Today's Message Index:
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1. 05:48 AM - Re: Carb sync issue, Another thought provoking problem (william sullivan)
2. 08:51 PM - Re: Carb sync issue, Another thought provoking problem (Roger Lee)
3. 09:49 PM - Spark Plug Hole Thread repair (paul perry)
Message 1
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| Subject: | Re: Carb sync issue, Another thought provoking problem |
=C2- I would start with an air leak at the carb socket.
=C2-
=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2
-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-
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-=C2-=C2-=C2-=C2- Bill Sullivan
=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2
-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-
=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2
-=C2-=C2-=C2-=C2- Windsor Locks, Ct.
=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2
-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-
=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2-=C2
-=C2-=C2-=C2-=C2- Kolb FS, 447
--- On Thu, 5/12/11, Roger Lee <ssadiver1@yahoo.com> wrote:
From: Roger Lee <ssadiver1@yahoo.com>
Subject: RotaxEngines-List: Carb sync issue, Another thought provoking prob
lem
Hi All,
Another mind probing problem and I=99ll give the answer in a day or t
wo after a few tries at an answer.
You just pulled the engine for the Rotax 5 year rubber replacement maint. E
verything is back on, oil purged and new plugs. It=99s time for the c
arb sync. You do your mechanical sync and head out to run the engine for th
e pneumatic sync. You start up and everything looks good and the gauge need
les at idle are only 1=9C of vacuum off and the idle is 1750. You thr
ottle up to 3500-3800 rpm to start the high rpm sync. The needles here are
4=9C of vacuum off. So you adjust the bowden cables to sync the two c
arbs and you run out of adjustment. You shut down make a cable length adjus
tment=C2- on the throttle arm and restart. Now the gauge needles at idle
are 7=9D-8=9D of vacuum off at idle. (Frack) You try and try to
get them closer, but the left carb doesn=99t seem to adjust. The eng
ine is running rough and is now down to 1620 rpm. This particular plane has
a Dynon D120 EMS with all the temps available to you. Oil temp, CHT and oi
l pressure are good and normal.
The EGT temp span warni!
ng is flashing yellow which means your EGT=99s have a span greater th
an 120F and that=99s about where they are. One EGT is 1050F on #4 cyl
while the other is 900F on #3 cyl. You just can=99t seem to balance
these carbs.=C2- =9CFrack=9D
NOW WHAT AND WHY?
By the way these thought provoking problems I give are real problems that h
ad a particular solution. I post these in the hopes that some day if you ha
ve something similar you may remember and find a quick=C2- and painless s
olution.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080=C2- TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=339729#339729
-
List
S WEB FORUMS -
on Web Site -
=C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.
Message 2
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| Subject: | Re: Carb sync issue, Another thought provoking problem |
Hi All,
Here is the answer to this little problem. Here is a couple of tattletale signs
that help point the way.
1. You just finished a full hose change which includes pushing new
rubber hose through the fire sleeve.
2. On startup it ran fine for about 30-seconds to a minute and the idle
was within 1 vacuum at first.
3. The high rpm adjustment at 3500-3800 rpm was no problem to
adjust.
4. When it was throttled back to idle again the needles were split 7-8
of vacuum.
5. The right carb would adjust with the idle stop screw and the gauge
needle would move and was about 13 of vacuum.
6. The left carb was at 20 of vacuum and the idle stop screw didnt
seem to make any difference.
7. Applying the choke made the engine smooth again and the needles
move to within 1 of each other.
8. The rpm at idle is having a hard time getting above 1650 rpm.
9. EGT split is too far. The left carb is running 150F hotter (1050F) than
the right carb at 900F.
(p.s.** Next time someone says that EGT temps arent that helpful on a 912
you will know different in a few minutes)
So right off the bat you know its not electrical. You have an extremely high suspicion
that it involves the left carb and something with the idle. The vacuum
at 20 is way too high and the engine is rough because the carbs arent balanced.
So now you need to stop the carb balance and follow a logical diagnostic pattern
to a solution.
1. Pushing rubber hose through fire sleeve. Possible fuel line debris.
2. Left carb pulling way too much vacuum at idle only. High rpm is
smooth and can balance.
3. Left carb wont adjust at idle.
4. Left carb EGTs running hotter at lower rpms.
So everything points to the left carb. It also points to the low side of the rpms
around idle and not the higher rpm settings.
So what is it that affects the low rpms at idle?
So we need to take a look at the left carb and if all you do is pull the bowl and
look it was and could be nice and clean.
HMMMMM!
THE IDLE JET AND or CIRCUIT may be restricted.
The only way to do this right is pull the entire carb and pull all the jets. Use
air pressure and carb cleaning spray with the small red tube on a can of carb
cleaner. Clean and flush every orifice no matter what you think, but pay special
attention to the idle circuit.
When this was done a small piece of red silicone long and about as thick as a
thread comes out. It was tucked back up in the idle circuit and would not have
come out without the flush or air pressure. The carb was re-assembled and the
carb sync went well and was not an issue any longer.
I post this in the hopes that if you ever run across this scenario you will know
what to do and save yourself all those extra hours of banging your head against
the wall looking for the solution.
Good Luck!
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=339820#339820
Message 3
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| Subject: | Spark Plug Hole Thread repair |
Hi all, Looking for input from anyone that may used a Heli-coil, Time-sert, or
other thread insert system to repair a spark plug hole/threads in a 912. I have
some damaged threads in the bottom hole on my #2 cylinder and I am not sure
if it is going to seal up or not at this point, and I am considering my options.
If anyone has successfully used a product, I would appreciate knowing which
product , part no., where you purchased etc. Thanks, Paul Perry (Bloomfield,
MO)
Kitfox IV Speedster 912UL
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=339823#339823
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