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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
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 Posted: Tue Jul 17, 2007 10:36 am Post subject: FS 1 First Flight questions |
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| If you do not have a primer, sell your EGT gauge and get one.
Just
| kidding ,,,,,,, but do get one.
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| These EGT gauges are notoriously inaccurate.
|
| Gene Z
Gene:
You can get the same results, in flight, with the enricher. Not only
on the two strokes, but it also works on the 912 series engines.
Old fashioned, using the enricher on all my engines.
john h
mkIII
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_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama |
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Thom Riddle
Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)
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| Posted: Tue Jul 17, 2007 12:26 pm Post subject: Re: FS 1 First Flight questions |
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My my! What great responses this question has triggered. Keep them coming. Meanwhile, I'll tell you what I did this morning and the results.
1) I removed the spark plugs to see what story they would tell. They both looked a bit lean, not terribly so, but definitely lighter than the tan/light brown that I like to see. They were grayish white. This tells me that the engine was indeed running a bit leaner than it should. The gaps were in range and the plugs not worn much. However, the gaskets that come on the plugs were in place and should not be when using spark plug ring type CHT thermocouples, so I cut them off and applied anit-seize to the threads and reinstalled, and torqued them to spec.
2) I opened up the top of the carburetor and removed the contents. The clip was in the #3 groove, not the #2 groove as per Rotax recommendations. The clip and o-ring were below the white cup as it should be. If everything else in the carb is correct, then in #3 position, it should be running a bit on the rich side of optimum. I checked the jet needle number and it was correct. I did not go deeper into the carb but will on another day to see if the needle jet is the proper one and all other parts as well. I suspect the needle jet is the wrong number. I lowered the clip to the #4 groove (lowest/richest) and put all back together and took it for a spin.
RESULTS:
No appreciable change in EGTs or CHTs during WOT CLIMB... still in normal range. The EGTs in cruise rpm range were about 100 rpm lower than before moving the clip down to the last groove. Still higher than normal range but less than the MAX allowable temp. The CHTs did not change noticeably. The engine felt like it had more power and this was confirmed when I went to WOT in level flight. The max rpm is now 6,600 rpm where before it was 6,500 rpm. This confirms that the engine was running lean of peak power, at least at WOT.
Next Steps:
a. Increase pitch in prop to get 6,500 rpm at WOT level flight.
b. Take carb apart and clean/inspect/check for proper jets etc.
I'll post results of these steps as soon as possible but it will probably be a week before I get to do it. At least now, I can fly without fear that the EGTs are running too high in cruise.
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Thom Riddle
Buffalo, NY (9G0)
Don't worry about old age... it doesn't last very long.
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Eugene Zimmerman
Joined: 10 Jan 2006
Posts: 392
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| Posted: Tue Jul 17, 2007 5:23 pm Post subject: FS 1 First Flight questions |
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Hey John,
I believe your $.02 on the subject will probably buy as much as
mine,  except perhaps at higher power settings.
The enricher becomes decreasingly effective as the throttle is opened.
In fact one reason some people have difficulty starting a cold engine
using the enricher is because they open the throttle too far for the
enricher to be effective. The enricher works different than a choke.
I know I'm preaching to the choir with you.
Gene,
On Jul 17, 2007, at 2:36 PM, John Hauck wrote:
| Quote: |
| If you do not have a primer, sell your EGT gauge and get one.
Just
| kidding ,,,,,,, but do get one.
|
| These EGT gauges are notoriously inaccurate.
|
| Gene Z
Gene:
You can get the same results, in flight, with the enricher. Not only
on the two strokes, but it also works on the 912 series engines.
Old fashioned, using the enricher on all my engines.
john h
mkIII
|
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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
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| Posted: Tue Jul 17, 2007 5:52 pm Post subject: FS 1 First Flight questions |
|
|
| I believe your $.02 on the subject will probably buy as much as
| mine, except perhaps at higher power settings.
| The enricher becomes decreasingly effective as the throttle is
opened.
|
| In fact one reason some people have difficulty starting a cold
engine
| using the enricher is because they open the throttle too far for the
| enricher to be effective. The enricher works different than a
choke.
| I know I'm preaching to the choir with you.
|
| Gene,
Gene:
Reason I shared my little bit of info is because it worked with me and
the 912UL.
Did not feel like it was running as crisp as it should at 5,000 rpm
cruise. Had had a problem with this same engine on my flight to
Deadhorse, AK, in 1994. Was still working on the problem with less
than ideal performance at cruise in colder climates. After I got back
home, I experimented a lot trying to come up with a fix. While on a
cross country flight to Mobile, AL, I got the idea to pull on the
enricher. When I did, cruise speed increased 200 rpm. When I got
back home, I pulled the carb piston, raised the needles a knotch, and
my cold weather and warm weather midrange problem was solved. Wish I
could have figured that out in Alaska. I would have made Point Barrow
in 1994 instead of 2001.
BTW: After I raised the needles in the 912, I checked the enricher at
cruise rpm and the engine lost 200 rpm, indicating the enricher was
making it go over rich. I might add, the 912 is tuned very close to
max lean in midrange. Does not take much more leaning to piss off the
912 and make it act up. Definitely gets the pilots attention.
I realize the enricher is not a choke. That is why I never had a need
for primers. Never had a problem starting pull start, electric
starter two strokes, and four strokes, using the correct procedure for
starting. Do it right by the book and it works for me.
john h
mkIII
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_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama |
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