Today's Message Index:
----------------------
1. 12:02 AM - Re: Engine Stumble on Climb Out (Looigi)
2. 01:24 AM - Re: Engine Stumble on Climb Out (Richard Goode)
3. 03:23 PM - Re: Chinese rebuild engine (Flibob)
4. 06:07 PM - Re: Re: Chinese rebuild engine (Anthony Savarese)
5. 06:37 PM - Re: Re: Chinese rebuild engine (Bob Graves)
6. 06:56 PM - Re: Re: Chinese rebuild engine (Walter Lannon)
7. 07:26 PM - Re: Re: Chinese rebuild engine (A. Dennis Savarese)
8. 07:28 PM - Re: Re: Chinese rebuild engine (Walter Lannon)
Message 1
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| Subject: | Re: Engine Stumble on Climb Out |
Hi there,
We had exactly the same fault on ours a few months ago. I found that one of our
magneto coils had an intermittent open circuit.
Have a measure of the resistance through the electrode of your spark plugs. I
will be that at least one of them will have a high resistance. They should measure
1000-1500 ohms.
I will be happy to skype and chat through my findings if that helps you out.
Regards
Chris
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480531#480531
Message 2
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| Subject: | Engine Stumble on Climb Out |
This is a classic symptom of coil failure - we have seen it on over 30
different aircraft over the years! Typically it is always heat -related.
That is, with a cold engine, it will run perfectly with normal small
magneto-drop. But when the engine warms up (normally 20/30 minutes after
take-off), and heat soaks through to the magneto, the coil begins to break
down. The problem is exacerbated because of the design of the coil in which
the condenser (and it seems to be the condenser that fails) is inside the
coil, and so the heat from the wire coil warms the condenser that much more
than the temperature of the inside of the magneto.
We have spent a lot of time researching the issue, and now make coils with
the condenser bonded externally to the coil, but it is relatively small and
does not affect mounting the coil. Also, with the external condenser, we are
finding that the magnetos give a stronger spark from very low rpm.
Finally, it is worth saying that we test every magneto and indeed each coil
in a high-temperature test cell for a minimum of two hours where the magneto
is heated to a higher temperature than it would ever encounter during
flight, the obvious aim being to check that the magneto/oil not going to
fail in service.
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
Tel: +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com
-----Original Message-----
From: owner-yak-list-server@matronics.com
[mailto:owner-yak-list-server@matronics.com] On Behalf Of ggtyler
Sent: 31 May 2018 07:45
Subject: Yak-List: Engine Stumble on Climb Out
Just a bit of excitement in the Yak 52TW today.
Flight before last the engine did a hard stumble twice in succession on
climb out. I immediately swung back towards the field, but once I pulled
back from 2400RPM to 2100, it smoothed out. Gave it a few minutes, played
with the throttle and rpm's and it did not come back. Figured it was just a
fouled plug.
I did a couple more hours of flying and starts/stops that day with no
issues.
Went up again today, and on climb out, 2400 RPM, hard stumble. Then another,
and another, quickly turned back, pulled back to 2100 RPM, but the hard
stumbles proceeded to keep happening. At one point, I was pretty sure it was
going to quit running entirely. That 1.5 seconds or 2 seconds of stumbles in
a row can feel like an eternity.
It was running pretty badly, wife was in the back on her second flight ever
with me. I was pretty darn stressed, so more focused on getting back on the
ground safely than anything else. I did not think to do a mag check, but
didn't really have time, as I had only just made pattern altitude by the
time I was on downwind. I did scan through all the instruments, and all
temps/pressures seemed be normal.
On final, I must say, I just wanted us to be back on the ground NOW, and was
getting in a bit of a hurry to get down. Realizing that stress was dictating
my landing, I just kept telling myself "don't get in a hurry, hold it off,
hold it off". Not my best landing ever, but not one I need to be ashamed of.
I did find it hard to keep my legs from bouncing all over while taxing. Not
often I get that much adrenaline pumping.
Wife's a bit of a gear-head so knew everything was definitely not cool, but
she stayed calm and didn't freak out. It's nice to have someone to hug after
a bit of a scare.
Dropped a text to Vladimir Yastremski (he does my annuals). That guy always
calls me back, no matter what time of day. He's even on vacation right now.
Talk about service! Diagnostics will come later, and will update here.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480530#480530
Message 3
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| Subject: | Re: Chinese rebuild engine |
Still working on this engine. Starts but won't run unless 1. Throttle is pumped
constantly or 2 wobble is pumped or 3 primer is pumped. Any of which will keep
engine running at 1500 +_.
I have taken the carberater and fuel pump off running engine with no effect. Also
cleaned points in both mags.
Any ideas?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480534#480534
Message 4
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| Subject: | Re: Chinese rebuild engine |
Serious look into the mags. Check to make sure points are clean and dry. CJ point
gap, .010-.014. Check timing. Note what number is stamped in the cover mating
surface and correlate that number to timing chart. Once timing has been checked,
then check the rotor leading finger in the counterclockwise rotation position
alignment to the scribed mark on the cover mating surface. It close to the
HV stick.
Dennis
Sent from my iPhone
> On May 31, 2018, at 6:22 PM, Flibob <Flibob@att.net> wrote:
>
>
> Still working on this engine. Starts but won't run unless 1. Throttle is pumped
constantly or 2 wobble is pumped or 3 primer is pumped. Any of which will
keep engine running at 1500 +_.
>
> I have taken the carberater and fuel pump off running engine with no effect.
Also cleaned points in both mags.
>
> Any ideas?
