582 Misfiring

[Spurwing]

I have a 582 that has started to misfire at cruise speed - sometimes almost impossible to feel but if I watch the engine then it is possible to see a short vibration. At other times the miss is easy to feel while flying. Total engine time = 270 hours

All other temperatures etc are fine - egt in range - water temp in range althoughn the gauge is jumping around a bit running up and down by 3 to 4 degrees in quick succession. The engine sounds great all the time except on the isolated backfires that are very infrequent in relation to the misfires

I have done the following:
Changed plugs
Changed ignition cables - using a simple copper cable inside a rubber sheath as supplied by aviation engines
Checked as best I can all electrical connections
Changed plug connectors to the "new Rotax approved type.
Stripped the carbs and cleaned everything and blown out all jets - jets are relatively new (65 hours)
Changed the fuel

After doing this I thought it was fixed and only after about 20 minutes flying picked up the first "miss" again.

Now it is missing at high revs on a ground engine run up whereas after changing the items above and before the flight I it ran perfectly on 3 extended ground runs at 6400 revs.

Can anyone help please.

[Boet]

This engine is trying to tell you something that you will probably not like to hear: IE= A LOUD SILENCE Is it autolube or premix?
Take the flywheel off and remove the stator ring. Have someone with the nessecary testing exuipment check it properly. You might have a loose or a bad solder joint somewhere. Take the exhaust manifold off and check the condition af the piston rings through the exhaust ports. A misfire is a sure-fire way of tour engine of telling you that soon there will be NO fire

[Duck Rogers]

I'm with Boet on this one. It also sounds (no pun intended) like electrical to me, especially after what you have changed/cleaned already

[John Boucher]

Check the wires from the stator to the coils... especially where they enter the Ducati connectors either side!!!
They can be "dis" or burnt off inside yet you'll still get spark - the more it goes on the worse the problem becomes!

Just my bit for safety....

[Spurwing]

Hi Guys

Thanks for the advice - one thing I forgot to mention is that if I switch off either of the mags the missing gets worse - and stays about equally bad regardless of which mag is off. Once both are back on again then it improves - tells me that if it is electronic it must be related to the common electronic system ie coil.

Do I need special tools to get to it?

[John Boucher]

That be electric me thinks.... Sounds like the Stator coil.... The boffins like Duckie & Morph to the rescue please!

In my aircraft, I have to remove the whole bloody engine to get to it! the only advantage I have then is to do the engine mount rubbers over!

[Spurwing]

Me again - thanks for the advice.

Removed the magneto and foungd that the stator coil was loose - the two bolts holding the stator bracket were loose and consequently coil was loosed and not properly earthed - had I carried on flying the whole coil could have become completely loose and jammed into the magneto - definate engine out and expensive repair.

The engine was telling me something - very glad I listened!!

[John Boucher]

That's what so great about our forum....

Pleased you found and repaired the fault!

[Duck Rogers]

And the winner is...................







Boetie Blommetjies !!!
There is no substitute for experience.

[Morph]

CLU-less had a problem a few weeks ago when suddenly the one ignition system failed. He only noticed this at the next mag check.

When he pulled the flywheel off he noticed some of the plates from the top of each coil had come loose. It probably started with just one, but that one created a lot of damage on the other coils, removing some of their plates as well. The second ignition system was barely making contact

[German]

Could these "loose things" be because of normal 2 stroke vibration or anything else?

[Boet]

THAT, Sire, is just the nature of the beast.