KrashTestKev

I have GP U-Can-Do 60, with an Evolution 100. This engine mounts upside down on this plane. The carb sets slightly lower than the tank, which is why i suppose that the carb always drips fuel while not running. Well I cannot start the engine with the plane right side up on the landing gear. I used to be able to though, I can't remember if i changed glow plugs or prop size...but now it will not start unless I turn the plane upside down, which makes engine glowplug side up. Starting it this way it fires up right away but when i turn it back over and put it on the ground for take-off ...it dies, everytime!!!!! If is start it upside down and put it at full throttle and then set it down for take off...and leave it at full throttle and just let it rip..it flies just fine. I don't get it.

Why did it used to start with plane rightside up/engine upside down and now it doesnt?
Do I need a hotterglow plug? Or one with an idle bar? (i dont know what type was in this plane before as i bought it used)
Could it be my glow stick? I've put brand new batteries in it several times with no different result.
HELP!!!!!!!!!!!!!!!!!
What should i do?

-kev

TedMo

Will attempt to give you some ideas. As you have said it drips fuel through carb when not running and that your tank is higher than it should be. That's probably your problem right there, it's siphoning; lower tank. If that's not possible then remove the restrictors from carb thereby allowing further adjustment of both the high and low speed needles. I believe your low speed is set too rich due to tank height. I don't have same plane but do have the 46 size with a 4 stroke 82 and it runs fine. I also have a 46 Evo but did remove resrictors to properly get it tuned.. Yes an idle bar plug may help as well since you appear to be drowning the plug during start up.

combatpigg

My Feedback: (3)

I would get the engine tuned right side up if all other efforts fail. Even if it means getting it dialed in on a stand. Once you're happy with it, then set it up inverted with a high tank to see how much leaner it needs to be set.
Get a tool to clamp the fuel line, it will make life easier.

proptop

My Feedback: (8)

This seems to be a consistant problem with this airplane...
We've had a few of them in our clubs...
The tank in too high in relation to the carb, so you need to take special precautions regarding carb adjustment.
It sounds like you need to lean the low speed mixture adj. some more...and a hot plug will help. (The H9 Super Plug or an O.S. type F or maybe McCoy MC59 )

One of my friends had a UCD 60 with an O.S. .91FX in it (at first ) and had problems...
He got tired of fiddling with it, and when he decided he needed more power, he installed a 1.20AX and side mounted it (cylinder 90 degrees from original inverted position, or 9 o'clock when viewed from in front )

da Rock

move the tank
side mount the engine
adjust the low speed needle

billd76

My Feedback: (3)

I have a tucano with an inverted engine. Always have to start it upside down. With the carb lower than the tank, the cylinder is getting filled with fuel, causing it to lock. I assume it wont even turn when trying to start it? It does make it a bit of a pain to start, but is just one more step in the start process. Once mine is running, I flip it back on it's wheels and it's good to go. But like da Rock says, it's much easier to side mount the engine or angle it 45 degrees down to the right. I like 45 degrees down to the right as it put the exhaust under the plane, less clean up after flying. Having said all that. Planes with a cowl do have a better appearance with the engine inverted.

opjose

Once you have the plane tuned PROPERLY in the upside down position, the siphoning rate when upright should drop to a point that it becomes far less problematic.

I had the same problem with mine as reported with the inverted engine, but once the engine was fully dialed in, it ceased being an issue... that is unless I forget and leave the throttle wide open with the engine off for long...

In the latter case fuel siphons far too quickly and starts dripping out again.

Normally on the UCD, the plane sits slightly nose high which helps to offset the tank-height difference when the plane is on the ground. By the time the LS needle is closed for good idle, fuel siphons at far LESS than a drop every 5-10 minutes, and you can eliminate that by shutting the throttle to cut-off and leaving it there, when not flying the plane.

jerrysu29

KrashTestKev. One Problem I have seen many times with Evo engines is that the Carb vibrates loose and the O-ring that seals the Carb from sucking air does just that. Sounds like this might be what is happening. As you stated only starts upside down, with the engine upside down excess fuel keeps the carb from sucking air, but when right side up the 100 sucks air in around the carb instead of drawing fuel from the needle valve assembly. We have found that the Evo remote needles are very prone to air leaks also. look at where the carb is seated in the block, know Loosen the carb mounting bolt setup push down on the carb, and while pushing down firmly on the carb and re tighten and see if it seats lower then at first To check the needle assembly run and watch for air bubbles in your fuel line if there are bubbles more than likely one or more of the fittings are leaking air through. We found the very same problem you are having in a GP Frenzy with an Evo 100 mounted inverted I checked out for a guy in my club. The main problem being the Carb not seated on the O-ring inside the engine block. I hope this might help. Good Luck.
jerrysu29 Call Sign Wild Man

Roo Man

My Feedback: (1)

I have a used UCD 60 that the engine has been installed with the cylinder up. The previous owner could not get it to run right inverted.

I would like to invert the engine but would prefer relocating the tane to proper level. Has anyone done this and is it a major task?

One other thing, the engine does not have any off set. I printed the manual off the mfg web site and it refers to offset only regarding the centering of the motor mount, it does not say how to add the ofset. I don't have a problem flying my SSE without offset, is it needed on the UCD?

bigdanusa

Put the landing gear on the top side of your plane and fly it inverted the whole time!

opjose

The plane was designed to run with the tank installed as it comes and with an inverted engine.

The documentation details an inverted mount.


Siphoning is only an issue if the engine is not properly tuned. Once tuned, the amount of fuel siphoning decreases to a relatively small amount with the throttle at idle, less than a drop every few minutes.

If you are having a problem, start the engine and leave the ignitor on.

Bring the engine to idle and let it sit with the ignitor for a minute or two.

Look for any gradual decrease in RPMs. If you see this lean the low end until the engine idles without an RPM drop.

THEN remove the ignitor and again look for an RPM drop. If there is a marked drop, the engine is still too rich.

You want a very small drop in RPM if any, when the ignitor is removed.

If you can get the engine to do this, then try a nose up/down test both at idle, mid-range and full throttle.

For added safety, do the same with the plane upside down.

Worry about all of this before resorting to moving the tank. You'll save yourself a lot of hassle.