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dannparks
Sergeant Major
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Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
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Posts: 391
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Posted Wednesday, October 25, 2006 @ 07:02 PM
What are people's feelings about the Zenith 28 RXZ carburettor that is on the Rectimo 1200. I noticed that it doesn't have a mixture control. Is it altitude compensated in some way? The real question is, will it support a larger 1600cc engine, and would it be worth using -- as oposed to an AeroConversions carb or something else. Recommendations?
Thanks,
Dann Parks RF4D N2188
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Collin
General
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Location: McMinnville. Oregon
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Posted Wednesday, October 25, 2006 @ 08:52 PM
Hello,
Limbach used the 28 RXZ on some of there early 1700cc engines.
John Buckner (RF4D N7725) added a needle valve (or small ball valve) at the plemun and would control a vacuum leak. At altitude John would open the valve until the engine ran smoth.
-------------------- Collin Gyenes
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Posted Wednesday, October 25, 2006 @ 09:26 PM
Dan,
Bob Grimstead reports on the UK CFI site, that when upgrading his Rectimo from 1200 to 1385cc, he found it necessary to enlarge the jet from 2.0 to 2.5mm I would assume that you would need to enlarge it further when going to 1600cc ?
Details here: http://www.fournieruk.com/_forum/00000013.htm
Steve
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eugenio
First Sergeant
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Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
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Posted Thursday, October 26, 2006 @ 01:09 PM
Zenith 28RXZ is a good carburator, very simple (it was a tractor's engine carb) and is easily modifiable because it has very few parts.
It can be used with the 1.600 just enlarging slightly the main jet, that on the original is 1.25 . The 2 or 2.5 mm reported from someone, refers to the needle valve seat that on the carb used on the Rectimo is usually 2 mm, while in the Limbach 1700 or the Stamo 1500 was 1.5 mm because those engines were using the fuel pump.
Eugenio
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vpch
Private First Class
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Location: LFPH - France
Registered: Dec 2006
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Posts: 15
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Posted Friday, December 15, 2006 @ 05:45 PM
Recently, three french fourniers (including me) upgrades their engine from 1200cc to 1490 ( 1600's bore with 1200's strike) and 1600cc keeping their Zenith 28RXZ carburator. The major problems we encounter is a higher sensivity to carburator icing due to the higher speed/lower pressure in the venturi and a higher cylinder/oil temperature...
-------------------- Vinc. RF3 #13 F-BLXE
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sabatig
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Posted Friday, January 26, 2007 @ 10:25 AM
anyone know where I can get a RXZ 28 replacement? I have looked everywhere but to no avail...what other options do I have on a 1200 Rectimo engine?
thanks
Gino
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Collin
General
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Location: McMinnville. Oregon
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Posted Friday, January 26, 2007 @ 01:57 PM
Parts for Zenith RXZ 28
Karl Pieper GmbH
Viktoriastr. 50
D-32423 Minden
Tel. 0571 / 34088
Fax. 0571 / 34454
email@karlpieper.com
http://karlpieper.com/
-------------------- Collin Gyenes
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eugenio
First Sergeant
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Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
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Posted Monday, January 29, 2007 @ 02:16 PM
Pieper has no more spare parts for the 28RXZ, except the bowl gasket and the needle valve. The carburator is no more available.
The only way to find one is to find an old engine equipped with that carb.
It was used on Rectimo 4AR1200, Limbach SL1700 EAA, Stark.Stamo SS1500.
For those operating on the Experimental class the carb can be exchanged with a Kohler carb as did Karl Pieper with the Stamo ss1500.
Eugenio
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patrick
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Posted Saturday, February 24, 2007 @ 05:29 AM
Zenith carb gaskets: one of the German CFI members and RF4 owner has the tools to cut Zenith gaskets.
I will take a batch of them to Gap.
Patrick
-------------------- Patrick, Speyer - Germany RF5 D-KOPF
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Collin
General
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Location: McMinnville. Oregon
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Posted Saturday, February 24, 2007 @ 05:09 PM
Hello,
Any toughts on making the 28 RXZ bigger?
When I find a spare 28 RXZ carbuertor, I would like to machine the to carburetor for a 30mm butterfly (maybe 31mm). And bore the venturi 2-3mm bigger.