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=480534#480534
>
>
>
>
>
>
>
>
>
Message 5
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| Subject: | Re: Chinese rebuild engine |
Thanks Dennis
GiddyUp,
Bob
On May 31, 2018, at 9:07 PM, Anthony Savarese <dsavarese0812@bellsouth.net> wrote:
Serious look into the mags. Check to make sure points are clean and dry. CJ point
gap, .010-.014. Check timing. Note what number is stamped in the cover mating
surface and correlate that number to timing chart. Once timing has been checked,
then check the rotor leading finger in the counterclockwise rotation position
alignment to the scribed mark on the cover mating surface. It close to the
HV stick.
Dennis
Sent from my iPhone
> On May 31, 2018, at 6:22 PM, Flibob <Flibob@att.net> wrote:
>
>
> Still working on this engine. Starts but won't run unless 1. Throttle is pumped
constantly or 2 wobble is pumped or 3 primer is pumped. Any of which will
keep engine running at 1500 +_.
>
> I have taken the carberater and fuel pump off running engine with no effect.
Also cleaned points in both mags.
>
> Any ideas?
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=480534#480534
>
>
>
>
>
>
>
>
>
Message 6
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| Subject: | Re: Chinese rebuild engine |
The engine was most likely overhauled about 30 years ago. The inhibiting
oil, in normal circumstances for a military operation, would be cleaned out
and re-applied in an absolute maximum of 6 years. It is "running" on the
start solenoid and the primer NOT the carburettor.
You must follow the de-inhibiting process in the manual TO THE LETTER and
beyond since the oil has long since turned to hard grease. Particularly
true for the carburettor but applies to everthing they list in the manual.
Once you get serious and spend a few days on due diligence it will start and
run like a top. Do not mess with the point gap setting. The factory will
have set these
at exactly 0.3 mm (0.012"). Just make sure they are perfectly clean
Of course you have already confirmed that the carburetor ambient air tube in
the carb. throat is not blocked.
Cheers;
Walt
-----Original Message-----
From: Flibob
Sent: Thursday, May 31, 2018 3:22 PM
Subject: Yak-List: Re: Chinese rebuild engine
Still working on this engine. Starts but won't run unless 1. Throttle is
pumped constantly or 2 wobble is pumped or 3 primer is pumped. Any of which
will keep engine running at 1500 +_.
I have taken the carberater and fuel pump off running engine with no effect.
Also cleaned points in both mags.
Any ideas?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480534#480534
---
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Message 7
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| Subject: | Re: Chinese rebuild engine |
I spoke to Bob this afternoon and he said he removed and replaced the carbu
retor using the one from the old engine and there was no difference in the
way it ran.Dennis
From: Walter Lannon <wlannon@shaw.ca>
To: yak-list@matronics.com
Sent: Thursday, May 31, 2018 9:59 PM
Subject: Re: Yak-List: Re: Chinese rebuild engine
The engine was most likely overhauled about 30 years ago.=C2- The inhibit
ing
oil, in normal circumstances for a military operation, would be cleaned out
and re-applied in an absolute maximum of 6 years.=C2- It is "running" on
the
start solenoid and the primer NOT the carburettor.
You must follow the de-inhibiting process in the manual TO THE LETTER and
beyond since the oil has long since turned to hard grease.=C2- Particular
ly
true for the carburettor but applies to everthing they list in the manual.
Once you get serious and spend a few days on due diligence it will start an
d
run like a top.=C2- Do not mess with the point gap setting.=C2- The fac
tory will
have set these
at exactly 0.3 mm (0.012").=C2- Just make sure they are perfectly clean
Of course you have already confirmed that the carburetor ambient air tube i
n
the carb. throat is not blocked.
Cheers;
Walt
-----Original Message-----
From: Flibob
Sent: Thursday, May 31, 2018 3:22 PM
Subject: Yak-List: Re: Chinese rebuild engine
Still working on this engine. Starts but won't run unless 1. Throttle is
pumped constantly or 2 wobble is pumped or 3 primer is pumped.=C2- Any of
which
will keep engine running at 1500 +_.
I have taken the carberater and fuel pump off running engine with no effect
.
Also cleaned points in both mags.
Any ideas?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480534#480534
---
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S -
WIKI -
-
=C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.
Message 8
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| Subject: | Re: Chinese rebuild engine |
-----Original Message-----
From: Walter Lannon
Sent: Thursday, May 31, 2018 6:56 PM
Subject: Re: Yak-List: Re: Chinese rebuild engine
The engine was most likely overhauled about 30 years ago. The inhibiting
oil, in normal circumstances for a military operation, would be cleaned out
and re-applied in an absolute maximum of 6 years. It is "running" on the
start solenoid and the primer NOT the carburettor.
You must follow the de-inhibiting process in the manual TO THE LETTER and
beyond since the oil has long since turned to hard grease. Particularly
true for the carburettor but applies to everthing they list in the manual.
Once you get serious and spend a few days on due diligence it will start and
run like a top. Do not mess with the point gap setting. The factory will
have set these
at exactly 0.3 mm (0.012"). Just make sure they are perfectly clean
Of course you have already confirmed that the carburetor ambient air tube in
the carb. throat is not blocked.
Cheers;
Walt
-----Original Message-----
From: Flibob
Sent: Thursday, May 31, 2018 3:22 PM
Subject: Yak-List: Re: Chinese rebuild engine
Still working on this engine. Starts but won't run unless 1. Throttle is
pumped constantly or 2 wobble is pumped or 3 primer is pumped. Any of which
will keep engine running at 1500 +_.
I have taken the carberater and fuel pump off running engine with no effect.
Also cleaned points in both mags.
Any ideas?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=480534#480534
---
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