This is Jorge from Spain (writing from Africa). I have an ongoing problem with my engine, a rotax 912 80hp. I hope any of you guys could bring me some light.
The engine has little hours, 190hrs, but it was standing on the ground for some years. I inspected the engine trough but after some flying one could feel a vibration wich became stronger with the hours.
After discarting other factors, it became obvious the problem was comming from the ignition. The accessible part of the system was checked by a mechanic (I have no clue about electricity), conexions, cables, etc and the ignition boxes cross connected showing a problem on the back part (stator, charging/trigger coils ...).
At the same time, being the carburators throughly rigged, synchronized and inspected, the spark plugs on cylinders 1 & 3 (that is right side cylinders feed by right carburetor) were showing a notorious difference on color.
#1 totally white #3 totally black ... Will try to post some pics.
Because of the work, I didn't had the time for further investigation but I want to get ready for the next round so I know where to aim when I arrive home!
So my question is, did any of you had problems with this part of the ignition system? Is it like a weak point on the engine or well known rotax problem there?
Do you think the spark plugs problem is related to the ignition or I do have two different troubles here?
Your help is highly appreciated!
Thanks in advance,
Jorge
There is a lot of great info on this board. I fought the same problem you are having last year- best advice I can give you is more than likely it is still in your carbs vs. your ignition. I would go back and verify that your intake manifolds are not leaking anywhere, check and make sure the needles and seats are good- pilot jets and venturis are clean, diaphragms don't have any rips or tears and move smoothly, etc. in my limited experience usually ignitions work or they don't. With such low hours on it that means it's been sitting a lot- and carbs are more than likely the problem.
From what I am seeing of your plugs that is a normal indication when you throw fresh plugs in and fire it up, mess with the carbs, shut it down, mess with carbs, fire it up, sync, shut it down- you get the idea. If it is only one cylinder and you are sure it's not the carbs you can switch coils around and see if the fouling moves to a different cylinders- than it would indicate a bad coil.
the intake route was inspected and the old rubbers and seals replaced with new ones. Needles, seats and jets ... All new.
Actually it also happens on the other side ( cylinders 2 & 4) but it's less accentuated.
The spark plugs in the pic were running for about 5 hrs indeed, but the previous set I was running had the same colors.
Now you mentioned ... The diaphragms were not new but in good shape (flexible, no rips) it might be worthy to double check. Then I will start to play with the coils and see if that helps!
Rotax 80hp, ignition problems
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Re: Rotax 80hp, ignition problems
