Today's Message Index:
----------------------
1. 07:18 AM - Re: Float Level (Chuck Deiterich)
2. 07:27 AM - SB18-1 (Chuck Deiterich)
3. 10:06 AM - Re: Re: Float Level (Andy Silvester)
4. 12:20 PM - Re: Re: Float Level (THOMAS SMALL)
5. 02:25 PM - Float Level (RONAL SMITH)
Message 1
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Lynn,
I am sure I have a needle with several grooves.
When I replaced the float needle with one that has a stronger built in
spring (black), I did not readjust the float. The spring in the old needle
(orange) would compress at 1.5 Oz, while the spring in new needle takes 31
Oz to compress (yes 20 times more). This means that any compression of the
weaker spring would effectively have a higher float level. Thus my float
may be a bit low. The 255 main is larger than what Jabiru now puts in the
Bing. SB 18-1 says mine came with a 250 but it did not, as the main jet
size is scribed in the side of the carb body and on the jet itself. Lately
they are using a 245 main jet. Needle jet sizes can be misleading as the
needles used are different.
Chuck D.
>
> Time: 04:47:22 PM PST US
> From: Lynn Matteson <lynnmatt@jps.net>
> Subject: Re: JabiruEngine-List: Float Level
>
>
> The Bing manual for the carb says NOT to change the float (from what
> they suggest) to cure a problem, but to cure the problem by
> addressing either the main, the needle jet or the jet needle,
> whichever "neighborhood" the problem resides in (my analogy). I've
> read of guys who have adjusted the float height, but Bing says not
> to. Are you sure you have a "lowerable needle"? Mine is not, having
> only one groove for the snap ring.
>
Message 2
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Lynn,
SB18-1 also says for my serial number (988) the needle jet is 276 (which
it is) and the Bing needle is in the second position from the bottom.
Chuck
PS I like this forum better than yahoo.
Message 3
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Chuck,
You did the right thing to change the float needle for the stronger (spring)
one as it gives a better seating. However, I would follow Jabiru's advice
NOT to try adjusting the mixture with the float level. You might get away
with it, but our advice was always to change mixture settings on the
pre-economy tuning by raising or lowering the jet needle for fine
adjustment, and if this wasn't enough, change the needle jet for a bigger
one and reset the needle to the 'standard' position which is groove #2, or
one-up from the bottom. If the Wide-Open-Throttle (WOT) setting was too
rich, you could go to a smaller main-jet size but as others have said here,
the relationship between the needle shape and resulting jet orifices (?)
meant that in practice, you could actually remove the main jet completely
and there would be no real difference in WOT mixture, because the fuel still
has to get past the needle jet, which at most throttle/slide positions,
controlled the mixture. The economy tuning definitely improved the cruise
and WOT mixture relationships with a new needle shape, so they went for just
jet-changing rather than (also) needle height adjustment for mixture
alteration. This is why the 'older' straight-tapered needles have 4 grooves
for adjustment, but the new economy needles only have one. The guy who
developed the new needle shape told me he'd prefer the new setup to be
called 'more tunable' rather than 'economy' as it is the needle that
provides the right relationship now between cruise (relatively lean) and WOT
(relatively rich). Unfortunately, the new setup got off to a poor start as
they'd not allowed for the over-lean conditions present in the carb /
induction when operating in lower temperatures, hence with experience the
successive guidance to go bigger on jets to richen the whole range, but
particularly cruise.
You may also be unaware that Jabiru went through a phase a few years back of
drilling-out jets to achieve the required mixture, so what was stamped on
the jet wasn't necessarily the size of the hole.....This was from memory on
2200s before the year 2000, or so, but ask your dealer as they have factory
information (I'm afraid I don't at present). To compound the issues, my
understanding is that the sizes stamped on main jets don't correspond to the
jet diameter, but on needle jets they do! This means a 2.80 needle jet has a
2.80mm hole, but I'm pretty sure a 255 main jet isn't 2.55mm. I have no clue
why this is.
Andy
-----Original Message-----
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of Chuck
Deiterich
Sent: 28 April 2008 15:16
Subject: JabiruEngine-List: Re: Float Level
Lynn,
I am sure I have a needle with several grooves.
When I replaced the float needle with one that has a stronger built in
spring (black), I did not readjust the float. The spring in the old needle
(orange) would compress at 1.5 Oz, while the spring in new needle takes 31
Oz to compress (yes 20 times more). This means that any compression of the
weaker spring would effectively have a higher float level. Thus my float
may be a bit low. The 255 main is larger than what Jabiru now puts in the
Bing. SB 18-1 says mine came with a 250 but it did not, as the main jet
size is scribed in the side of the carb body and on the jet itself. Lately
they are using a 245 main jet. Needle jet sizes can be misleading as the
needles used are different.
Chuck D.
>
> Time: 04:47:22 PM PST US
> From: Lynn Matteson <lynnmatt@jps.net>
> Subject: Re: JabiruEngine-List: Float Level
>
>
> The Bing manual for the carb says NOT to change the float (from what
> they suggest) to cure a problem, but to cure the problem by
> addressing either the main, the needle jet or the jet needle,
> whichever "neighborhood" the problem resides in (my analogy). I've
> read of guys who have adjusted the float height, but Bing says not
> to. Are you sure you have a "lowerable needle"? Mine is not, having
> only one groove for the snap ring.
>
Message 4
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> To compound the issues, my
> understanding is that the sizes stamped on main jets don't correspond to
> the
> jet diameter, but on needle jets they do! This means a 2.80 needle jet has
> a
> 2.80mm hole, but I'm pretty sure a 255 main jet isn't 2.55mm. I have no
> clue
> why this is.
Andy,
Nor do I, but I can verify that what you say about "older" jets being
drilled out is true. On my #051 3300 both the needle jet and the main jet
had been drilled out and were not close to what was stamped on them.
I took to using my set of # drills to figure out what I had before
experimenting. Really would have been nice to know that from the factory.
Jabiru seem to be blind to many common sense pieces of info their customers
deserve.
cheers jeff
Message 5
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My understanding is that any EGT temp. 1400 F or below is fine with the
Jabiru 2200 engine. I was getting temps up to 1500, so I changed the
needle jet from 276 to 280 and the main jet from 220 to 240. Now my
high temp in cruise is 1375 with the OAT 65 F or above. My engine is
Ser. No. 2030.
Ron Smith
Kitfox 4 with Jabiru 2200
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