how to Jab 2.2 Magneto

[myshed2]

My 2.2 has one failed magneto. Well having said that, the mag cant have failed altogether because the engine still runs when the good maggie is turned off however the engine loses lots of RPM. Almost no RPM loss with the other maggie turned off. Now I guess that this doesn't necessarily mean that its the magneto, just the electrical system on that side and could be, plugs, leads, magneto etc. Can someone with perhaps a similar problem give me some tips on trouble shooting this please. Where should I start.

[derekliston]

When it loses rpm is it still running smoothly? I would tend to think a plug wasn’t firing, or a lead is faulty, however if it is still smooth I’d be checking the gap between mag and flywheel. I had a similar problem a couple of years ago and ended up changing the distributor cap, the spring loaded carbon contact in the centre of the cap was not making proper contact. Also changed the relevant set of plug leads. Checked and set the gap between coil and flywheel. All been good since.

[facthunter]

If you start from cold and then run the engine quite slow (but above idle) with the good maggy OFF you will be able to determine the cylinder(s) not running by the fact they are colder . Mist a small amount of water onto the exhaust pipes near the heads. Nev

[Yenn]

I have had this problem and it was tracking in the distributor cap. Remove cap and it should be apparent, but clean it thoroughly anyway and see if problem solved. If so do the same to the other cap before it goes bad.

[440032]

I've owned a Jabiru 2200 since about 2001, and haven't found any magneto's on it.

How many hours have your Distributor caps and rotors done?

[derekliston]

I've owned a Jabiru 2200 since about 2001, and haven't found any magneto's on it.

How many hours have your Distributor caps and rotors done?

Just because it doesn’t have separate Bendix or Slick magnetos doesn’t mean it has none. The Jabiru system would commonly be referred to as ‘flywheel magnetos’ used to be common on motorcycle engines eg. Villiers and are still common on lawn mower engines eg. Briggs and Stratton. So maybe you need to look a bit harder or do some more reading! Nev, what say you on this???

[myshed2]

Thanks very much for your help guys. I think it is more than a plug (unless its two or three plugs!!) as the engine only just stays running with the good maggie turned off. I will start at the beginning and work my way through distributors, plug leads and plugs. I have checked the air gap between the flywheel and coil and they are OK.

I concede that the word magneto might be a bit of a misnomer 440032 but the high voltage is generated by magnets passing a coil so magneto is good enuff for me.

[Jabiru7252]

How easy is it to swap magnetos over? If the fault follows the magneto then the magneto is the fault. Shorted turns most likely Page 21, section 3.13 in the Engine Maintenance Manual (JEM0002-7) gives the resistance readings. Maybe running a good multi-meter over the coils to check them out. Just a thought. Good luck...

[Bruce Tuncks]

It's real easy to swap magnetos over. While doing this, check to see if there was any contacting which could explain the problem. A good tip is to use a black texta on the pole-pieces so that any contacting points will show up shiny.

Any contacting will put mechanical shock through the system. I reckon its better to have the average gap a bit bigger so the minimum gap is the ten thou. But my understanding is that with engines newer than mine, there was an extra machining operation to true up these gaps.

[facthunter]

Your air gaps relating to the magnet will affect the spark intensity and mostly when starting, if they are too large. Same with rotor and caps where you can lose some spark.

. The jabiru is a magneto set up resembling that most lawn mowers have in principle. There's nothing wrong with that as it's a self standing generator of high voltage sparks , needing NO external power supply. Coils can break down with time Heat oxidation and vibration and track internally and any rotors or caps likewise can track on a dirty surface or even worse a crack... I would only use wire leads and not "R" plugs as that puts extra load on the system and electricity always finds the path of least resistance which could be "inside" your coil. Nev

[Yenn]

I believe the coils are stock Honda manufactured.

If you do try swapping them over, be aware that they only work in one direction, so it may appear better to put one on the opposite way around to get the lead pointing in the best direction, but it will not work.

Go to the Jab maintenance manual for the correct procedure to test the coils.

You could put a timing light on to each individual plug lead to see if they are all firing. Try running the engine with the cowls off and plug leads exposed in a dark hangar, to check for arcing being visible. Best of all though is to just check everything from the coil, to distributor, plug leads, then plugs.

Whatever happens I reckon you will have to remove the distributor caps and they need a good checking for flashover or build up of conductive matter inside.

[facthunter]

The suggestion in post #3 works on all aero engines. or any other if the manifold has non siamesed ports or the engine has separate cylinders and heads, those parts can be used as indicators of whether the Particular cylinder is firing or not There are other ways of shorting out plugs etc but I don't like the idea of working on a running aero engine. It IS really dangerous. If you run with the cowl off don't overheat the engine.. Nev

[tillmanr]

I believe the coils are stock Honda manufactured.

If you do try swapping them over, be aware that they only work in one direction, so it may appear better to put one on the opposite way around to get the lead pointing in the best direction, but it will not work.

