912ul carburator

[Bud Davidson]

i am finished with the fuselage and engine installation, leaving one wing remaining for repairs from hurricane damage. So, I am close to creating the paperwork for registration and getting the airworthiness certificate. At this point I have two questions on the engine and carb. Searching the rotax service bulletins I find one that suggests I need to replace the floats in the Bing Carbs on my 912. ASB 912 069 of 07/22/2016 is the reference.

searching the internet I cannot find a source of these floats. Anyone made this replacement??

also. I had to remove the oil reservoir and now believe I have to bleed the oil system since I cannot now get the "burp" when pulling thru the prop. Any suggestions??

[Av8r3400]

Weigh the floats. If they are in spec (less than 3.5g each), DO NOT REPLACE THEM! Replacements are difficult to get and have not been the best quality since all of the float BS started a couple of years ago.

If there is air in the oil system, or suspected to be in the system, it should be purged before starting the engine. (Procedure (https://www.manualslib.com/manual/847567/Rotax-912-Series.html?page=78#manual))

[jrthomas]

On your burping issue, I had the same problem. After trying everything I knew, I called Roger Lee. I should have talked to him 1st. Here's what I learned. The model 4 has a short engine mount so the engine is right back near the firewall. The ideal place for the oil tank doesn't exist on the 4 so it has to be mounted in the only place available, up high on the firewall. Later model Kitfoxes have the engine moved forward and the oil tank is mounted down low. Roger explained that there's 2 reasons to burp a cold engine, to make sure there's not a hydraulic lock and to check the oil level. The solution is to pull the prop through by hand a few blades before cold starting. Then warm it up and go fly. When you're finished flying burp it by pulling it through each compression stroke slowly. This is what I do and mine will burp after only 10 or 12 blades. I always do it as soon as I can after shutting it down. If I burp mine cold it takes forever and the oil level will always show a lower level than it shows when I burp it hot. Hope this solves you problem. James Thomas

[Bud Davidson]

My thanks. This really helps. Tomorrow is "burp" day .

[mscotter]

Thursdays shall forever be stuck in my mind now as "Burp Day"!!
:D:D:D

[Av8r3400]

My thanks. This really helps. Tomorrow is "burp" day .

PLEASE! If you have removed the oil tank, you NEED to purge the air from the oil system before you start the engine. Otherwise you can very easily destroy the engine by oil starvation.

Regular "burping" does not do this purge.

[Bud Davidson]

"Burp" day starts with purge.

[Dusty]

when doing an oil change the oil filter can't be fully primed as when getting fitted most of the prime runs out. Some of us now leave the filter loose and swing the prop by hand till the air stops bubbling out,(like bleeding a diesel system)
This air would be otherwise introduced onto the lifter gallery.
Positive oil pressure is also confirmed without having a helper watching the pressure guage.
As a side note
We had one individual who who did his own oil change and didn't follow the correct procedure at all.
When he couldn't get pressure he decided his guage must be faulty:confused:
so decided to do some circuits.
He landed on his third circuit when his engine began to rattle,exit one 100hp912.
His conrods were blue and the bearings had disappeared!
These engines are tough,not many would have kept running for so long.

[kitfox2009]

I understand the need to recharge the system if the lines and tank have been removed but for normal oil changes I have been just cranking the engine over with the starter a few times until oil pressure shows. Modules off. It's over 750 hours now with no issues.
Is this not the the correct way?
Don

[jrthomas]

[QUOTE=Dusty;70725]when doing an oil change the oil filter can't be fully primed as when getting fitted most of the prime runs out. Some of us now leave the filter loose and swing the prop by hand till the air stops bubbling out,(like bleeding a diesel system)
This air would be otherwise introduced onto the lifter gallery.

This is a new one on me. Can you explain in a little more detail? Are you prefilling the oil filter? It sounds logical but I've just not heard about this technique. Anyone else heard of this? James Thomas

[Bud Davidson]

The purge was easier than I expected. removed lower plugs, hand propped 20 blades and showed 20 psi (had to remember to turn master on for the electric gauge to work)
Ran the engine until oil temp reached 120, psi started at 60 and after warming steadied at 40. too easy to not do upon oil change or other removal of oil from system. will be SOP.
after running the engine and sitting in it I am anxious to get the wing done and both painted. Need to get started on the paper work.

[Dusty]

When I was in the trucking industry 20 yeas ago this was standard practice as any air had to go somewhere, removing injectors wasn't an option.Most diesels will start on first compression so there was a brief moment when the engine was running with no pressure feed.There were certain models of cummins that would supposedly loose prime and do damage .
Maybe it isn't a big deal anymore as some manufacturers insist on mounting filters upside down which makes filter changes even more messy :mad:and pre filling impossible.
I consider it still good practice and on a rotax virtually eliminating all air is only a good thing
Cheers
Dusty