mike98624

I just finished building my Venus 40, and put a new 46FX in it. I ran two tanks on the bench, then put it in the plane. I mounted it inverted per the instructions for the Venus. The engine refuses to start unless I turn the plane over on its back or up on a wingtip. Also, I can't make it rev well on the ground or at low speeds. It will idle just fine for a while, but then whenever I try to rev it up, it quits out. This happens often on takeoff, and once when I wanted to flare a spot-landing. Luckily I was able to land it normally, but I would rather it not quit on me during flight. I don't tend to think of deadsticks as fun, especially with a new plane. I have been told that the problem here is that the tank is too high in comparison to the centerline of the carb. I don't want to cut into the stuctural elements of the plane, so does anyone have any other ideas for how to fix this problem?

DMcQuinn

My Feedback: (13)

Make sure both needle valve settings are exactly right before you make any more dramatic changes. Turn the plane upside down (so the cylinder is pointing up) and start the engine. Rev the engine a few times to full throttle and back to idle. Let it idle for 5 seconds. Now, still at idle, pinch the fuel line closed and see how long it takes before the engine speeds up and quits. My guess is that you are too rich on the low speed needle valve (most new engines ship with the low speed set too rich in my experience). At idle the engine should speed up and then quit after a few seconds. If it runs for many seconds before speeding up and quitting, then it is too rich. If it quits immediately after you pinch the fuel line and never speeds up at all, then it is too lean.
Also, try to get a few more flights on the engine before you give up. New engines never run as well as ones broken in. Yours is not fully broken yet. When the needle valves are both set correctly, the engine will run OK upside down. Even then, it is sometimes easier to get them started with the plane upside down.
And, yes, the tank should be more or less even with the carburetor, but I doubt this is your main problem.

MHall

My Feedback: (7)

You said that the kit is set up for an inverted engine and that tank is set up per the directions?? I agree that it sounds like the tank is set too high for the engine to handle. Have you been able to get the engine to run up to full rpm while installed in the plane? You said that running the engine with the plane inverted it runs normal, that sounds like the tank is too high. I have not owned that plane, lets see if anybody else has dealt with it. [8D]

mike98624

Thanks guys. My basic instinct is just to fly it for a while and see if it gets better, but I will definitely try that test with the fuel line.

Mike

Fly-guy

First of all an inverted 2 stroke wil send the most hardened and experienced modelers MAD. if you don't believe me just bring one to our field and wait for the laughs when the thing won't run. Well now that i say that there is a guy at our club who has a one in a million motor a 46FX that runs like a dream inverted. your best bet is to tune it with the plane on its wingtip, it is almost inverted but not quite and I'll speak form experience if you tune it right way up(the motor that is) as soon as you turn it over it will drop rpm and most likely die. Also DMcquinn said that it is probably to rich at the bottom end, he is most likely right so try that as well.

But if you want to save yourself some tuning time and get in more flying, put the motor in sideways or pointing 45degrees down, either way it wont mess up your cowl and will run better.

Fly-guy

mike98624

It was too windy to fly today, so I just ran it up outside my house. It seems to be running much better now. It starts easily with the plane right-side-up, with the throttle at idle (I use a fast idle). It was faltering a little when I would rev it quickly past half throttle, and the muffler was spitting a lot. So I leaned it out a few clicks, and it revs great now. Still rich enough for a new engine (I think) and running pretty well now. Thanks for all the help, guys. I guess I'll see how it flies next time. Hopefully I will be able to get some air tme on it tommorow.

Mike

WMB

My Feedback: (1)

Mike, did you get that engine running OK? I took my Venus for maiden today and couldn't get it running right unless I flipped the plane upside down. But once the engine went inverted it would die. How do like the Venus?
Mike