Today's Message Index:
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1. 12:55 AM - Re: Rotax 912 crossover carburetor link (R Holder)
2. 06:21 AM - Re: Rotax 912 crossover carburetor link (Noel Loveys)
3. 07:48 AM - Re: Rotax 912 crossover carburetor link (george may)
4. 07:55 AM - Diagnostic tool - AC Power tester (Roger Lee)
5. 10:49 AM - Re: Rotax 912 crossover carburetor link (dcsfoto)
Message 1
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| Subject: | Re: Rotax 912 crossover carburetor link |
ronlee wrote:
> Has anyone put together some sort of crossover rod for
> linking the Rotax 912 carburetors together? This is not
> a new idea, as I have seen this sort of link between
> carburetors on other engines. I have mine working fine
> on my CH701, but must say it was a chore routing a
> cable to each carburetor, trying to keep them the same
> length so they advance properly, and making the whole
> mess look neat. If they were linked together by a rod
> of some sort and activated by one cable at one
> carburetor it sure would help cleaning up under the
> cowl. The carburetors would probably stay
> synchronized forever..
I have spent a lot of time attempting this. The problem
is that the starboard carb is about an inch further
forward than the port one, so the normal (SU carburretor)
linkage doesn't work.
It might be possible with a linkage that is perpendicular
to the crankshaft with unequal length operating rods to
the carbs, but the geometry is tricky. I decided that the
geometry required the cross shaft to be in a certain place
which went straight through the inlet manifold (headers !)
In the interests of avoiding all those bends I designed a
connection box with a single cable from the throttle to a
box which connected the one cable to two much shorter ones
that went directly to the carbs. They went round a
cylinder. It was very smart, but the PFA didn't like it !
I am contemplating reducing the length of the cables
considerably (in the Europa they are over 6 foot long and
thread around a lot) making the cable run more direct so
less friction and less bends. I have spare cables from my
previous attempt to smoothen off the engine, so that will
be next !
The smoothness of the engine is very very dependent on the
balance of the carbs, and one flt on the cable adjustment
makes a big difference ! (Maybe I am over sensitive !)
Richard
G-OWWW
High Cross
Message 2
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| Subject: | Rotax 912 crossover carburetor link |
There are several cars etc that use linkages to join two or three carbs
together... but... Those carbs dont have the diaphragms and additional
parts in them that the Bing 64 has. This I expect is why the 64 is mounted
on rubber and springs and as has been mentioned, that doesn't lend itself to
linkages. I'm sure you could make a more secure method of mounting the
carbs and then install links but that is going to be heavy.
Noel
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of R Holder
Sent: Wednesday, February 27, 2008 5:23 AM
Subject: Re: RotaxEngines-List: Rotax 912 crossover carburetor link
ronlee wrote:
> Has anyone put together some sort of crossover rod for
> linking the Rotax 912 carburetors together? This is not
> a new idea, as I have seen this sort of link between
> carburetors on other engines. I have mine working fine
> on my CH701, but must say it was a chore routing a
> cable to each carburetor, trying to keep them the same
> length so they advance properly, and making the whole
> mess look neat. If they were linked together by a rod
> of some sort and activated by one cable at one
> carburetor it sure would help cleaning up under the
> cowl. The carburetors would probably stay
> synchronized forever..
Message 3
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| Subject: | Rotax 912 crossover carburetor link |
For those interested in one solution to the linkage issue, check out Klaus'
s
http://www.utdallas.edu/~klaus/Airplane/airplane.html
George May
601XL 912s
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Connect and share in new ways with Windows Live.
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08
Message 4
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| Subject: | Diagnostic tool - AC Power tester |
Hi Guys,
Here is a little diagnostic tool to keep in your little bag of tricks for the 912
series engine.
If you have a rough running engine after a mag check you can do a quick check on
which plug/s is affected.
If you have a mag drop in the 300 rpm range you have one cylinder having an issue
and if the mag drop is 800-1000rpm then it is two cylinders.
First head on out to the local hardware store and pick up an AC electric household
socket/outlet power tester. Get one that works when you hold it up by the
socket and a light comes on. These run about $12. They are usually all plastic
and have a battery inside and about the size of a writing pen. You do not want
one that has to be plugged into the socket, but one that you just hold up by
the electric power socket/outlet and the light comes on if there is power.
The spark plugs on your plane are AC current. If you have dropped a cylinder you
can test each wire quickly and ascertain which plug/s are affected. Start the
engine and have someone you trust in the cockpit. Have the cowling's off. While
the engine is running at approximately 2000rpm hold the tester up by or against
the plug wires one at a time. The light will come on for all good plug firings.
When you hold it up against a bad wire the light will not work or it will
flash very intermittently. You now have at least identified the problem plug.
Now you need to start checking the system back towards the ignition module. If
you are dropping only one plug then it is most likely a bad connection at the
plug boot, at the ignition coil or where the ignition coil plugs in at the 6 pin
connector. Don't discount a bad spark plug either. These are not mags as we
call them all the time, but ignition coils. The plug wire is replaceable and
screws into the coil. Check this area for a connection. Then check the 6 pin connector
from the coils to the ignition module for a good connection.
This is as far as this tip goes as it gets more involved going any further. If
you are dropping only 300 rpm which is one cylinder on the mag check you need
to look for your problem in a bad connection between the spark plug and the ignition
module. You may want to replace the plug as it could be the offender, also.
This tip was mainly for you to pick up an AC power tester to check plug wires.
--------
Roger Lee
Tucson, Az.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=166565#166565
Message 5
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| Subject: | Re: Rotax 912 crossover carburetor link |
I looked at the 601 setup,looks to me like when the engine vibrates the rods are
attached to a linkage fixed to the firewall and will pull or push the carbs
different .
My Kitfox 7 throttle is an aircraft throttle that is split,and each end is secured
at the carb. each carb is moved the same.
why reinvent the wheel.
David Kitfox 3 and 7
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=166608#166608
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