. found replacement bearing for 3$ in another bearin
shop. Engine runs like new for 3$

--
ve2ao

Re Thunder tiger pro 46. I recently installed a new tt pro 46 in a
older sport plane and I installed the prop and it test turned smoothl
as would be expected.
I then fitted the muffler and gasket using the screws provided an
found that the engine locked up at top dead centre. I backed off th
exhaust screws and it freed up the piston again. I have since run i
this engine on the bench with the exhaust screws only lightly nipped u
and i have slowly tightened the screws
to the correct tension and now after approx 3 hours of slightly ric
flights all is well.
This is my experience and it may be worth checking that there is not
distortion caused by the muffler bolt tension when your engine is warme
up

--
stevej5