Go to the Jab maintenance manual for the correct procedure to test the coils.

You could put a timing light on to each individual plug lead to see if they are all firing. Try running the engine with the cowls off and plug leads exposed in a dark hangar, to check for arcing being visiblee. Best of all though is to just check everything from the coil, to distributor, plug leads, then plugs.

Whatever happens I reckon you will have to remove the distributor caps and they need a good checking for flashover or build up of conductive matter inside.

 

 

Please don’t run the engine in the hangar. Outside at night if necessary

[kgwilson]

The early coils were Honda and the later coils are Jabiru. I don't know who makes them though. Figure 44 of Jabiru maintenance manual JEM0002-7 shows the 2 types.

[facthunter]

There's no quality issue with the earlier (Honda) items it's just they didn't like the idea of them being used in an aircraft engine. (increased liability). Nev

[myshed2]

Weeeeeeeeeeeeeeeell. Thanks guys. Using the combined experience and wisdom of all the above to whom I am very grateful I did the following.

1. Established that it was the left hand electrical system that was faulty by taking all the plug leads off that side. Just to make sure that there was no shorting between leads etc.

2. Swapped all the plug leads (on the good side) with the plug leads from the bad side. Good side ran OK so it wasn't plug leads.

3. Ran the Coil lead from the good side to the distributor on the bad side and hooked up the plug leads (intake plugs only). Ran OK so it wasn't wither of the distributors. What's left......bleedin plugs and to cut a long story short it was the intake plug on number 4.

For all my swapping and changing things around I kept using #4 exhaust plug which ran fine. Lesson learned.

[kgwilson]

It is almost always something simple. I recently completed a 100 hourly & installed 12 new plugs as required. I started the engine and it ran like a Swiss watch. Test flight was great then after a couple of weeks managed a flight in between the rain events. On the shutdown mag check, No1 Mag (LH) the engine was rough. I suspected a HT lead but all are good. I ran out of time on Friday and on Monday I plan to swap Mag leads over & check. I suspect a plug so if correct, running on only No 2 (RH) mag (on No 1 plugs) the engine will now run rough, then I just need to do the same as you by replacing each of No1 Mag plugs 1 by 1 till I find it. If that't not it, it will likely be a distributor issue.

[myshed2]

Yeah kg you are right. The simple things. There is probably a comercial spark plug tester available but I am going to make one from an old car ignition coil. Will sure save a lot of plug lead pulling and engine starting to find a dud plug especially in your case with 12 of the mongrels.

Going by your photo I believe we have the same aeroplanes albeit yours has 6 more cyclinders. Sierra's rock.

Mine attached before it was registered 19-****

[kgwilson]

Yeah, 12 brand new plugs & 1 is a dud. Well I hope that is the case anyway. I remember your aircraft. I flew it on 13th of April 2011 with Garry Morgan before I bought my kit & decided on the 6 cylinder engine at the end of May that year. Garry's kit was really the supply of plans and materials but that meant it was a complete build from scratch not just assembly as most kits are these days. I spent over 4 years building but also built a hangar and made lots of house alterations in that time as well. I did everything including painting & I'd never spray painted anything before. Landing took a bit to master & I broke a prop. Now I can almost land it blindfold. I love mine and its excellent performance yet its stall speed

1 up is 32 knots full flap. Similar colour scheme too. The metallic blue Dulux FX paint cost $450.00 for the minimum 4 litres & I used less than half of it.

[kgwilson]

Got to my hangar by 9:45 this morning & it was stinking hot. Swapped the leads to have the Mags on different plugs & the crook side changed as expected. Good, Mags & leads are all OK. I then swapped plugs in order with a good (old) one that had performed flawlessly for 100 hours & did a check run each time. Murphys law was alive and well. I spent half the time wiping stinging salty sweat out of my eyes 6 effing times. Yep it was No 1 Mag, plug 6 that was the problem. New plug, all fixed, running like a Swiss watch again.

[myshed2]

Shees 4 years. You have done a magnificent job.

I concur with the landing difficulty. I learnt to fly on high wing aeroplanes and I could not get the hang of a low wing. Probably still leave a lot to be desired in the landing department and I leave the spats off not only so I can get the plane on its trailer but avoids leaving them strewn all over the strip. Where is your hangar?

Regards, Dave

[myshed2]

Beautiful.

[kgwilson]

YSGR, South Grafton. My problem was getting used to the sensitivity of the stabilator. I flew a PA28-181 Piper Archer for 20 years & the setup was the same. The difference is the weight and inertia. With the Piper it was just cruise in over the fence flare & let it settle. It just landed itself. Now I fly all the way to the ground reducing speed from about 55 over the fence to 40 about a foot off the tarmac, gently flare & it greases on. Well that's the plan but no 2 landings are the same.

Edited March 2, 2020 by kgwilson