I have a 45 I'm trying to run inverted in a Zen. With the engine inverted, the carb is well below the fuel tank. I can't change that.

I think the engine is flooding because the fuel is siphoning out the tank. If I start the engine with the plane inverted, will it run OK in the air?

Thanks

I just use Hemostats (Medical pliers or any similar) to clamp the hose while fueling, then remove them right as I am ready to start the engine--- Otherwise it will flood...Once running it should be fine...

You running a pipe or stock muffler? I had the Zen with a YS-63FZ then a Tower-75 then a Rossi-60 - great flying airplane!

Now that's an idea. I'll give it a try. BTW, it's piped. And I really want to get it in the air. I just can't find the time.

Thanks

Is it a Macs 7.5CC or 8.5CC?

The YS-45 is a BEAST (as you probably already know) on a pipe! Pinching the line is a hassle, especially if the stuff is under the cowl--

Another trick I use on my F-90/ OS-160FX combo is to close the needle valve when filling to avoid flooded-ness [X(] Would work probably on the YS also right up until you start- Just remember that setting!

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If I understand what you are saying properly, your YS is not functioning as it should. No fuel should flow until the engine places a demand (vacuum) upon the regulator circuitry (that thing below/above the carb that most folks call a pump - it isn't). The fact that it can flood proves that it is not working properly. Running this engine inverted is a piece of cake, when all is right. It cannot siphon fuel when the regulator circuitry is working properly.

Usually, a diaphragm replacement and diddling around with the valve and spring will restore things to normal operating order. Don't give up. This engine will do what you want it to do - in spades.

Artisan-

Thanks for the info. This makes sense to me. I did run the engne on the ground few times last month. I don't recall any problem back then. So maybe something did go wrong.

Where would I get parts if I needed them. And do you know of a faq or a source of info on this engine?

Thanks again

They run fine inverted, tank location isn't important within reason bacause the system is pressurized. Don't have any 45's now, but had a pair a few years ago... yes they are a beast. One would think the regulator should keep fuel from siphoning when the engine is off or at idle. However, one thing I do remember about both my 45's is they tended to "leak" fuel out of the carb when off if tank pressure wasn't released. Not sure why, both did it from day one and ran great. But you might check the regulator anyway if you are having problems... might have a bad diaphram or some gunk in there on the seat. None of my YS 4strokes leak when off, it was only the 45's. My sugegstion would be to always release tank pressure after a flight.

If you should need parts for the 45, try calling Central Hobbies. www.centralhobbies.com They have been my best source for YS parts. If they don't stock YS45 parts, they could probably point you in the right direction. You can also go direct to YS, at www.ysperformance.com