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What do you think?

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Posted

Quote from TKF:

 

Hi guys, 

I've recently acquired a Kitfox 4 and I cant get in the air any long than about 30mins without something going wrong. (makes it quite hard to get my tail wheel endorsement when I cant stay in the air long enough) Its a Rotax 582 Grey Head, approx. 350 hours and 15 years old... never been rebuilt.

Also keep in mind I'm in the northern end of Australia and our flying conditions here are very humid and hot (38°C) 400ft MSL (3000ft Density Alt)

1. First flight : the engine would start to drop RPM (500-1000) for no apparent reason at high RPM. Especially after about 15 secs of WOT. High EGT and high Water Temps. I figured it was a fuel issue, cleaned out all the tanks and fuel, changed the coolant to more water based mix and dropped the radiator 3" into the air stream. I also richened up the mixture one clip on the needle.


2. Second flight : This time I had good EGT temps, Coolant Temps are fantastic... but once again... on a go around at WOT... engine uncommanded drop of 500-1000 RPM only for a short time though. This time I think it might be the fuel pump, so I replaced the gaskets, I also worked out my needle setting should be back on the leaner side due to the higher Density altitude (and slightly dark plugs) and put it back to 1 clip leaner setting and also changed the main jet to one size smaller (leaner). I've also pulled the heads off and noticed my pistons are covered in big flaky bits of crud and the rings are stuck. So, I cleaned it and reassemble.

3. Third flight : I work out I shouldn't be taking off with the flaps in the spoiler position, the aircraft leaps into the air and everything is running great and I'm starting to have hope. There is also a noticeable increase in performance, yes it was doing 70kts!!!!. 

After about 10 minutes of circling an abandoned airfield the engine starts to (or at least what I think it doing) misfire! Randomly every 1 or 2 seconds you can feel a kick/thud through the airframe, no drop in RPM. My instructor took over and we headed back to the airfield and by the time we had landed it had gone away.

I'm at wits end with this engine... my instructor won't get back in it with me until I get a new engine. Why would it be misfiring? Should I keep trying to extend the life of this thing, or just bin it?

Help.

 

 

Sounds like the motor is used up to me.  Seals probably dried out and in need of a rebuild.  Thoughts and comments welcome from the oil burners out there….

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Posted

15 years old and only 350 hrs in a hot humid climate......hmmmm guy needs to start over from scratch. Sounds like he's a little too excited to just monkey with random things too. I wouldn't think of flying again after losing 1000 rpm without having any idea why.

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Posted

I think with the age on the engine, new seals and a complete inspection are in order.  I had a 582 that had quit on the guy before I got it.  Seemed to run okey afterwords.  When I tore it down you could see the scuffs on the pistons but couldn't see them before it was tore down.  I had to get it bored out to the next size.  The guy mentions that the rings were stuck and he had the heads off.  Did he actually pull the cylinders and do a proper decarbon job?  After he gets the engine gone through, then make sure the filters and carbs are clean .  Stock needle jet and jet needle set maybe 1 step leaner than stock setting, and probably 162 main jets to start with.  CPS has a chart in their catalog that says what settings should be at different altitudes.  Just my 2 cents, after flying behind at least

a dozen different two strokes, half of them at least my own.  Jim Chuk

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Posted

Are the little plastic screens in the carbs installed. that is if you have Bing carbs What they do is stop fuel from bubbling which sounds exactly like what you have. Also set the plane at a high angle of attack and do a fuel flow test. Its a two stroke, if it has air and fuel it will run. Just have to figure out what the problem is.

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Posted

TJay this thread is a year old and from another forum but thanks for the reply. This was another classic case of someone having NO clue about two strokes or how they work trying to operate one. I wonder what the outcome ever was? Probably never learned to fly and tells as many people as possible how bad two strokes are.

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Posted

lol oh yeah its 2015, and only January yet, oh well

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Posted

I know his thread is old, but for anybody else flying behind a two stroke, the thumping you feel in the airframe or rudder pedals means your mixture is to rich. Try leaning it out one clip. I richen my mixture until I feel that thumping then give the mixture control one turn to the lean side. That should make it real close to the right mixture.

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Posted

Bandit, do you have an Arctic Sparrow or a HAC mixture adjustment.  I have an Arctic Sparrow.  I don't often need to adjust it.  When the outside temperature gets warm I get the thump in the rudder pedals.  One turn in the lean direction stops it.  I had the thump on my first test flight and thought there was someone back there hitting the trailing edge of the rudder with a hammer every few seconds.  it took me a couple flights to figure it out.

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Posted

yes I have the Arctic sparrow mixture control when I get the knocking that is exactly what I do also

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Posted (edited)

Just in case some of you don't know about the maker of the Artic Sparrow mixture control - Mike Jacober was a friend of mine at Birchwood Airport, Alaska - and I'm sure that Leni and Suberavid know a lot more about him than I do.  He set some altitude records in Alaska before he was killed in a crash.

EDMO

Edited by Ed In Missouri

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