-------------------- Collin Gyenes
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Donald
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Posted Saturday, February 24, 2007 @ 07:16 PM
I don't know if it would be possible to enlarge the bore as you suggest but you should take into account the gallery that supplies fuel to the idle port on the starboard wall of the bore. It is evident on the outside of the carb running back from the idle screw adjustment and on the flange that connects to manifold you will find a circular plug at the 3 o'clock position closing off the gallery. You will have to judge for yourself whether or not there is enough 'meat' in the casting for the enlargement.
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Collin
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Posted Thursday, March 1, 2007 @ 04:20 PM
Hi Donald,
I will have a look the carb, the engine is removed for a rebuild and installing 83mm pistons.
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Collin
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Posted Thursday, March 1, 2007 @ 04:21 PM
Does any one have a used 28 RXZ for sale?
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Donald
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Posted Sunday, March 4, 2007 @ 09:14 AM
Collin, I took my own carb off for cleaning yesterday and took a couple of photograph I thought would be of interest.
The first one is just a highlight of the gallery that feeds the slow running port. On the flange of my carb the white metal
blanking plug has been drilled out, the end of the gallery tapped and a brass grub screw inserted. Thus I can get access into the gallery for cleaning. Many years ago I had three in-flight stoppages due to dirt finding its way back down there and blocking the port.
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SteveBeaver
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Posted Sunday, March 4, 2007 @ 10:28 AM
Donald,
Between the IMG tags, you have to type the web address where the picture is published. - Email a copy to me at sbeaver@columbus.rr.com or to Collin, and we can publish it so that it can be linked to your message.
Steve
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Donald
Command Sergeant Major
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Posted Sunday, March 4, 2007 @ 03:49 PM
Steve, thanks for sorting that out. I figured that the address of the pictures had to go between the [img] tags and tried it with the path on my hard disk. Hadn't realised they had to be web URL's.
I hope the pictures are useful to Collin.
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Collin
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Posted Sunday, March 4, 2007 @ 09:58 PM
Thanks Donald for the pictures.
Maybe I will just open the venturi. I have worked Weber carbs and opened the venturis to 90% of the butterfly size.
Collin
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patrick
Sergeant First Class
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Location: Germany
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Posted Tuesday, April 10, 2007 @ 08:10 AM
Gasket for Zenith 28 carb.
The owner of the RF4 with the exhaust muffler has the tools to cut Zenith 28 Carb gaskets.
I asked him to make me some gasket sets.
Who is interested ?
He will take them to Gap - all free of charge.
Patrick
-------------------- Patrick, Speyer - Germany RF5 D-KOPF
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vpch
Private First Class
Gender: Male
Location: LFPH - France
Registered: Dec 2006
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Posted Tuesday, April 10, 2007 @ 11:24 AM
Me of course ! F BLXE
P.S. I prefer you bring them than you post them...
-------------------- Vinc. RF3 #13 F-BLXE
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sericson
Staff Sergeant
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Location: Lancaster, CA
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Posted Thursday, April 12, 2007 @ 06:49 PM
I'm looking for the gaskets also Patrick. If any are availible get them to Collin for me.
I'm also curious about the carb set up on the German's RF4. Looks like he has a ram air scoop and possibly a heat box.
Steve RF4-D N505SE
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patrick
Sergeant First Class
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Posted Friday, April 13, 2007 @ 06:11 AM
5 sets of carb gaskets are on the way to me ...
Patrick
-------------------- Patrick, Speyer - Germany RF5 D-KOPF
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Collin
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Posted Saturday, May 19, 2007 @ 09:56 AM
If there is still enough time to get 5 set of the gaskets to bring to the Gap. I would like to bring some home with me.
Many Thanks
see you next week
Collin
-------------------- Collin Gyenes
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vpch
Private First Class
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Location: LFPH - France
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Posted Sunday, June 17, 2007 @ 06:41 AM
Quote: | | Originally posted by Donald
Collin, I took my own carb off for cleaning yesterday and took a couple of photograph I thought would be of interest.
The first one is just a highlight of the gallery that feeds the slow running port. On the flange of my carb the white metal
blanking plug has been drilled out, the end of the gallery tapped and a brass grub screw inserted. Thus I can get access into the gallery for cleaning. Many years ago I had three in-flight stoppages due to dirt finding its way back down there and blocking the port.
