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Tecnam P92JS Heavy Duty Starter Motor


eloigorri
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Hi forum.

 

I have just bought a used (250 hr) 2004 P92JS based in Northern Thailand.

 

A fellow enthusiast at my club recommends I replace the standard starter motor with the heavy duty version after he saw it struggling to start one day (prop kick back etc). He is a qualified Rotax engineer and says that where possible on the 100hp Rotax he is involved with, he always does this if its physically possible as it saves the life of the "Sprag Clutch" and will help start the engine quicker.

 

I have checked the way the standard starter has been mounted on my 92, and providing the replacement is not wider than by 25mm it looks like a pretty straightforward swap in/out job.

 

Has anyone here done this, and if so with what result? Is the FIAMM battery good enough to work with this heavy duty starter motor?

 

I understand that current models of the 912 ship with the bigger starter motor now.

 

Many thanks for any advice.

 

 

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Guest bateo

G'day There,

 

Firstly, I would put in a Heavy duty starter motor straight away, especially if the engine is starting to Kick back on start.. The Sprag Clutch will damage very quickly with a poor crank.. (Standard starter motor).

 

Unfortunately I have experienced Sprag Clutch Problems on my 912 with only 650 hrs on the clock (meant to be changed on overhaul).

 

It cost me over $800 in parts/labour with me doing most of the work!!

 

A new heavy duty starter motor will cost you around $900 but makes an incredible difference and will save you internal damage to the Sprag clutch and circlip, which can shatter flilings through the engine if not attended to immediately. This starter motor should fit right in (sticks out more than the standard), it has to be fitted in a way where it does not meet with the airframe/engine brackets.

 

Finally to a battery, With a standard starter motor- a FIAMM is ok but having said that.. A FIAMM was being used in mine when the Sprag clutch was damaged.. (Poor Cranking and standard stater motor).

 

I would suggest a Odyssey Battery, They are a bit more expensive but have a strong amperage to crank the heavier starter over.. They are the same size as a FIAMM although you will have to construct a slightly larger bracket to fit around it.Most Jab's and all Tecnam's I have come across now run this battery here in AU...

 

I have experienced every problem just mentioned and now the P92 has no kick back at start or shut-off, fires straight away at first crank , no vibration of the airframe and runs much smoother at idle and max rpm.

 

It may cost you a little bit up-front, but I could imagine everything in Thailand being cheaper there then here anyway....

 

Let me know if you have any questions as I did all this myself

 

 

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Hi, many thanks for the quick reply. This confirms what I have been told here.

 

Sadly GA in Thailand is not very developed, less than 100 private a/c regsitered here, so getting parts normally involves getting them shipped from the US, or you neck of the woods!

 

I will go ahead and source the starter motor.

 

I currently have one of the exhaust down pipes near the side of the

 

existing starter motor with approx 25mm space between them. If the heavy duty starter is a lot wider, I may not be able to fit it. I have no obstacles behind the starter motor so length is not really an issue.

 

If the heavy duty version is very close to the exhaust pipe, I did

 

consider putting some heat shielding round it.

 

What do you think?

 

 

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Guest bateo

G'day,

 

You Shouldnt need to put a shield around it.. The exhaust must be a bit different design to my P92.. But the Heavy duty starter is no wider as it much fit in the same area as the standard.. Its much longer.. You shouldnt have to worry about width..

 

 

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Guest bateo

Paul, A standard is small and stumpy.. When I say small.. Probably 5-10 cm in length.. (Mostly black in colour)

 

The larger starter is around 15-20 cm in Length for memory.. If your still confused or not sure.. insert a photo and I'll tell you.. But I am sure you'd get a fair idea at just looking at it's length... Paul if you are having electrical starter problems and only have the standard starter.. I would spend that extra $$ and buy a heavy duty one anyway!!! It will save you $$ and time in the long run.. and you will notice the difference especially with the Oddyssey battery.

 

 

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Guest bateo
Hi, many thanks for the quick reply. This confirms what I have been told here.Sadly GA in Thailand is not very developed, less than 100 private a/c regsitered here, so getting parts normally involves getting them shipped from the US, or you neck of the woods!

 

I would of Thought you would pick a new odyssey battery up much cheaper in Thailand as that is where they come from??? I'd say it'd be cheaper than over $300 AU surely???? Dont think you'll have much trouble trying to find a starter.. I would just make an enquiry on AU and US companies and compare the cheaper alternative..

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Apparently I have the heavy duty starter - I also have an Odyssey Battery.

 

We removed and stripped back today, and discovered the likely cause of our fuse blowing on start. Inside of the housing was contaminated from some seeped white spirit from a recent clean - it had also collected a bit of grease and dirt and looks like it was the cause of some poor electrical contact.

 

It cranks ok now, but we haven't had it out of the hangar for an engine run as yet.

 

Battery life actually was ok after all.

 

 

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Guest bateo

I could not find any torque settings for the M5 bolts or flywheel bolt when the Sprag clutch was replaced.. They were not written anywhere in the manual.. It took quite a bit of research to find the exact torque which to me, were too high aswell

 

 

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The 912 starter motor has 5mm studs (I think) and the nuts should be torqued to 6N-m (about 55in-lbs or 4.5ft-lbs).

 

The flywheel bolt is M16 and should be torqued to 120N-m (about 88ft-lbs).

 

Is that what you have?

 

Bruce

 

 

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Guest bateo

I cant remember them off the top of my head but I remember the M16 being 120 Nm.. I may have to look at the M5's though?? Maybe they might differ from the Torque mentioned..?(Thought it was a bit higher) I cant see any damage being done, 100 hourly is due in few hours anway which I will clock up coming home From Armidale on Friday...

 

 

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  • 2 weeks later...
  • 1 month later...
Guest pelorus32

Hi David,

 

great to see you back again. Slip up to Shepparton one Saturday for lunch.

 

Regards

 

Mike

 

 

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  • 2 weeks later...

Heavy Duty Starter fitted

 

Just to let you know, I have now fitted the heavy duty starter and as suggested, it has made a big difference.

 

It was a pig to fit, due to the limted space. Had to dismantle the airbox and release the carbs to get access to the bolts. While I was there I also replaced the carb flange rubbers which had been overtightened on my plane by the prev owner. 049_sad.gif.af5e5c0993af131d9c5bfe880fbbc2a0.gif I fitted the updated ones with the spacer to prevent overtightning.

 

Miss Dippy is back together, and from my initial first starts, a much happier and healthier starter!

 

Thanks for all the advice.

 

 

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