914 Barely Starts and Won't Get Above 780RPM (Video)

I agree about staying away from Avgas. I use Mona’s with 10% ethanol to 10K altitude and live in Arizona with daytime temps to 105F+. Tons of LSA here and for the most part none of us have any issues. The Flight Design aircraft community mostly uses Mogas with ethanol with no issues. I have friends with 3K - 4K hours on their engines without any issues because they use Mogas. Proper engine air flow can make a big difference and unfortunately not all aircraft companies do well with this.  Yes we take our Mogas out to the airport and it far out weighs the issues that using Avgas will produce later on.

Sean Griffin wrote:

Jeff -

I would dispute "the decision to use or not to use Decalin with Avgas is less clear with a turbo charged engine" 

on the basis that Rotax have consistently, over a long period, recommend against the use of AvGas - the use or not, of Decalin does not change this.

Further; this Forum sees lead (AvGas) related contamination of engine/gearbox questions, on at least a monthly rate, if not weekly. This suggests to me that the routine use of AvGas in Rotax 9 engines is far from being a trouble free decision, even with the use of Decalin. 

The decision to use AvGas will significantly increase (x2?) the service/maintenance cost of your Rotax 9. Decalin will just further add to this cost, as will the higher, than ULP, cost of AvGas.

This is now a very old debate - all points for/against (AvGas/ULP) are well known (by most). It is now in the realm of personal preference - I would liken it to smoking, with its known health/financial/social costs verses non smoking - your choice, please don't smoke in an enclosed space with me.

Sean,

We are actually in agreement, and my post was meant in favor of using unleaded fuel.  I go to great lengths to use Mogas. What I meant was that when you have to use leaded fuel - say on a trip where only leaded fuel is available - Decalin may not be a net benefit if your engine is turbocharged. 

Decalin may have a caution about turbochargers, but Rotax itself recommends it for all their 9 Series engines, including the 914 and 915...  I'll go with Rotax on this and continue my usage of 100LL.

Craig - semantics perhaps but I would interpret your Rotax quote as more of an observation, nothing as strong/affirming as a recommendation.

Yes, it's not technically a "recommendation", but I'll still take their probably extensive database based on specific field experience with Decalin which says no detrimental effects over Decalin's generic warning.