Mag check rpm drop -912 Extra

[Papillon]

Hi Guys

Please can you techno-whizz guys out there able to point me in the right direction? Calling on the boffins ie the likes of Duck or Morph if still around!

I get an rpm drop of about 500rpm on one mag when doing a mag check at around 3000rpm and even more at higher rpm. I've had our AP check out all electric components (pick ups, cdi, coils, plugs and HT leads) and all appears ok but the rpm drop persists . We have also done the test found in the Rotax Owners Assistance Network (ROAN) manual to determine whether the problem is carbs or electrical and the results confirmed it to be electrical. The carbs have also recently been balanced.

Could it be a symptom of the 912 Extra having the higher compression pistons which would then require different plugs? The AP wants me now to test 914 plugs to see if the problem persists. Does anyone know what changing the plugs will do & should I rather try the 100HP plugs first? Otherwise any other help or advice would be seriously appreciated ..........

[JvTonder]

I have the 912ULX and use the 100hp plugs(DCPR8E) very little RPM drop and same on both sides.

[Papillon]

Hi JvT

Thanks. Have you ever used the 80HP plugs and if so, was your mag check normal?

Am just trying to establish whether I actually have an electrical problem or if I'm using the wrong plugs?

[JvTonder]

Hi JvT

Thanks. Have you ever used the 80HP plugs and if so, was your mag check normal?

Am just trying to establish whether I actually have an electrical problem or if I'm using the wrong plugs?

Hi Papillon,

Sorry but have only used the 100hp plugs, they are not that expensive go buy some and see what it does, about R60 buks at my motorcycle shop.

Cheers.

PS: Spoke to my AP and he said you must use 100hp plugs in the extra.

[Papillon]

Hi JvT

Thanks a lot. I got a chance to get to the hangar and checked the plugs. They are the 100HP plugs (DCPR8E)

So back to square 1 again with no clue as to what to even check next!

[JvTonder]

Hi JvT

Thanks a lot. I got a chance to get to the hangar and checked the plugs. They are the 100HP plugs (DCPR8E)

So back to square 1 again with no clue as to what to even check next!

Sorry to hear, I have no idea what the cause could be. Maybe you should contact Niren at Rotax and ask his advice. Do know that a while (read long time) ago a mod came out on the stator coils. Depending on the age off your motor that might be something to look at.

Might also be worth it to go to the Rotax website and use your motor serial number to see exactly what all the SB and AD is that must be complied with, just a thought!

Good luck and let us know when you find the problem.