914

[skippydiesel]

6 hours ago, RFguy said:

I've had the jabiru ice up on the ground at high idle on a foggy cold morning. ...

Had the same problem with a C172 at Condobolin - she coughed & spluttered for a while, as I coaxed the engine to warm up & deliver carb heat - then all good.

[rhtrudder]

23 hours ago, RFguy said:

rightio then , sounds like just needs methodical approach to figure out what is going on. Yeah the O2 sensor (ULP only - no lead) would be a handy diagnostic I think.

I’m restricted on where I can fit the sensor, do you think it would get a good enough reading in the end of the muffler, the tail pipe is to small in diameter I reckon, the other end is taken up by the turbo body 

[RFguy]

dunno, I'd do some reading... others might be able to advise.

there might be some minimum temperature it has to be at to operate correctly, and location might influence that. 

[Methusala]

On 29/11/2022 at 9:07 PM, rhtrudder said:

 just thought a O2 sensor might show exactly what’s going on , cost $400, haven’t ordered it yet,

Hey mate, you can buy O2 sensors with digital gauge for about 40 dollars off ebay. Why pay more when you only want it as a diagnostic indicator? Just my 2c worth.

Rgds Don. PS. I used one when setting up EFI on a Aeropower vw conversion.

[RFguy]

but he's  a rotax owner Don, when a set of rings for a rotax is $250, money is no object.  (I just bought 6 ring sets for a jab project for less than the cost of a single ring set for the rotax) .

[Methusala]

Glenn, what was that about people in fragile, transparent houses? I know that you recently had a Rotax!

[facthunter]

He's only relating a fact. Some people can buy a product knowing  and acknowledging some of the downsides. Everything to do with a Rotax 9 series COSTS. The Chinese copy is no doubt cheaper. That doesn't mean I'd buy one or a 914.. Getting a good motor for a U/L is not easy. Fit and forget is a vague hope. Often an ancillary component lets a good motor down. Gravity feed is better than the best fuel pump.. If you need a pile of instruments to monitor your motor, get a less sensitive motor. It shouldn't be rocket science. mDo you want to be a Flight engineer OR a Pilot. All planes need a pilot. At the moment and IF  they don't WE DON"T want it because we want to FLY don't we?   MAN & Machine not man riding in machine. Nev

Edited December 1, 2022 by facthunter

[rhtrudder]

2 hours ago, Methusala said:

Hey mate, you can buy O2 sensors with digital gauge for about 40 dollars off ebay. Why pay more when you only want it as a diagnostic indicator? Just my 2c worth.

Rgds Don. PS. I used one when setting up EFI on a Aeropower vw conversion.

Did know that, apparently big difference between wide and narrow band , I’m a farmer so I’m used to throwing money away, 

[rhtrudder]

1 hour ago, facthunter said:

He's only relating a fact. Some people can buy a product knowing  and acknowledging some of the downsides. Everything to do with a Rotax 9 series COSTS. The Chinese copy is no doubt cheaper. That doesn't mean I'd buy one or a 914.. Getting a good motor for a U/L is not easy. Fit and forget is a vague hope. Often an ancillary component lets a good motor down. Gravity feed is better than the best fuel pump.. If you need a pile of instruments to monitor your motor, get a less sensitive motor. It shouldn't be rocket science. mDo you want to be a Flight engineer OR a Pilot. All planes need a pilot. At the moment and IF  they don't WE DON"T want it because we want to FLY don't we?   MAN & Machine not man riding in machine. Nev

Understand, but I have a 914 , that’s not about to change, I do like to fly it and have the engine run sweet  if that means doing a bit of tinkering I’m more than happy to do that, not sure why all the capitals 

[rhtrudder]

2 hours ago, RFguy said:

but he's  a rotax owner Don, when a set of rings for a rotax is $250, money is no object.  (I just bought 6 ring sets for a jab project for less than the cost of a single ring set for the rotax) .

Money is a bit of an object more so when I got charged $400 for the floats

[facthunter]

The CAPITALS are for emphasis. There's very few  there actually. I've flown some very complex engines  that are maintained by big organisations and am a long time engine builder and modifier but flying and keeping a good lookout needs to be the main game when you are airborne in an uncontrolled VFR environment. Where there's a choice the simpler design is the best, but I prefer fuel injection for better fuel distribution and less chance of icing and/or damaging high energy backfiring.    Everyone is free to make their own choice of course.  Some have limited budgets.   There can be a place for that type of involvement also.  Safety is always a prime consideration.  Nev

Edited December 1, 2022 by facthunter

[RFguy]

I think the up front purchase price for the rotax is good value for money. "The Rotax " is a good engine .

 

But the way spares are priced, the manufacturer does not encourage rebuilding/overhauling.

I see it as a method of ensuring a busy factory pumping out new engines. They dont want you to fix it. So the upfront buy engine cost is really not too bad since it should need much all the way to 2k TBP.

Oil filters and spark plugs and oil for "The Rotax" are cheap. that's all it should need over the 2000 hours.  

 

 

[Thruster88]

3 hours ago, RFguy said:

but he's  a rotax owner Don, when a set of rings for a rotax is $250, money is no object.  (I just bought 6 ring sets for a jab project for less than the cost of a single ring set for the rotax) .

