Today's Message Index:
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1. 05:04 AM - Fuel in oil 912ULS (Peter Thomson)
2. 05:12 AM - Rotax 2 stroke (Catz631@aol.com)
3. 05:54 AM - Re: Rotax 2 stroke (lucien)
Message 1
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| Subject: | Fuel in oil 912ULS |
I have found my oil analyses consistently show 1.2-1.5% fuel in the oil
sample.
Other oil properties (Shell Advance Ultra full synthetic, changed at 50 hrs
on
unleaded gas) are fine. Engine runs quite cool, but no moisture in oil.
Any experiences here ?
Peter
Zenair CH701SP
Rotax 912 ULS 380 hrs since new
OIl analysis by Blackstone
Message 2
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I own a Kitfox with a 912 but some friends of mine bought a Challenger 2
with a Rotax 530 (52 hp I believe) and are flying around in it with little
knowledge of the engine. I am in the same boat as I have concentrated on my 912
and know nothing about two strokes (except I liked the one on my 1962 Saab
96 I used to have)
I went flying in the Challenger the other day and really enjoyed the
flight and the smoothness of the engine. It was the only time I have been in
front of a two stroke. I know they have a dubious reputation if not treated
correctly and was wondering if some of you guys can give me some short tips as
to the proper care and feeding of the engine which I could pass on. As an
example, when the pilot I was flying with pulled the power back on descent, the
EGT red warning light came on warning of exceeding the red line (or close)
The pilot blew that off as a fault, but I am not so sure.
They plan on going to school on the two stroke (Lockwood,Mississippi Light
Aircraft,etc.) but in the mean time, is there anything to watch out for.
The engine has about 325 hrs on it .It was torn down and checked prior to
purchase and was reported very clean. It runs and starts great! The outside temp
this time of year is running close to 100 degrees (it sucks !!!!) You have
to put a block of ice on the engines to cool them down for start!
I have a CPS catalog which has super info on the two strokes and will give
that to them but I thought perhaps some tips from guys with real real
experience would be useful until they get to school.
Thanks !!
Dick Maddux
Kitfox 4
Rotax 912 UL
Milton,Fl
**************Make your summer sizzle with fast and easy recipes for the
grill. (http://food.aol.com/grilling?ncid=emlcntusfood00000005)
Message 3
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| Subject: | Re: Rotax 2 stroke |
Dick Maddux wrote:
> I own a Kitfox with a 912 but some friends of mine bought a Challenger 2 with
a Rotax 530 (52 hp I believe) and are flying around in it with little knowledge
of the engine. I am in the same boat as I have concentrated on my 912 and know
nothing about two strokes (except I liked the one on my 1962 Saab 96 I used
to have)
> I went flying in the Challenger the other day and really enjoyed the flight
and the smoothness of the engine. It was the only time I have been in front of
a two stroke. I know they have a dubious reputation if not treated correctly
and was wondering if some of you guys can give me some short tips as to the proper
care and feeding of the engine which I could pass on. As an example, when
the pilot I was flying with pulled the power back on descent, the EGT red warning
light came on warning of exceeding the red line (or close) The pilot blew
that off as a fault, but I am not so sure.
> They plan on going to school on the two stroke (Lockwood,Mississippi Light
Aircraft,etc.) but in the mean time, is there anything to watch out for. The engine
has about 325 hrs on it .It was torn down and checked prior to purchase
and was reported very clean. It runs and starts great! The outside temp this time
of year is running close to 100 degrees (it sucks !!!!) You have to put a
block of ice on the engines to cool them down for start!
> I have a CPS catalog which has super info on the two strokes and will give
that to them but I thought perhaps some tips from guys with real real experience
would be useful until they get to school.
> Thanks !!
> Dick Maddux
> Kitfox 4
> Rotax 912 UL
> Milton,Fl
> Make your summer sizzle with fast and easy recipes (http://food.aol.com/grilling?ncid=emlcntusfood00000005) for the grill.
>
Well, you already discovered one of the main operational differences between a
2 and a 4 stroke on that flight ;)
Namely, a high rpm/closed throttle situation like you commonly have in a descent.
This is no problem on a 4-stroke of course and in fact is even kind of good
for it, but it's very hard on a 2-stroke. The difficulty being that there's a
lack of fuel/oil mixture going through the spinning engine to lubricate it when
the throttle is closed and the engine is being windmilled by the prop.
Tips to avoid this situation:
- when descending pull all the way back to idle and descend at lower speeds, i.e.
with a max-effort slip or circling, etc. Anything to avoid windmilling the
engine with the throttle at reduced or closed settings.
- if you have a C box, fit the rk400 clutch. This offers a complete cure as it
disengages the engine from the gearbox completely at idle. Just pull the engine
back to idle and you can dive at Vne if you want with no problems.
Not an option on the challenger tho.
Some other operator errors I see with the 2-stroke:
- shock heating, in the form of going immediately to wide open on a cold engine
either from not doing an adequate warmup or after a long descent that cools the
engine down. A 4-stroke is a fair bit more forgiving of this even tho it's
not great practice there either, but the 2-strokes (especially the water cooled
like the 582) are not. You can get away with this for a while on the air-cooled,
but eventually this will put you down somewhere. On throttle-up, you need
to be smooth and gradual if the engine is cool. A good warmup on the ground before
takeoff is essential.
- running them too hard. You can't run a 2-stroke like we can run our 912's and
other 4-strokes. Those we can basically run as hard as we want for as long as
we want long as we don't overspeed them, they'll just laugh at you. You can't
do this with a 2-stroke - even the 503 will eventually give up the ghost if run
at too high of a throttle setting or too high of an rpm on a continuous basis.
- tweaking and tuning the jetting for the ragged edge of power output. Don't do
this - follow the rotax jetting chart to the letter as field experience has shown
this to be correct. You need to run rich on the top end, for example, to
keep things cool and well lubricated at full power settings.
- underpropping or underpowering. Underpropping leads to an overly lean condition
which is a disaster waiting to happen. Underpowering forces you to run too
hard (i.e. if you need more than 5800 all the time just to stay in the air, you
need a bigger motor or a better prop.
That's most things I can think of off the top of my head. Generally good training
is the best medicine on this and it's not too big of a burden on having a good
time with a 2-stroke. They'll last a long time and give good service long
as you follow the basic guidelines....
LS
--------
LS
Titan II SS
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