Carb setup - please help

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extra300s
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Carb setup - please help

Postby extra300s » Tue Sep 02, 2008 1:33 pm

Hi

I would like to know what you guys use to ensure the idling gap and piston position are the same on both carbs? (what kind of measuring tool)

When the engine is warmed up on the ground what EGT should I get?
Norml cruise EGT?

How many turns should the idling jet be turned out. Both exactly .5 turns out. Or could the two differ slightly. Looks like both my hex bolt and screw to the right of it is turned out more than the other one. Will take the air filter off just to make sure.

Please advice what I should do. Its on a Rotax 503

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Re: Carb setup - please help

Postby Harlequin » Tue Sep 02, 2008 4:46 pm

You are now getting technical Mr Karl.
Morph is the man!!!!!!
The tool you need is in my box in the hanger or make your own.
Two welding rods, knock the crap off, sand until smooth and you have some high tech instruments to put under the slide to see if both open to the same degree.
The fiddling with mixtures is another ball game.
Temp settings, RTFM. Or Morph.

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Re: Carb setup - please help

Postby Z-MRP » Tue Sep 02, 2008 6:22 pm

Ya, I use a drill bit to check both carb slide heights and then adjust from there to get desired idle speed. What you must first check is that the throttle cables are balanced as this will cause problems when adjusting the slide heights, ie one slide wont come low enough to balance with the other.Once you get the desired idle speed balancing is quiet simple, just adjust one carb idle screw and the motor with run alittle rough and if you go the opposite way on adjustment it will start to run very smooth. Once thats done give the motor a short full throttle to clear oil build up in the crack casing and recheck idle speed. EGT temp not really effected coz you are on the slow running jet, EGT is mainly effected from 3/4 to full throttle as you are now on the needle jet, so if its running a bit high on EGT then drop the clip one notch, think there is only one notch above or below centre notch as this is where you should be to start with. Another point is if your motor has done high hours you should replace the needle jet and needle as these wear and effects fuel consumption and performance. Hope this helps.
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Re: Carb setup - please help

Postby Z-MRP » Tue Sep 02, 2008 6:35 pm

The idle screw you referring to sounds like the air mixture screw, they should be the same and the number of turns out from full closed is in the rotax owners book, which if you are at sea level will be the standard settings give in the book. You can do a simple static check for mixture after running the motor on full throttle for a short while, kill the mags from this throttle position (Full) and remove your spark plugs, you are looking for a coffee color on the electrodes, you dont want to see any silver speckels as this is showing you are lean and probably high on EGT as well
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Re: Carb setup - please help

Postby Duck Rogers » Tue Sep 02, 2008 10:08 pm

Karl, I've got an entire article about this somewhere. Do a search for carb tuning or carb setup. My procedure works everytime. I think there's a few guys on here that will testify to this... vhpy
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Re: Carb setup - please help

Postby Koevoet » Wed Sep 03, 2008 7:03 am

Duck Rogers wrote:Karl, I've got an entire article about this somewhere. Do a search for carb tuning or carb setup. My procedure works everytime. I think there's a few guys on here that will testify to this... vhpy
viewtopic.php?f=13&t=6514&p=63211&hilit ... ing#p63211
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Re: Carb setup - please help

Postby Duck Rogers » Wed Sep 03, 2008 6:14 pm

Yep, that's the one vhpy vhpy
Airspeed, altitude, or brains....you always need at least two
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Re: Carb setup - please help

Postby John H Arnold » Thu Sep 04, 2008 8:00 am

Karl,

Jy sit met mense wat jou kan help op Wintervogel

Ronnie, Tobie, Ek en Shane kan jou help.

Jy moet net praat, Boetie
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Re: Carb setup - please help

Postby extra300s » Thu Sep 04, 2008 8:23 am

Dankie John. Ek het met Shne oor die foon gepraat. Hy gaan my Saterdagoggend help. Ek is Vrydag af so het gedink om dit dan te doen. Hou van sulke goed en dis hoekom ek maar net solank vra op microlighters om n idee te kry hoe mens dit doen.

Groete
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Re: Carb setup - please help

Postby Grumpy » Thu Sep 04, 2008 9:21 am

John H Arnold wrote:
Jy sit met mense wat jou kan help op Wintervogel

Ronnie, Tobie, Ek en Shane kan jou help.

Jy moet net praat, Boetie
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