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1. 02:32 AM - Hard starting.. help required from round engine pros (JL2A)
2. 05:06 AM - Re: Hard starting.. help required from round engine pros (A. Dennis Savarese)
3. 07:20 AM - Re: Hard starting.. help required from round engine pros (George S. Coy)
Message 1
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| Subject: | Hard starting.. help required from round engine pros |
Gentlemen,
We have a Jacobs R755 powered Agcat used for commercial Joy Flights.
We also have two CJ6s, and realise this is a eastern bloc forum but hopefully there's
a few of you here that have experience with other types of round engines
(paging George Coy??!)
The aircraft has not done multiple flights in a day for many years, however we
are working the aircraft quite a bit lately (which is great!) and it is proving
to be a real sob to start, at seemingly random times.
Once running, the thing is great and purrs smoothly and runs well, however the
starting sequence has many quirks, the most frustrating of which is the Im not
going to start at all
We have tried everything!
- prime like crazy while cranking. nothing
- flooded start, idle cut-off, throttle open, crank. nothing
- every possible variation of prime, from nothing to too much with all combinations
And when I say nothing, I mean nothing! Not a chug, cough, smoke, nothing. It is
like there is actually no spark at all. Unlit fuel vapour can be seen coming
from the exhaust whilst cranking.
The only thing that does seem to work is walking away, coming back 30 minutes later
and then shell start second blade! Unfortunately by then the customers have
been refunded and have left.
We have had the magnetos overhauled, shower of sparks inspected and all found serviceable.
We had some drag car racers as customers the other day and their comment was 'it's
like there's no spark'. Which is what it 'feels' like to us too. Too rich/lean
starting mixtures engines behave differently, with some cylinders firing
or not etc. This one is either perfect all 7 cylinders start, or absolutely nothing.
Obviously there is a spark, otherwise nothing would happen - but I'm thinking maybe
it is such a weak spark from the shower of sparks that the mixture has to
be juuuust right in order for it to go.
Would the starter be taking so much voltage that the SoS is not getting it's required
amount?
Any ideas are welcome!
Thanks in advance!
Anatole Mills
PS Sometimes while starting one jug will fire way early and drives the engine
backwards against the starter which makes us wince. Fear for the life of the starter.
This may be an independent problem. The R755 is timed to 31BTDC (running,
static)
PPS After operating the R985 and R755 the HS6A looks more and more like an engineering
masterpiece!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=465595#465595
Message 2
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| Subject: | Re: Hard starting.. help required from round engine pros |
You mentioned a shower of sparks as a possible culprit.=C2- We have seen
the same thing with the Huosai and M14 (not with M9-35's which are timed AF
TER TDC and in theory do not require a shower of sparks) engines as well an
d yes, a weak shower of sparks will cause the engine not to start.
What I typically do on the M14 and Huosai engines is test the shower of spa
rks by removing the shower of sparks lead from the magneto cap and placing
the tip of the wire about 3/8" to 1/2" inch from a metal surface.=C2- The
next step applies to an air start engine.=C2- We'll discuss your Jake sh
ortly.=C2- We make sure the air system forward of the main air valve is b
led off completely.=C2- This eliminates any residual air in the air lines
from rotating the engine when the start button is pressed.=C2- Next we t
urn on the battery and the ignition switches and press the start button.=C2
- With the shower of sparks held (by a second person) or held in place cl
ose to a metal surface in the engine compartment, the shower of sparks lead
should jump a spark from the tip of the wire to the metal surface.=C2- I
f the spark does not jump about 3/8" and we have to move the wire tip close
r to the metal to see the spark jump, we must conclude the shower of sparks
is weak and not generating enough energy to fire the spark plugs.=C2- Lu
ckily on the Huosai and M14 engines with their shower of sparks (ie: starti
ng coil which is identical on both engines) we can clean and adjust the poi
nts inside the unit and improve the spark.
Remember, whatever you see at the tip of the shower of sparks lead has to t
ravel down the spark plug wire to the spark plug.=C2- If the spark is wea
k at the tip of the wire, you can be assured it does not have enough energy
after traveling down the plug wire to the spark plug.
