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grantr
Joined: 12 Sep 2007
Posts: 217
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 Posted: Tue Sep 30, 2008 4:55 am Post subject: EGTs are reading too high on 503 1200o |
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Prior to the EGT problem, I installed new fuel lines, fuel filter, electric fuel pump, Westach dual EGT gauge, One new egt probe, cleaned and reoiled the k&N filter and rebuilt the pulse pump.
The plane was originally setup with 1 CHT/ EGT westach gauge. I am still using the CHT side and disconnected the EGT side and plugged it into the new dual EGT gauge.
CHT is still running the same
Both EGTs are running 1200 degrees from over 4.5K to max rpm. The EGTs held steady even at full power climb.
I know before the work I did, the PTO cylinder was running in the 900s as indicated on the single EGT gauge. The original EGT gauge wiring used a telephone cord which uses longer and thinner wire than the 26 gauge wire I used to connect the new gauge. So my new wiring is as short as possible and uses a little bit larger diameter wire.
Is there a way to calibrate the gauge so it is accurate? Should the ends connected to the EGT gauge have a certain resistant at normal outside temperature?
Also what is the proper way to check the spark plugs? I checked the set that’s been in for 25hrs and they are very light brown. I saw somewhere that the engine should be shutdown at ¾ throttle to get an accurate reading on the plugs. That doesn’t sound like the best thing to do to the engine.
Grant
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JetPilot
Joined: 10 Jan 2006
Posts: 1246
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| Posted: Tue Sep 30, 2008 5:25 am Post subject: Re: EGTs are reading too high on 503 1200o |
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What you heard about shutting down the engine at higher throttle to get a reading on the plugs is correct, I would not make a habit of it, but it wont hurt a small 2 stroke to shut it down like that once in a while to read the plugs. Make sure the engine has cooled down very well before you put the plugs back in, aluminum gets soft at high temperatures, and torquing into hot aluminum is a perfect way to strip the Threads out.
An EGT of 1200 is a bit higher than you want, I would work to bring that down a bit. Pitching your prop more ( For less RPM ) is very effective at bringing EGT's down. You could also try a larger size jet... What worked best for me was to use stock jets and needle settings, and pitch the prop a bit more to put the EGT's exactly where I wanted them. The engine ran perfect throughout the range using this method. Moving the needle caused a much to large change in EGT's on my engine, it went from slightly hot to way to cold. Changing the main jets worked better, changed EGT's just a littile, but it also caused rough running at some RPM's.
Mike
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grantr
Joined: 12 Sep 2007
Posts: 217
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| Posted: Tue Sep 30, 2008 5:49 am Post subject: Re: EGTs are reading too high on 503 1200o |
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Mike,
In general how long would I need to run the engine at say 3/4 throttle to get a good reading on the plugs? 5 minutes or so?
I have a IVO prop so it is easy to adjust.
Grant
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jbhart(at)onlyinternet.ne
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| Posted: Tue Sep 30, 2008 6:03 am Post subject: EGTs are reading too high on 503 1200o |
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At 06:25 AM 9/30/08 -0700, you wrote:
| Quote: |
Moving the needle caused a much to large change in EGT's on my engine, it
went from slightly hot to way to cold. Changing the main jets worked
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better, changed EGT's just a littile, but it also caused rough running at
some RPM's.
Mike,
This is why shims are useful.
See:
http://www.thirdshift.com/jack/firefly/firefly58.html
Fly safe!
Jack B. Hart FF004
Winchester, IN
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grantr
Joined: 12 Sep 2007
Posts: 217
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| Posted: Tue Sep 30, 2008 2:52 pm Post subject: Re: EGTs are reading too high on 503 1200o |
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no one knows how to calibrate the gauge?
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grantr
Joined: 12 Sep 2007
Posts: 217
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grantr
Joined: 12 Sep 2007
Posts: 217
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| Posted: Sat Oct 04, 2008 6:25 pm Post subject: Re: EGTs are reading too high on 503 1200o |
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I ran a series of test and i think the EGTs may be in fact a tad high. I am going to shim the carb needle clips to enrich the mixture a tad and see if that helps.
Thanks Jack for the information on your website http://www.thirdshift.com/jack/firefly/firefly58.html
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Blumax008(at)aol.com
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| Posted: Sat Oct 04, 2008 10:53 pm Post subject: EGTs are reading too high on 503 1200o |
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Grant...
This is Bill Catalina. I used to post quite a bit on here but finally got tired of the BS that goes on in this site.
Look, I've been flying 2-cycle motors on ultralights since the mid-70s. The 503 is without a doubt, the toughest, most durable, most trouble-free, bullet-proof 2-cycle motor on the market. I have had 3 (on 3 separate U/Ls) in the past ten years & will never again go thru the hassles of owning a 582 with it's hoses, anti-freeze, radiators, oil tanks etc.
The 503 on my Trike just celebrated it's 10th. anniversary with over 1,600 hours with only 3 top overhauls. The Crankshaft has never been touched. Most of that time is running full throttle towing hang gliders. That's TEN YEARS of steady, high speed, mostly flat out running. It also runs cooler the harder you run it.
Take it up one day soon & do this...from your normal cruise rpm, floor it to full power & hold it steady at full power (don't worry, it won't break) & watch your EGT. You should see an almost immediate DROP in EGT temp.
If your EGT's are showing a "tad" lean or even a "tad" rich...don't fix it. It's fine. It will not break.
I will leave you with my most often repeated advice...
IF IT AIN'T BROKE...DON'T FIX IT.
I don't respond to any replies as they're usually below my intelligence level & usually spoken by people who spend too much time on this website & not enough time flying.
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