Even though there are more Rotax 912's flying in oz than Jabiru's I am very sure less money was spent on Rotax rings in the last year. Have never seen a Rotax with less than 78/80 on a differential compression test.

[RFguy]

Jabirus are fine, just that the  jabiru engine doesnt have the capacity to absorb faults and abuse. 

- The engine should have the head + barrel pulled for inspection of leakdown < 70. That in my book is the maintenance trigger.

- the engine should be grounded for leakdown less than 65 for any cylinder.

- fit EGT sensors to all cylinders since again jabiru engine cant tolerate out of limits EGT. One sensor is not enough for this engine.  

- CHT < 160C.

there is a culture of ignoring the bad news by many concerned. 

 

 

Edited December 1, 2022 by RFguy

[BrendAn]

5 hours ago, RFguy said:

but he's  a rotax owner Don, when a set of rings for a rotax is $250, money is no object.  (I just bought 6 ring sets for a jab project for less than the cost of a single ring set for the rotax) .

are you still fitting the rotax in your jab

[RFguy]

yep

[BrendAn]

34 minutes ago, RFguy said:

yep

thats good.  told a few interested people to follow your posts on the conversion.

[turboplanner]

On 24/11/2022 at 10:02 AM, rhtrudder said:

Rough running engine between 4800/5200 , new throttle cables , Carbys done, balance good , runs fine either side of those revs, 

Needles, check manufacturer needle specification (needles come in many sizes and tapers), check manufacturer clip specification.

Bring it back to manufacturer specification.

Needles control the mixture from around 3/4 throttle for the transition to cruise/full throttle where the main jets do the controlling.

(Rotax may have the rpm for transition just to make sure this problem isn't on the main jets)

As others have said no need to do anything near the engine when you test for the rough spot.

Start engine on the manufacturer's needle specification and clip specification; if the engine is stumbling because it's over-rich, move the circlip one groove away from the point of the needle (which pushes it further into the jet). If still rough go another notch if there is one until you run out of notches. If that hasn't fixed the rough spot, go back to the manufacturer's groove +1 groove towards the sharp end like you did before, which is now leaning the 1/2 to 3/4 section of rpm. If that doesn't do it return to the manudacturer's grroves.  If it ran clean immediately before you fitted the new throttle cables, with a vernier gauge tail and the carbies off, check the slides are equal depth at idle, half throttle, 3/4 throttle (where the rough spot is) and if you can feel them hit WOT together (or if not, measure them just before the touch point). Sometimes with new cables one has a kink or is stiff and one slide pulls ahead or lags, and one could be getting on the main jet while the other is still using the slide cut.

Edited December 1, 2022 by turboplanner

[Yenn]

What’s this about notches in the needle. My Jab engine book mentions them, but they don’t have a notched needle nowadays. 

Why fit EGT to a Jab or a Rita’s. Neither have mixture control as standard.

[turboplanner]

2 hours ago, Yenn said:

What’s this about notches in the needle. My Jab engine book mentions them, but they don’t have a notched needle nowadays. 

Why fit EGT to a Jab or a Rita’s. Neither have mixture control as standard.

Well you can search on YouTube. Someone will know how to adjust them.

[RFguy]

So ! oxygen sensors....
They seem to be located on the headers where the cylinders combine.
some are exhaust heated (must get to min 350C, pref 500C)
most with more than 2 wires are internal heater type (a couple of amps at 12V) .

and wideband are 5 wire usually. has a current output and requires 2-5 V depending on the sensor + heater. 
I bought a wideband sensor from ebay. we'll see what it does eh ?
But if you want simple : use a narrow band sensor. IE you just get a "above stoich" and "below stoich" output. VERY simple to use with just a multimeter reading voltage.   and a 12V source for the heater. 
wideband sensor provides more 'linear' output  from rich to lean- but most cars just want to know if they need to go one way or the other.
Titanium sensors (rather than zirconia) more tolerant of crap in the gas. 

 

[rhtrudder]

2 hours ago, RFguy said:

So ! oxygen sensors....
They seem to be located on the headers where the cylinders combine.
some are exhaust heated (must get to min 350C, pref 500C)
most with more than 2 wires are internal heater type (a couple of amps at 12V) .

and wideband are 5 wire usually. has a current output and requires 2-5 V depending on the sensor + heater. 
I bought a wideband sensor from ebay. we'll see what it does eh ?
But if you want simple : use a narrow band sensor. IE you just get a "above stoich" and "below stoich" output. VERY simple to use with just a multimeter reading voltage.   and a 12V source for the heater. 
wideband sensor provides more 'linear' output  from rich to lean- but most cars just want to know if they need to go one way or the other.
Titanium sensors (rather than zirconia) more tolerant of crap in the gas. 

 

I ended up welding the plug at the start of the tail pipe where it leaves the muffler , leaves about 300mm to the end hopefully will get a good enough reading, 

[RFguy]

mmmmmm what does the street advice say on sensor location with  a turbocharger ?

[facthunter]

I know sensors "die" quicker when they are near the turbo. Nev

[Area-51]

Made up a FART box and tried it out last week; bloody great bit of kit; worth every penny 👍