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I had also two engine shut down recently and I also suspect the idle port of the carburator. Would you please send me your pictures of your modification ?
How often are you cleaning your carb ?
Thanks.
-------------------- Vinc. RF3 #13 F-BLXE
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vpch
Private First Class
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Location: LFPH - France
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Posted Sunday, June 17, 2007 @ 06:51 AM
It's OK for the pictures, I found the way to copy them...
-------------------- Vinc. RF3 #13 F-BLXE
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Donald
Command Sergeant Major
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Location: Scotland
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Posted Sunday, June 17, 2007 @ 11:59 AM
Hi. I usually clean my carb at least once a year at the annual inspection but I have on occasion done it when I thought the engine was not idling quite as it should. I have to say I have never SEEN dirt in my carburettor but after my three stoppages that tiny idle port was identified and after a good clean out the problem disappeared.
QED.
The product that I use for cleaning is called "STP Carb Cleaner" which I buy from a local car parts shop. It's a terrific solvent, contains toluene, and is great for cleaning up any aluminium castings that have got a little dull. I have also used it on aluminium castings and chain rings on my bike. It's pretty hard on paint, though.
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Bob Grimstead
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Location: Perth, Western Australia or West Sussex, England
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Posted Tuesday, December 2, 2008 @ 05:02 AM
Well, well, well!
Would you believe that I got precisely these symptoms at the aeros competition on Saturday.
After a long taxi out, just as I was about to line up, the engine stopped dead, just as though I had switched it off.
Determined to fly, if not to win, I hopped out and swung the prop, and it started again immediately.
I promptly lined up, took off and flew. Twenty sweaty minutes later (aerobatics sweaty, not worry sweaty) I landed and taxied back. Just as I approached the judges, my engine stopped again, just the same. Hopped out, started it, ran for three seconds and stopped again. Many helping hands pulled me the last couple of hundred yards.
I was pretty sure I knew what the problem was, although I always filter my fuel through one of those super-fine, mini-micron funnels. I have had the same trouble in the past on motorbikes and in our Champ.
Turned off the fuel, dropped the cowlings, cut the lock-wire, unscrewed the float-bowl plug, turned on the fuel for a few seconds, switched it off again, replaced everything, started up, took off immediately, flew home OK.
I've been down at the airfield for 33 days in the past 47, so I'm all 'airfielded-out' for now, but when I go back I'll whip off the carb and blow out all the jets and galleries.
Since I've flown 33 hours in her in the same 47 days, all aerobatics, what with the red Bull and that comp and all, she's due a nice wash, a good drink of fresh, quenching oil and a caressing wipe over with an oily rag.
I'll let you all know if I find anything concrete (or even dusty).
Yours, Bob
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Bob Grimstead
Captain
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Location: Perth, Western Australia or West Sussex, England
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Posted Saturday, January 10, 2009 @ 02:36 AM
Hi Guys,
Well, I took off the carburettor and thoroughly cleaned it out with carb cleaner as recommended by Steve or Collin.
Put it back on the aeroplane and tried to fly, but it would not produce enough power to take off.
Coughing and spluttering, the poor thing was clearly choking.
I think I must have dislodged that bit of dirt (or added some other bit of dirt) into the main jet.
I cleaned it all out again (but still could not see anything obvious in the dirty cleaning fluid).
Put it back, and now the aeroplane flies better than ever.
So much so that I was able to spin down to 800 feet and then fly four minutes of aerobatics without going below my legal 500 feet limit.
Cleanliness is next to Godliness as they say.
Yours, Bob
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Collin
General
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Location: McMinnville. Oregon
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Posted Friday, January 23, 2009 @ 01:35 PM
Hello,
Here are links to reworked Zenith 28 RXZ manuals.
Eugenio reworked the Italian version, Bob the English and Michel Leblanc the French version.
Thanks!
Italian http://www.cfiamerica.com/images/PDF/Carburatore%20ZENITH%2028RXZ%20.pdf
English http://www.cfiamerica.com/images/PDF/Carburettor%20ZENITH%2028RXZ%20.pdf
French http://www.cfiamerica.com/images/PDF/Carburateur%20ZENITH%2028RXZ%20.pdf
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Bob Grimstead
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Posted Sunday, January 25, 2009 @ 00:21 AM
Hello again Folks,
Those of you who have read this new carb info will have seen that Zenith suggest the float-bowl fuel level should be set at 9mm below the carb's main joint face, and there is no other mixture adjustment available to the owner except changing jet sizes. During the past couple of weeks, I have had a lot of 'fun' trying to achieve a good mixture.
