Vincent,
The biggest issue with inverted engines is priming. I mounted a foam ear plug on a bamboo skewer so that i could plug it into the venturi. That being said, if you completely plug the venturi and flip the prop, you draw fuel all right, but since the venturi is plugged, there is no airflow to pull the fuel up into the engine. That's why I try not to plug it completely, but leave a small air leak to get some fuel sucked up.

So the bottom line is that is hard to flood an inverted engine---gravity is working against you,

But in the end, I got pretty good at starting my inverted Brodak 40. So it can be done without a lot of problems.

Thanks Jim & Oliver

What I want to avoid is turning the plane over
while the engine is running, especially while
flying alone

Vincent

I've solo started several inverted engines (G.51 & 2Star .60bb), with very good results. It happened that I had Bruline air filters installed, and my proceedure was to choke either until there was some fuel on the filter, flip it a few times, feel for the bump and whack it or use the "electric finger". If it's on the dry side, I'll hit the starter and put my pinky over the muffler outlet (when running muffler pressure). That can work wonderfully...and it's a pretty subtle boost of fuel mixture. If flying solo, I think the starter is a fine idea for safety. I'm currently using a Kavan with the attached Ni-Cad pack...works well, with a wrap of electron tape around the starter cup.  Steve

As much as I dislike using electric starters, especially on engines without ball bearings, safety must trump tradition.......

So far, the electric starter has been needed only on the inverted ST 51.

Jim

I always start mine inverted but there's a trick to it. The trick of course is getting the fuel to run uphill. I cover the intake with a finger, pull the prop through a couple of times until I know fuel is getting through the spray bar and sitting on my finger. Then give a fast flick but roll my finger slightly off the intake to leave a small gap so air can rush through and sweep the fuel up through the crankshaft port. As with any engine you need to learn how many of these primes it likes for an instant start. Most engines are fairly forgiving on a slight overprime but my Irvine 40RLS only needs about half a drop too much and it'll try to take my finger off . The G51, VF's and Stalker are dead easy though.

Any tips for starting inverted engines ?
can it be done without priming , pre running,
burping etc , usually done with the engine
upright, difficult to hold without help
all so unnecessary with sidewinder or
upright engine installations.
I have built a large number of stunters
with side mount engines for this reason
no problems with those.
but the few I have with inverted engines
take a lot of extra trouble to start

any help ?

Vincent

   I find it easier to start them inverted than upright or sidewinder. It's all a matter of technique. For the first start of the day I "burp" the engine to clean out all the old oil and get it less gummy. Hold airplane inverted, no fuel in tank. I usually turn it until the intake is closed, and then dribble fuel in until the intake stack is full. Then flip it forwards a  few times, rotate the airplane around while rocking the prop to get the fuel into the cylinder, and to wash out the old oil. You can feel the engine loosen up. Last, hold it nose up and exhaust  down and rock it to get the excess fuel out. The engine should flip through with no problems - if it's locked, hold it exhaust down and rock some more to get out the excess. Then have the holder hold the airplane inverted , attach battery and back-bump until it starts and runs out the prime. Prime some more, do it again, prime again, start again, and then back-bump it a few more time to make sure the fuel is out of it. At this point the engine is warm, flushed completely, and mostly free of raw fuel.

   When it's time to fly, fuel the airplane, set it on its wheels, and pull the engine forward through compression 3-4 times, and then while flipping it forward, remove your finger. There's some timing to be done because you want to remove your finger in mid-flip. Continue flipping forwards a few more time and you will be able to hear and feel a little fuel sloshing around in the engine. This aerates the engine and gets the fuel/air mix in the engine just right. Then it's ready, attach the battery, and back-bump the engine and it will probably starts. You will have to experiment with how much choking you need to do on any particular engine, but most current engines will tolerate A LOT of choking and will start at just about any point short of being hydraulically locked up - as long as you don't try to start it by flipping forward! If you start with forward flipping it's much more critical about getting exactly the right conditions, and if it's slightly too rich it will kick back before you get to TDC and cut your finger, whack it, or something else bad. That's why you don't see many people flipping forward with current engines and props - they are just too dangerous to start that way.

    It takes a lot more time to write it down than it does to do it, and you will see virtually everyone at the Nationals doing the same thing.

    One caution - with almost any current high-quality motor, be prepared for it to start *at any point* that you have fuel present, battery or not. The piston/cylinder fits are so exceptional that they very frequently pop and start with no battery. My PA61 was notorious for that, even in 45 degree weather first time in the morning. And in the very hot weather at the 93 NATS, I gave up trying to choke the engine (stock 40VF)on the ground because it would start every single time. I would loosen it up before the flight, fuel it up, take it on the circle, and signal before any choking because it was going to start as soon as I touched the prop. I had that happen on very rare occasions on the ST46. But it's very much more common now than it used to be because the fits are so much better than they used to be. In particular, make sure your holder is holding on before *any* choking or aerating because it *will* start occasionally.

     Brett