Early rotax 912

[cjlesher]

Hello All, I'm and A&P with lycoming experience, and a flying RV7. I am new to the rotax world. I'm looking to purchase a 1991 kitfox model 3. It has a very early rotax 912 that has not been overhauled since new that I am are of. The plane has been sitting since about 2015, and has about 460 hours total time on it. I know that opinions will range from "run it as long as the compression and oil analysis look good" to "don't even think about touching it until its been overhauled. For what its worth the engine has perfect compression and a bore scope of the cylinders look good. I know this isn't the whole story though. What specific things would you be concerned with on an engine of this age? Crank? cam? gearbox? case fretting?

Given the idea of an overhaul, do any of the parts from an engine of this vintage have any core value?
The engine SN is 379(2?)738
Thanks in advance

Caleb

[avidflyer]

I was told by the head mechanic at Leading Edge Airfoils that these engines store quite well if kept in a dry place. Nicasil cylinders don't rust for one thing. JImChuk

[DesertFox4]

I owned a 1991 Model 3 with the early version 912 Rotax. Purchased it from the 2nd owner with 230 hours on it. Flew it for a little over 3 years and put over 1150 hours more on it. When I lost track of it after it’s sixth owner and near 2,000 hours, it was still going strong and had been untouched internally. If the engine you are considering has been properly maintained, 460 hours would not concern me barring any prop strike history. I’ve seen these engines sit as long as 8 years before first start and fire up as if they just came off the Rotax assembly line. Carbs may need cleaning or possibly rebuilding after sitting that long. Not a big project. Also all rubber hoses may need replacing per Rotax’s 5 year replacement recommendation. Those would be the cooling system hoses, oil hoses and fuel delivery hoses. Also not a difficult project.

Leading Edge Air Foils (L.E.A.F.), one of our site sponsors and mentioned by Avidflyer, or California Power Systems (CPS), another Rotax dealer and one of our site sponsors, could supply all the parts for carb rebuilds and or hose replacement if needed. Being an A&P, once you learn the proper care and feeding of that engine, it will likely be the most economical engine you’ve ever encountered.
Best of luck to you. Would like to know if you end up purchasing that or any other Kitfox. Welcome to TeamKitfox.com. Glad you found us.


P.S. The model 3 with a 912 80 hp Rotax is a formidable S.T.O.L. aircraft and loads of fun.

[jonstark]

Fly it like ya stole it! YeeHaw!

[michaega]

Make sure cases and crank are good. The Old none thru bolt cases are no longer readily available. Replacement comes only with cases, crank and cam. $$$$$$

[JamesD]

I am also an aircraft engineer here in Australia and have just brought a model 5 that was ground looped with a 2000 year make 100hp ULS. It has suffered two prop strikes and has 750ttsn. I have carried out the normal gearbox inspection, crank twist and run out with no issues. Mine is pre through bolt and coming from lyco/cons i was concerned about the case fretting. i have since learnt a lot about this and how to check it in accordance with the manual. I would recommend as stated, New hoses, rebuild carbs and maybe a quick gearbox inspection/clean then go flying! they are a tough little engine and with the right maintenance can well exceed their TBO especially the little 80hp

[napierm]

How did you carry out the inspection on the crankshaft? To do that you need to split and reassemble the case.

If you did so I'm interested in the procedure.

Thanks!


I am also an aircraft engineer here in Australia and have just brought a model 5 that was ground looped with a 2000 year make 100hp ULS. It has suffered two prop strikes and has 750ttsn. I have carried out the normal gearbox inspection, crank twist and run out with no issues. Mine is pre through bolt and coming from lyco/cons i was concerned about the case fretting. i have since learnt a lot about this and how to check it in accordance with the manual. I would recommend as stated, New hoses, rebuild carbs and maybe a quick gearbox inspection/clean then go flying! they are a tough little engine and with the right maintenance can well exceed their TBO especially the little 80hp

[JamesD]

The case does not require spitting for an inspection post prop strike. The procedures are in the manual and the crank inspection requires special rotax tools that include a protractor for the crank and then you then take each cylinder to TDC and measure the twist between all four. This is carried out due to rotax having pressed together cranks. I can attach the manual pages if you like. Also case fretting is a simple pull tq measurement both cold and hot. Both these inspections don’t take long.

[avidflyer]

Please attach the manual pages for the prop strike inspection. Thanks, JImChuk

[JamesD]

229822298322984 22985QUOTE=avidflyer;86686]Please attach the manual pages for the prop strike inspection. Thanks, JImChuk[/QUOTE]

Please keep in mind this if for an engine with an overload clutch and all my inspections where carried out with an approved rotax service Center. This in not all the pages required

[cjlesher]

Thank you all for the replies! I ended up purchasing the aircraft and am currently working through plenty of small items. Rubber replacement, adding a return line, some much needed panel an electrical work etc. Based on some of the hoses I removed, I don't think the rubber replacement has been done any time recently. I can't speak for the inside of the crankcase yet until it runs, but I was very pleased with the appearance of the cylinders in a bore scope inspection, as well as under the valve covers. Should have more details on this project in the next few months.

Caleb 23165