I have a ucando 3d 60 size powered by an OS91FX and cannot get it to run properly. I have seen the suggestions previously but am posting this as a new post in an effort to get more suggestions.

In order to start the engine I have to turn it over on its back and once I have it running I can turn it right side up. Even then it still runs terrible and I can't seem to tune it so it will run properly. The engine ran gread on a 4* 60 and on the bench.

Please give me some suggestions on how to get it to run properly without buying pumps, regulators, etc. I also am trying to avoid rotating the the engine to horizontal.

Would greatly appreciate any help anyone can give me.

Thanks in advance,

doubledee

DOUBLEDEE
WELL YOU ELIMINATED MY SOLUTIONS IE: ON BOARD GLOW SYSTEM OR ROTATE ENGINE TO HORIZ PJAMESRC

Most two strokes that I have had in the past just don't run very good inverted without a onboard glow. That is why I only use four stroke engines if I am going to ionstall them inverted.

FYI I had a Thunder Tiger 40L with Thunder tiger Pro 46 in it! It would not idle! Always came in Dead stick! I put a Fox Idle bar glow plug in it! Never had a dead stick again!! Worked for me!

something is not right on the plane or engine had same combo and more people had it it may be out of tune or you have a fuel problem or maybe trying to idle to slow even pull the baffle out da mufler it may give to much presher change plugs i did not have 1 dead stick with mine never ran it on the ground started and took off

I had this setup to start with...advice from the feild experts...
"glow engines produce alot of oil and residue that at low idle will pool up and keep the glow plug from heating up....never put a two-stroke up-side down." (or something like that).
So I went on home and placed the engine on its side. Ran like a champ from then on.
To do this I had to take a dremmel and do alot of cutting to the side of the fuse to get the muffler to attach. There is a alot of material there, and it is double up....I was concerned...but pressed on. In addition I soaked the snot out of the balsa with thin CA and then put a coat of clear fingernail polish over it to fuel-proof it. After that I cut the heck out of the cowl to clear the muffler and went to the airfeild.
Flies like a champ with close to 100 flights (probably) and is one of my most dependable/fun aircraft I take to the feild. Good luck
....or...could be that your 91FX is a lemon...I had one and sent it back after several deadsticks and other concerns and they sent me a new one...The new one ran great after it had ran two tanks of 30% heli through it to finally get it to run straight. After that I switched back to 15% Byron and it goes smooth...no issues.
Hope this helps
Brett

I agree with LUDS96 above as to the fox idle bar or any hotter plug. Check the tank location and use 15% fuel. Also make sure the idle mixture is good or even maybe slightly lean.
What you are describing means you are not getting it started even with glow attached...Strange, although I have seen this on others.
Good Luck,
Twinman

I got a OS108 and it runs the same,no power can't tune it in right.. I figured the 108 would hold it in a hover easy. It would be ok for a few seconds,then go to full power and theres nothing there. Between half and full nothing different.. Nice tailslides though
Later Frank
vp njjf
www.njjf.org

Same plane, ST 90, same problem. The fuel tank on the ucd is about 3/4 to 1" above the C/L of the engines needle valve. Solution? Iron Bay fuel Regulator. My ST will sit at idle indefinately, and spool up with no hesitations.Best $50 I have ever spent!!!!!!

The way I got my 91FX to run right inverted in a razzle is to use a OS F plug. The little tip on the plug helps keep it from being covered or flooded out. I had no success with idle bars or hot plugs. They still blew out. Also I make first start of the day with an electric starter and the engine dry. No primeing or chokeing. Let the engine pump the fuel in while starting. After that it always startes on 1 or 2 flips with a chicken stick. The only problem I have with the OS Fs is after about 20 flights the shine comes off the eliment and they start quiting and I have to put in anew one (expensive). I had the same problem you are having untill I switched to the F.

Denis

I have an inverted 0S91. This like all my inverted engines needs to be started unprimed and the glow plug kept very clean during layup.

GLOW
Use a warm-hot glow.

TANK
Position so fuel is gravity fed to carb in airframe's starting position.

LOW NEEDLE
Low end mixture is on the leanish side.
Close Throttle to idle.
Fuel should drip slowly from the carb opening.

START
Do not prime.
Turn engine by hand two turns to check all is well.
Open throttle 20%.
Energise glow.
Turn engine rapidly with starter.
Engine sucks in fuel drops and fires in a couple of seconds.
If not check glow or for flooding.

AFTER USE
Probably the most important procedure.
Always burn off fuel in engine: empty tank, energise glow, apply starter for a couple of seconds.
Take care engine may run on.
Glow off.
Quick squirt of afterrun oil deep into carb, I use WD40, never ever had any problems.

STILL PROBLEMATIC
Check plug before starting, this can gather engine combustion byproducts and oil.
If needed, remove plug after each flying session, burn it clean ans store it for next time.

OBSERVATIONS
When cold the OS91 can be very tight.
You will need a powerfull starter.
I have never had a flame out following this procedure on an engine that is setup correctly.
Watch the richness of your needles keep them reasonably lean.
Good luck

I have a Moki 2.10 mounted inverted on a DP Edge 540. The engine is a bear to start by hand inverted but I just couldn't bear to cut a big hole in the side of the cowl. The engine is a power house once you get the fire lit though. I use an OS type F plug and on board glow that is set to come on at about 1/4 throttle. I also use a starter to start the engine, it can be started by hand but I decided I like flying better than flipping.

I have two 91fx and never had a problem-I have one inverted on dragonlady-the tank sits even with thrust line-never had a running or starting problem-no extra glow just stock as it is out of the box and I think I am running cheap glow plugs from tower-you know the one's eight for 10 bucks or something like that-it has been a great engine and I am running a tatone-universal muffler-the other side mounted with no problems and running stock muffler without the baffle and two foot spacer in the muffler-don't know if this helps but this what works for me =have a great day

I have a P-40 Warhawk with an OS LA 46 in it and it is inverted,i had a devil of a time to get it to run passed a half tank of fuel but i found that it was over heating and cut a hole on the bottom of the cowl and had no more problems.
As far as starting it never had a problem there,also my fuel tank is even with the carb and on cold days run it rich.
I just got done with another Warhawk but this time it will have an OS 70 FS in it and retracts it should be a screamer!
Good Luck!

Hi
I've had no problems with an inverted motor as long as your not priming the carb when your fueling and have always run the bottom end really lean and don't be afraid to run your glow in the red just to burn off excess residue in between flights and at worst you sometimes have to pull your plug to clean, don't get frustrated just learn a few tricks, check the o-ring on your needle because they do get to the point where they do suck air

My buddy has one of these with a Super Tiger in it. It would load up something fierce all the time, and fuel would run out of the carb just sitting there on the ground. The fuel tank is WAY TO HIGH on this plane. Hate to tell you this, but he had to put a Perry pump on his to solve the problem. Runs great now.