Today's Message Index:
----------------------
1. 12:29 PM - 912 UL Intake Manifold Pressures (italianjon)
2. 02:08 PM - Re: 912 UL Intake Manifold Pressures (william sullivan)
3. 03:00 PM - 912 Running rough all of a sudden (Pete Christensen)
4. 05:05 PM - Re: 912 Running rough all of a sudden (william sullivan)
5. 06:34 PM - Re: 912 Running rough all of a sudden (John Hauck)
6. 06:48 PM - Re: 912 Running rough all of a sudden (DHeal)
7. 09:22 PM - Re: 912 UL Intake Manifold Pressures (Kevin Klinefelter)
Message 1
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| Subject: | 912 UL Intake Manifold Pressures |
Hi All,
I've been tracking a vibration for a while, and it has been very difficult. Carburettors
have been sync'd more than I've had hot dinners, plus other areas of
the engine. So far I've eliminated the propeller, gearbox
I noticed a strange effect today, and I'm unsure about it. Today, as a result of
a vibration plot taken last weekend, decided to carefully check the carburettor
sync again. The vibration plot is showing the vibration at half-crank and
twice-crank frequency.
I connected two vacuum gauges, so that I am reading absolute vacuum (i.e. 0" is
ambient and 10", for example, is 10" of vacuum).
>From about 10" up to 0", which corresponds to rpms of about 3400 up to 5400, the
carburettors are in sync. Below that they aren't.
At idle of about 1750/1800 rpm i get 12.5-13" in the port carb, and 15.5" in the
starboard carb.
I found Roger Lee's very good guide and thought that I could take out this idle
difference with the idle mixture screw. But it didn't really change anything,
no matter where set on the port carb. On the starboard carb it did have an effect.
The other strange symptom that I found is that if I take the engine to a fair speed,
say 4000 rpm and then quickly idle the throttle, then both carbs come down
to 15" in sync before the port carb raises to 12.5/13".
Compressions were checked 12 months ago, all ok. Carburettors we overhauled 12
months ago, all ok. Carb mounts renewed 12 months ago.
Any one seen this effect before?
I'm thinking of taking off the manifold and checking the O-rings between the engine
and manifold for leaks. And also stripping back the carbs, cleaning and rebuilding
them.
Anything else I should be thinking?
Best
Jon
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473713#473713
Message 2
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| Subject: | Re: 912 UL Intake Manifold Pressures |
Check the Viton seals in the enrichers. One could be deteriorating. Cheap and
easy fix, if that's it.
--------------------------------------------
On Fri, 10/20/17, italianjon <jon.catilli@gmail.com> wrote:
Subject: RotaxEngines-List: 912 UL Intake Manifold Pressures
To: rotaxengines-list@matronics.com
Date: Friday, October 20, 2017, 3:28 PM
"italianjon" <jon.catilli@gmail.com>
Hi All,
I've been tracking a vibration for a
while, and it has been very difficult. Carburettors have
been sync'd more than I've had hot dinners, plus other areas
of the engine. So far I've eliminated the propeller,
gearbox
I noticed a strange effect today, and
I'm unsure about it. Today, as a result of a vibration plot
taken last weekend, decided to carefully check the
carburettor sync again. The vibration plot is showing the
vibration at half-crank and twice-crank frequency.
I connected two vacuum gauges, so that
I am reading absolute vacuum (i.e. 0" is ambient and 10",
for example, is 10" of vacuum).
>From about 10" up to 0", which
corresponds to rpms of about 3400 up to 5400, the
carburettors are in sync. Below that they aren't.
At idle of about 1750/1800 rpm i get
12.5-13" in the port carb, and 15.5" in the starboard carb.
I found Roger Lee's very good guide and
thought that I could take out this idle difference with the
idle mixture screw. But it didn't really change anything, no
matter where set on the port carb. On the starboard carb it
did have an effect.
The other strange symptom that I found
is that if I take the engine to a fair speed, say 4000 rpm
and then quickly idle the throttle, then both carbs come
down to 15" in sync before the port carb raises to
12.5/13".
Compressions were checked 12 months
ago, all ok. Carburettors we overhauled 12 months ago, all
ok. Carb mounts renewed 12 months ago.
Any one seen this effect before?
I'm thinking of taking off the manifold
and checking the O-rings between the engine and manifold for
leaks. And also stripping back the carbs, cleaning and
rebuilding them.
Anything else I should be thinking?
Best
Jon
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473713#473713
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Message 3
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| Subject: | 912 Running rough all of a sudden |
Engine has been running great. Flew last weekend and then Wednesday was going to
fly. Started up and it was sounding rough at idle. I warmed up a minute and
advanced the throttle and it continued rough until it got to 3000 rpm. Let it
warm up some more then ran it at 3000 rpm for a couple minutes hoping to clear
up the problem. No joy. I ran it at high idle and turned off the fuel valve.
