Model number look up and rebuild kit?

Well, it looks like nobody wants to touch this one, so I will at least try.

I would normally tell you that the ADMIN will be along soon and try to give you the Engine Build info from the factory database, BUT ...
Although the 277 saw a number of Aircraft uses,  It was actually a repurposed Snowmobile Engine, and will likely Not be in the Aviation Database.

The truly bad news is that, almost 14 years ago, it was one of the first 2-stroke engines to be discontinued by Rotax.
You can find aftermarket parts to rebuild the Top End, but New Bottom End Parts are going to be very hard to come by.
Besides the scarcity, they will likely be expensive, but more importantly, they will be Old.
You might find a NOS (New Old Stock) Crankshaft, but it is going to have 14-year old seals on it that will need to be replaced.

- - -
The Model 582 is the only remaining 2-stroke in the Rotax lineup and it has been officially announced that it too will also be discontinued at the end of this year.  Get 'em while they last!

Indeed, 3404978 is not in the aviation engine database.

You might be able to get some limited information about it from this link: https://brp.com/en/forms/contact-us.html

Hello all

Well I am old enough to know a lot about the type 277.  it was indeed an engine that started life as a snowmobile power plant however the UL version was all aviation.  it had a Bosch point ignition and also a special exhaust for the powerband it was designed for.  The Bing carb was never used on any sled engines by Rotax, these were strictly for the aviation versions.  

There never was any rebuild or overhaul kit for this engine.  At 300 hours it was recommended to replace the crankshaft, piston and all gaskets as well as rebuild the carb.  The type 277 had an unusual angled intake socket to get the carb flat that was not used on any other applications.  (in the snowmobile the engine angled forward on the mount so the carb was flat with a straight socket.}  Most people simply flew them tell they quit for the most part.  Parts are almost non-existent as this engine has been out of production for decades.  The best is to check with some of the vintage UL aircraft people who still use them.  I know that the old manuals still can be had but actual parts would be difficult.  

Cheers