I have here in Perth both (blue) HDO's carb and (red) WGN's carb – WGN is currently flying with our spare one. Both engines had been running fairly well, with no obvious signs of seriously rich or lean burning, although I am sure you are all aware that I have long felt (red) WGN was down on power. Recently, (Blue) HDO had also been slightly down on power, and that's why I started investigating the carburettor – and opened a big worm-can!
First, I swapped the carbs, but there was no perceptible difference in performance or anything else except a very slight change in idle rpm.
When I removed a spark plug from (blue) HDO, it seemed the aeroplane was running slightly weak. There was very little carbon on either the piston or the plug (1,250-hour engine, remember) and what there was had a light fawn/mushroom colour. This was a clue. Maybe the red one had always been running a little weak (it had always been hot, which kinda confirms that) and now the blue one had started running lean, too. But I don’t know why.
Both had standard 1.25mm main jets, both needle valve jets were correct at 2.5mm, and each had its aluminium washer properly in place. I checked the fuel flow, which was huge, much more than needed.
So, I asked for the float level setting. Eugenio told me this should be 9mm below the joint face, but when measured both these carbs had their fuel level at just 4mm below the joint face, which ought to have made them run rich, not weak.
OK, so it’s running a bit lean, although the fuel level is high. Let’s raise the float level even more, to see if we can get the ideal mixture. So I took out the washer, and the fuel level came up to maybe 1mm below the joint face on a level carb. That should do it. HDO flew brilliantly well – as well as it has ever done, and allowed that recent display with no height loss.
Unfortunately, whenever I stopped the aeroplane without switching off the fuel, fuel ran out of the carburettor and out of the bottom of the cowling. So it was probably doing that when throttled back in flight. This is a fire risk (and a waste) so I replaced the washer. The fuel level was once more 4mm below the carb’s joint face and the overflow stopped. I accepted the high fuel level, but then had reduced performance again.
So, then I borrowed a 1.25mm drill bit. When I measured this with both a micrometer and an electronic vernier calliper, it was slightly oversize, at 1.28mm. I ran it through the main jet, two minute slivers of metal spiralled out, so now I have a 1.28mm main jet.
I fly, and the aeroplane is still down on performance, but now I think it is a little too rich.
Next, I shall make up some aluminium washers of various thicknesses and experiment with different float levels, but I now have two further problems.
If the mixture has become lean on one engine, and is now becoming lean on the other, with no adjustments, why is this? Maybe the worn throttle butterfly spindle lets in air?
One is very slightly worn and loose, the other is a little worse.
Has anybody else suffered from this?
If so, how did you cure it?
And does anybody have a source for carburettor gaskets?
Mine have been off and on so often now, that the gaskets are starting to break up around their edges, and fibrous bits keep blocking the jets, leading to even worse performance, engine stopping, inability to get full power etc.
As usual, any actual experience (as opposed to pondering and theorizing) would be greatly appreciated.
Yours, Bob
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eugenio
First Sergeant
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Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
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Posted Sunday, January 25, 2009 @ 04:19 AM
For the gaskets you should ask Patrick Faucheron, he started the production of some set, and he said he will deliver free for all CFI members.
For the main jet, I produced some, ask Mike Millar, he should still have one or two, so as some drill bits of various diameter (1.25, 1.3)
Running rich or lean may also depend on the fuel used, today's unleaded fuel (rubbish in comparison to the red leaded premium mogas) is not intended for low compression engines like our VW, so it leaves lots of black deposits.
I had the same problem on my Lycoming powered Stinson, with leaded mogas it run perfectly, but when we switched to unleaded it started to leave a black soot out of the exhaust, so after some years of unleaded I had to go back to leaded avgas.
Mogas has also different formulations for winter or summer production, so this maybe a reason for engines different behaviour.
For the butterfly spindle, if the fit is loose, you must overhaul it putting a slightly oversize spindle after having reamed the seat. Ask a carb overhauler, it's not a hard job to do.
ciao
Eugenio
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