After a while it smoothed out just before it was starved for fuel. Opened the
fuel valve before it died and it ran smoothly for a few seconds before it began
to run rough again. Sounds like a carb problem where maybe one carb is getting
too much fuel. Mag check at 3k is normal. I dropped the float bowels and the
floats looked to be floating normally. Fuel looked clean. I had run on this
tank for a couple hours Saturday. Gascolator had clean fuel. Suggestions? Why
would a good,running engine start running rough after just a few days?
> On Oct 20, 2017, at 4:06 PM, william sullivan <williamtsullivan@att.net> wrote:
>
>
> Check the Viton seals in the enrichers. One could be deteriorating. Cheap
and easy fix, if that's it.
>
>
> --------------------------------------------
> On Fri, 10/20/17, italianjon <jon.catilli@gmail.com> wrote:
>
> Subject: RotaxEngines-List: 912 UL Intake Manifold Pressures
> To: rotaxengines-list@matronics.com
> Date: Friday, October 20, 2017, 3:28 PM
>
> "italianjon" <jon.catilli@gmail.com>
>
> Hi All,
>
> I've been tracking a vibration for a
> while, and it has been very difficult. Carburettors have
> been sync'd more than I've had hot dinners, plus other areas
> of the engine. So far I've eliminated the propeller,
> gearbox
>
> I noticed a strange effect today, and
> I'm unsure about it. Today, as a result of a vibration plot
> taken last weekend, decided to carefully check the
> carburettor sync again. The vibration plot is showing the
> vibration at half-crank and twice-crank frequency.
>
> I connected two vacuum gauges, so that
> I am reading absolute vacuum (i.e. 0" is ambient and 10",
> for example, is 10" of vacuum).
>
>> From about 10" up to 0", which
> corresponds to rpms of about 3400 up to 5400, the
> carburettors are in sync. Below that they aren't.
>
> At idle of about 1750/1800 rpm i get
> 12.5-13" in the port carb, and 15.5" in the starboard carb.
>
> I found Roger Lee's very good guide and
> thought that I could take out this idle difference with the
> idle mixture screw. But it didn't really change anything, no
> matter where set on the port carb. On the starboard carb it
> did have an effect.
>
> The other strange symptom that I found
> is that if I take the engine to a fair speed, say 4000 rpm
> and then quickly idle the throttle, then both carbs come
> down to 15" in sync before the port carb raises to
> 12.5/13".
>
> Compressions were checked 12 months
> ago, all ok. Carburettors we overhauled 12 months ago, all
> ok. Carb mounts renewed 12 months ago.
>
> Any one seen this effect before?
>
> I'm thinking of taking off the manifold
> and checking the O-rings between the engine and manifold for
> leaks. And also stripping back the carbs, cleaning and
> rebuilding them.
>
> Anything else I should be thinking?
>
> Best
>
> Jon
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=473713#473713
>
>
>
>
>
>
> The RotaxEngines-List Email Forum -
> Navigator to browse
> List Un/Subscription,
> 7-Day Browse, Chat, FAQ,
> - MATRONICS WEB FORUMS -
> via the Web Forums!
> - NEW MATRONICS LIST WIKI -
> Email List Wiki!
> - List Contribution Web Site -
> support!
>
> -Matt Dralle, List Admin.
>
>
>
>
>
>
>
>
Message 4
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| Subject: | Re: 912 Running rough all of a sudden |
Like I said, check the enricher seals. The one on my 447 had dissolved, making
it run very rich. I have very little experience with this, but your symptoms
gave me a good reminder. It will only take 5 minutes or so to pull each one
out and check.
--------------------------------------------
On Fri, 10/20/17, Pete Christensen <pchristensen10@austin.rr.com> wrote:
Subject: RotaxEngines-List: 912 Running rough all of a sudden
To: rotaxengines-list@matronics.com
Date: Friday, October 20, 2017, 5:58 PM
Pete Christensen <pchristensen10@austin.rr.com>
Engine has been running great. Flew
last weekend and then Wednesday was going to fly. Started up
and it was sounding rough at idle. I warmed up a minute and
advanced the throttle and it continued rough until it got to
3000 rpm. Let it warm up some more then ran it at 3000 rpm
for a couple minutes hoping to clear up the problem. No joy.
I ran it at high idle and turned off the fuel valve. After a
while it smoothed out just before it was starved for fuel.
Opened the fuel valve before it died and it ran smoothly for
a few seconds before it began to run rough again. Sounds
like a carb problem where maybe one carb is getting too much
fuel. Mag check at 3k is normal. I dropped the float bowels
and the floats looked to be floating normally. Fuel looked
clean. I had run on this tank for a couple hours Saturday.
Gascolator had clean fuel. Suggestions? Why would a
good,running engine start running rough after just a few
days?
