Gear set for Rotax 912 Engine

by Marcos Paulo Vigliassi in 912 / 914 Technical Questions 6 years ago

Hello

I have a motor 912 with serial number 4152411 and I need to change the two gears set but there are three P/Ns
866125
866517
866518

What would be the P/N for my engine?

thank you

Marcos

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Re: Gear set for Rotax 912 Engine

by RotaxOwner Admin » 6 years ago

RotaxOwner Admin

59 1.58k 13.9k

4152411 was produced way back on 14-July-1993 and the factory has no record of the original gear set used. The one you choose depends on which gear ratio you want... most usual is 2.43:1 - but there are wide and narrow variants...

Thank you said by: Marcos Paulo Vigliassi

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Re: Gear set for Rotax 912 Engine

by Marcos Paulo Vigliassi » 6 years ago

Marcos Paulo Vigliassi

1 4 0

Hello

Thanks for listening.

Would the 2.43 gear ratio below be compatible with my engine and could it be installed?

886517 GEAR SET I 2.43 narrow
886518 GEAR SET I 2.43 wide, 7 °

What would be the difference between narrow and wide options?

Best Regards

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Re: Gear set for Rotax 912 Engine

by Rob Seaton » 6 years ago

Rob Seaton

3 1.32k 240

The narrow 2.2727:1 is standard for the 912UL 81Hp.
You can install a narrow 2.43:1 p/n 886517. You will have to pitch your prop a little more as it will be going slower. You will have to be careful of detonation/overloading the engine (Use good fuel and stay above 5300 takeoff RPM).
No advantage to using the wide gears. Plus you would have to change the gearbox housing and the crankshaft.

Thank you said by: Marcos Paulo Vigliassi

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Re: Gear set for Rotax 912 Engine

by Marcos Paulo Vigliassi » 6 years ago

Marcos Paulo Vigliassi

1 4 0

OK, I understand that I can use reductions 2.27 or 2.43.

How can I know which gear is currently installed in my engine (narrow or wide) and the reduction?
Measurement, reference...

If I miss the purchase of narrow and wide it will not fit ...

Thanks!

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Re: Gear set for Rotax 912 Engine

by Bill Hertzel » 6 years ago

Bill Hertzel

13 1.95k 7.96k

What is the Gear Box Part Number? (Engraved on the Gear Housing)
8872xx and 996xxx are 2.27:1
8877xx and 888xxx are 2.43:1

The best way to guarantee what you have is to open it up and look at it.
Count the Teeth.
A 21 tooth gear driving a 51 tooth gear will give a 2.43:1 gear ratio. 51/21 = 2.43 ... and 50/22 = 2.27.

If it is a 912UL(80hp), it is almost certain to be a 2.27:1 Narrow

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

Thank you said by: Roger Lee, Marcos Paulo Vigliassi

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Gear set for Rotax 912 Engine

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