Gear Ratio

[Kurt.A]

Do any of you have a sure fire way of telling what gear ratio is in a 912UL? I see that they could have come as 2.27 or optional 2.43. From what I can see so far I could turn the prop and count crank revs VS prop revs or pull the gear box down and count teeth. Is there an easy way to count eng revolutions? I have minimal space between the firewall and the eng and can't see the crank.

[mr bill]

You could pull a spark pug and watch the piston.

[Av8r3400]

If you have an unmodified 80 hp 912 UL, you have the 2.27 gear set.

The 2.43 came on the 100 hp and 914 turbo engines.

[Av8r3400]

Another way is to input your serial number into Rotax Owners and it will spit out all of the relevant data.

[Kurt.A]

The log book makes no mention of any mod's done to the gearbox. However, with the extras that came with the plane I have a few new gear box parts and pictures of the gear box being apart. Not sure if the pics and parts are from this eng. I am suspecting that it will be 2.27 but to be sure I will have to do the rotation method by pulling a plug and see what I come up with.

[Av8r3400]

Why are you wondering? Just curiosity?

[Kurt.A]

Why are you wondering? Just curiosity?

Going to be ordering a prop soon and just want to have all my facts straight

[Av8r3400]

The 1 and only 80'hp I have ever seen with a 2.43 belongs to a friend. The only reason it has that ratio is because it started from the factory as a 914.

How many hours are on the engine? If it has 2-300 you may be well ahead of the game to pull the gearbox anyway and have it re shimmed. It's not a hard thing to do yourself if you have a press.

[Kurt.A]

The 1 and only 80'hp I have ever seen with a 2.43 belongs to a friend. The only reason it has that ratio is because it started from the factory as a 914.

How many hours are on the engine? If it has 2-300 you may be well ahead of the game to pull the gearbox anyway and have it re shimmed. It's not a hard thing to do yourself if you have a press.

There is 750 hrs on the eng. I had a read through the gearbox shim procedure and it looks very easy to do. I do not have a press but have access to several at customers shops. Time to get some shims ordered up. I do not see any with the other gear box goodies that came with the plane