Rotax and Fuel

[Pooch]

Guys, do the Rotax engines use 100LL or auto fuel?
Different for the 582 and 912, I would think, right?
And if you are using car gas, what do you do when flying away from home? How do you make a fuel stop, somewhere?
Wondering if I should stay away from engines that need you to run to the nearest car gas station with a couple of five gallon gas cans, to top off the tanks.
Thanks.

[DesertFox4]

All 912 series Rotax & 914 turbo engines are made to run on 92 octane or better autofuel (unleaded). Will run on 100LL Av-gas if you need to. If running all 100LL you must use a semi-synthetic oil. 100 percent synthetic oils will not work with 100LL. Also if running 100LL you should use the fuel additive that Kitfox Aircraft sells. It's added to the fuel to keep lead deposits down in the engine. 100LL use also requires more frequent oil changes. 25 to 30 hours is normal on 100LL oil changes.
I run 100 % 100LL Av-gas using the fuel additive on every fill up. No problems after 700 plus hours. My fuel tanks do not like alcohol laced auto fuel or I'd use it more even though it's a pain with gas cans and all.
Also I don't think our fancy airport likes self-fuelers anymore.
I like the 100LL for convenience on cross country flights and the safety during high altitude flights. Now if they would just take out the lead I'd really be happy.
Can't address the 2 strokes needs. Lots of members here have much knowledge of the 2 stroke engines and will reply.

Lots of posts in the archives about this and just about any other topic you can think of. Use the "Search" feature to see what has been discussed.

[Av8r3400]

The 80 hp 912 UL motor is actually intended to run on 87 octane auto fuel.

The 2-strokes are also meant to run auto fuel, but those need 92 minimum octane (I think).

Rotax has stated that up to 10% ethanol is acceptable.

There is a potential that the ethanol can damage the fiberglass the fuel tanks are made of. There is a possibility that the fiberglass can break down and clog filters and potentially cause engine damage. Yet, some people have run the ethanol fuel for thousands of hours without incident. I personally have not seen any damage to tanks, only anecdotal stories.

However, I will not use ethanol blended gasoline in my planes. Rather safe than sorry.

[DesertFox4]

I personally have not seen any damage to tanks, only anecdotal stories.

I have first hand knowledge. My tanks broke down after two tanks of 10%alcohol auto fuel. Actually it was just my right tank as I sloshed the left tank with alcohol resistant slosh shortly after first flight due to a small pinhole leak. Made the mistake of leaving half full tanks for 4 days and not flying. Next engine start the resins "fogged" both carbs killing the engine before I could even taxi away from my hangar. It happened that quickly thank goodness and not during take off or flight. Took 3 hours per carb. 6 cans of carb cleaner, several assorted brass wire brushes to clean the sticky brown residue out of all the little journals then I ordered 2 rebuild kits from Lockwood and rebuilt both carbs. The fuel I poored out of the carb bowls was milky brown. Replaced my fuel lines and filters. Fuel pump seemed unaffected and sticky residue did not get past the carbs and into the manifolds.
Thought I was going to have to buy two new carbs. but got them back from the brink. Drained the remaining "fuel" out of my Kitfox. Rinsed with 100LL and have had no leaks or further degradation.
Guess what you'll never find in my aircraft again? Have several friends that fly a lot of auto gas and have never had a problem. Go figure. My luck I quess.

[Dorsal]

Steve,
What generation are your tanks if I might ask?

[DesertFox4]

Guessing 1992-1996 vintage. Not really positive as I bought a set of wings through a friend from a project that had been sitting for a while. The alcohol problem may be hit and miss as I know owners that have tanks from all time periods and have not had the same problem I had. Maybe different "runs" were more resistant than others. Not sure. Not a glass expert. Just know that it can and has happened to me. If I ever have to recover my wings I'll be buying the new resistant tanks from John.

[Caballo]

I purchased and began building my Mod.III in 1991. Then due to many issues, I wrapped and hung the aricraft in the barn until this week. From the sounds of things, I should consider purchasing new style 13 gallon fiberglass wing tanks in lieu of installing the ones I purchased with my kit (ethanol was not used in 1991)?
I have been looking through the service bulletins and also noticed I will be purchasing numerous other components that have been identified as inferrior over the years. One that surprised me was the replacement of the reduction gearbox housing.
Any comments or pointers are welcome to help me get back up to speed with my project. Thanks - Mark

[cap01]

mark , absolutely , replace the tanks , especially if the wings arent covered . my model IV kit is from around 1993 and has both 6 gal tanks installed which in reality one side holds 5.0 gal and the other side 4.8 gal . besides the alki problem , i couldnt carry enough gas for my purposes . i have a wing off installilng a 13 gal tank now .
there are some good epoxy tank sealers but no one will step up to the plate and say thats the way to go . i did slosh my tanks with some but whos to say how good of a coverage you can get espically when the tanks are already installed in the wings .
good luck

[Slyfox]

so how is the replacement of the tank going?

[cap01]

the old tank is removed , the rib and brace are removed . i have to fabricate some fittings for the brace with the correct angles for the shortened brace . it appears ill be able to remove only the fabric on the top of the wing and one bay outboard of the end of the tank . i had a little problem with the new tank and had to send it back to kitfox , i hope to have it back this week . i might add the excellant support i received from john and debra resolving the issue .