As for the Jake, don't assume because you recently had the shower of sparks
checked that it is outputting adequate spark.=C2- I would (if possible)
remove the magneto caps from the magnetos and then remove the shower of spa
rks lead from whichever magneto it is affixed to.=C2- Next do the same th
ing as described above: place the shower of sparks wire close to a metal su
rface.=C2- Then turn on the battery and ignition switches and press or en
gage the start switch.=C2- Yes the engine will rotate, but it can not sta
rt with the mag caps removed.=C2- But the shower of sparks wire should ju
mp a spark to the metal surface it is close to.=C2- Again, if the spark i
s weak, then the shower of sparks/starting coil is also weak.=C2- The wea
k spark will not fire the spark plugs.
Hope this helps.Dennis
From: JL2A <info@flyingwarbirds.com.au>
To: yak-list@matronics.com
Sent: Tuesday, January 31, 2017 5:31 AM
Subject: Yak-List: Hard starting.. help required from round engine pros
Gentlemen,
We have a Jacobs R755 powered Agcat used for commercial Joy Flights.
We also have two CJ6s, and realise this is a eastern bloc forum but hopeful
ly there's a few of you here that have experience with other types of round
engines (paging George Coy??!)
The aircraft has not done multiple flights in a day for many years, however
we are working the aircraft quite a bit lately (which is great!) and it is
proving to be a real sob to start, at seemingly random times.
Once running, the thing is great and purrs smoothly and runs well, however
the starting sequence has many quirks, the most frustrating of which is the
=C3=A2=82=AC=CB=9CIm not going to start at all=C3=A2=82=AC=84=A2
We have tried everything!
- prime like crazy while cranking. nothing
- flooded start, idle cut-off, throttle open, crank. nothing
- every possible variation of prime, from nothing to too much with all comb
inations
And when I say nothing, I mean nothing! Not a chug, cough, smoke, nothing.
It is like there is actually no spark at all. Unlit fuel vapour can be seen
coming from the exhaust whilst cranking.
The only thing that does seem to work is walking away, coming back 30 minut
es later and then she=C3=A2=82=AC=84=A2ll start second blade! Unfortu
nately by then the customers have been refunded and have left.
We have had the magnetos overhauled, shower of sparks inspected and all fou
nd serviceable.
We had some drag car racers as customers the other day and their comment wa
s 'it's like there's no spark'. Which is what it 'feels' like to us too. To
o rich/lean starting mixtures engines behave differently, with some cylinde
rs firing or not etc. This one is either perfect all 7 cylinders start, or
absolutely nothing.
Obviously there is a spark, otherwise nothing would happen - but I'm thinki
ng maybe it is such a weak spark from the shower of sparks that the mixture
has to be juuuust right in order for it to go.
Would the starter be taking so much voltage that the SoS is not getting it'
s required amount?
Any ideas are welcome!
Thanks in advance!
Anatole Mills
PS=C2- Sometimes while starting one jug will fire way early and drives th
e engine backwards against the starter which makes us wince. Fear for the l
ife of the starter. This may be an independent problem. The R755 is timed t
o 31=C3=82=C2=B0BTDC (running, static)
PPS After operating the R985 and R755 the HS6A looks more and more like an
engineering masterpiece!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=465595#465595
S -
WIKI -
-
=C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.
Message 3
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| Subject: | Hard starting.. help required from round engine pros |
It is most probably ignition problems. Either timing or weak spark at starting.
The Jacobs that I had was on a Cessna 195 had one magneto and one distributor
(like on a car). The distributor had an mechanical advance built into the rotor,
used a coil, points and capacitor. I recall the Jacobs on the Bamboo Bombers
( Cessna Bobcat) also had the same ignition system.
I also found out when the engine was warm or hot it was often hard to start with
the starter, but would easily start by hand propping. I suspected the voltage
to the coil was low during start and made a weak spark.
I replaced the coil, the capacitor, the lead from the coil to the distributor
on mine to help starting. I also installed fine wire plugs to help starting.
I had a friend with a 195 who had a reluctor wheel made to replace the cam, replaced
the points with a pick up from a Toyota and installed a capacitive discharge
system (the FAA did not know any better). It fired up every time.
The Franklin B9F engine on the SeaBee had a similar system and we always replaced
the coils and =with modern coils.
George
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