Today's Message Index:
----------------------
1. 02:09 AM - Re: 912 UL Intake Manifold Pressures (davidjoyce@doctors.org.uk)
2. 05:49 AM - Re: 912 UL Intake Manifold Pressures (Brian Davies)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: 912 UL Intake Manifold Pressures |
Jon, I believe I had a rather similar thing quite a few years ago when
my throttle cables were run in a not symmetrical pattern with one
following tighter bends. Regards, David Joyce, GXSDJ
On 2017-10-20 20:28, italianjon wrote:
>
> 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 [1]
>
Links:
------
[1] http://forums.matronics.com/viewtopic.php?p=473713#473713
[2] http://www.matronics.com/Navigator?RotaxEngines-List
[3] http://forums.matronics.com
[4] http://wiki.matronics.com
[5] http://www.matronics.com/contribution
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | 912 UL Intake Manifold Pressures |
Sticking throttle cables?
Brian Davies
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Kevin
Klinefelter
Sent: 21 October 2017 05:21
Subject: Re: RotaxEngines-List: 912 UL Intake Manifold Pressures
--> <klinefelter.kevin@gmail.com>
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:
>
> --> <williamtsullivan@att.net>
>
> 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.
>
>
>
>
>
>
>
>
---
This email has been checked for viruses by AVG.
http://www.avg.com
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|