Message 5
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| Subject: | 912 Running rough all of a sudden |
Make sure the idle jets and main jets are completely clean and clear when
you have the float bowls off.
Also, make sure the float bowl gaskets are sealing 100%. Best replace both
float bowl gaskets to be sure.
All the above can give you major headaches, although they are simple to
check and simple to cure.
john h
Kolb MKIII - 3,400.0+ hours
912ULS - About 850.0 hours on this one.
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Pete
Christensen
Sent: Friday, October 20, 2017 4:59 PM
Subject: RotaxEngines-List: 912 Running rough all of a sudden
--> <pchristensen10@austin.rr.com>
Engine has been running great. Flew last weekend and then Wednesday was
going to fly. Started up and it was sounding rough at idle. I warmed up a
minute and advanced the throttle and it continued rough until it got to 3000
rpm. Let it warm up some more then ran it at 3000 rpm for a couple minutes
hoping to clear up the problem. No joy. I ran it at high idle and turned off
the fuel valve. After a while it smoothed out just before it was starved for
fuel. Opened the fuel valve before it died and it ran smoothly for a few
seconds before it began to run rough again. Sounds like a carb problem where
maybe one carb is getting too much fuel. Mag check at 3k is normal. I
dropped the float bowels and the floats looked to be floating normally. Fuel
looked clean. I had run on this tank for a couple hours Saturday. Gascolator
had clean fuel. Suggestions? Why would a good,running engine start running
rough after just a few days?
---
This email has been checked for viruses by AVG.
http://www.avg.com
Message 6
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| Subject: | Re: 912 Running rough all of a sudden |
Sticky carb pistons? Remove air filters, reach inside carb throats, see if carb
pistons move up and down smoothly without sticking.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473724#473724
Message 7
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| Subject: | Re: 912 UL Intake Manifold Pressures |
To check the intake manifolds for leaks you can spray ether around them with the
engine running. If the RPM goes up you have a leak.
Kevin
> On Oct 20, 2017, at 2:06 PM, william sullivan <williamtsullivan@att.net> wrote:
>
>
> Check the Viton seals in the enrichers. One could be deteriorating. Cheap
and easy fix, if that's it.
>
>
> --------------------------------------------
> On Fri, 10/20/17, italianjon <jon.catilli@gmail.com> wrote:
>
> Subject: RotaxEngines-List: 912 UL Intake Manifold Pressures
> To: rotaxengines-list@matronics.com
> Date: Friday, October 20, 2017, 3:28 PM
>
> "italianjon" <jon.catilli@gmail.com>
>
> Hi All,
>
> I've been tracking a vibration for a
> while, and it has been very difficult. Carburettors have
> been sync'd more than I've had hot dinners, plus other areas
> of the engine. So far I've eliminated the propeller,
> gearbox
>
> I noticed a strange effect today, and
> I'm unsure about it. Today, as a result of a vibration plot
> taken last weekend, decided to carefully check the
> carburettor sync again. The vibration plot is showing the
> vibration at half-crank and twice-crank frequency.
>
> I connected two vacuum gauges, so that
> I am reading absolute vacuum (i.e. 0" is ambient and 10",
> for example, is 10" of vacuum).
>
>> From about 10" up to 0", which
> corresponds to rpms of about 3400 up to 5400, the
> carburettors are in sync. Below that they aren't.
>
> At idle of about 1750/1800 rpm i get
> 12.5-13" in the port carb, and 15.5" in the starboard carb.
>
> I found Roger Lee's very good guide and
> thought that I could take out this idle difference with the
> idle mixture screw. But it didn't really change anything, no
> matter where set on the port carb. On the starboard carb it
> did have an effect.
>
> The other strange symptom that I found
> is that if I take the engine to a fair speed, say 4000 rpm
> and then quickly idle the throttle, then both carbs come
> down to 15" in sync before the port carb raises to
> 12.5/13".
>
> Compressions were checked 12 months
> ago, all ok. Carburettors we overhauled 12 months ago, all
> ok. Carb mounts renewed 12 months ago.
>
> Any one seen this effect before?
>
> I'm thinking of taking off the manifold
> and checking the O-rings between the engine and manifold for
> leaks. And also stripping back the carbs, cleaning and
> rebuilding them.
>
> Anything else I should be thinking?
>
> Best
>
> Jon
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=473713#473713
>
>
>
>
>
>
> The RotaxEngines-List Email Forum -
> Navigator to browse
> List Un/Subscription,
> 7-Day Browse, Chat, FAQ,
> - MATRONICS WEB FORUMS -
> via the Web Forums!
> - NEW MATRONICS LIST WIKI -
> Email List Wiki!
> - List Contribution Web Site -
> support!
>
> -Matt Dralle, List Admin.
>
>
>
>
>
>
>
>
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