Rotax 447 break-in

[brian johnson]

I finaly did my break in on my total rebuilt 447 (point). This was the
first time with this engine, 2.58/1 box, ground adjustable prop, on this
plane. Tractor configuration. I found her very hard to keep at a steady
RPM at certain times. Running the break in at the 5 minutes for 5500RPM
would tend to jump between 4000 and 6000 at times. It this normal? It was
not an extreem jump but rather started to slowly drop or rise and the
correction may have helped the increase and decrease somewhat. Also I was
confused with the "full" RPM runs. I increased my RPM to full and she would
rise up to the 8000 RPM area so I only ran the full setting at 7000 or
slightly under. The rear CHT would also rise to 500 so I cut it a little
short so not to loose the one engine I have. EGT was great at 1250 or under.
This is a free air cooled engine too.
Whatcha think. I'm too green to figure all this suff out with out the help
of you vets..... Thanks guys. Launchpad
PS. The carbclip is on the second notch and is in the correct position.
(Bing)

[Scrappman]

Prop it down to 6200,,, 6000 static, full throt. gGo from there. !250 is a
bit high. the old man. said not to run the motor at 7/8 for any length of time,,
tends to run a little lean.
Scrappman
Was the prop powerfin.... ivo,,gsc.?

[ls]

Sounds like the motor is underpropped. You should turn about 6200 rpm or
thereabouts at full throttle. The vascillating rpm at the mid throttle
settings is probably due to being underpropped, but it could also be caused
by simply being too lean at that setting (or both).

This isn't normal procedure, but I usually use a size larger main jet than
the recommended one during the ground breakin just for insurance purposes.
This way the motor is a tad rich during the full throttle portions, allowing
a little extra lubrication and cooling (usually the plane is tied to a tree
on the ground during this initial breakin and there's less cooling airflow
as a result). That's the only change I make, I leave the jet needle and idle
jets set as recommended in the manual.

1250 is probably borderline hot on the EGT, but if you're turning 8000 rpm,
that's probably not an abnormal reading. 500 deg on the CHT is pretty scary
though.....

So, I'd get the proper prop load on the motor first and then go from
there....

LS
AC fun racer.

"brian johnson" <weedh...@usol.com> wrote in message
news:ti76pr5...@corp.supernews.com...

[UltralightNews]

You might want to check out:
http://www.ultralightnews.com/enginemaintenance/maintenance/gauge.html

I am surprised your engine didn't seize up on you during break in.

"brian johnson" <weedh...@usol.com> wrote in message
news:ti76pr5...@corp.supernews.com...

[brian johnson]

Thanks much. I will adjust the prop tomorrow morning. It is a Precission
Prop (2 blade). As for the EGT at 1250.. It was only at that when I was
at full RPM and even then it was more like 1225 or so. It was around 1100
to 1200 at all other higher settings.. The CHT was at 500 only above
5800RPM and the rest of the time 390 to 425. The one thing I did not
mention was that when I gave it throttle from the idle (2000) it would drop
RMP for a sec around the 3500 range. I figured this was a simple tuning of
the carb though. Once change the prop then I will see what change I have.
I bet money you guys are totaly right. Til tomorrow.....Launchpad