hello all !!! i have 3 questions/problems. please help!

1) flying Great Planes U-Can-Do 3D 90, put a saito FA80 on it. Flying slow as hell! This is my first 4 stroke engine and my biggest plane yet. Is this engine enough power for the plane? What size and range of prop should i use with this plane and this engine?

2) EVO 46 engine- sits at idle for about 30 seconds then slowly starts dropping and cuts off on its own without me touching the throttle. Many guys from the field have tuned it but i still have this problem. If i leave the glow stick on it, then it never dies even at idle. plug IS good, used plug tester and have replaced plug. i use medium plugs, if i use a hot plug will this fix my problem? seems that as long as the glow stick keeps the plug heated its fine. I dont really know being a beginner. what should i do?

3) according to prop sizes like 11x6 , 12x8, even a 13x4 ive used......a longer prop does what exactly? and the pitch does what exactly? i dont understand the performance difference of speed and torque and what it makes my plane do using certain different sizes. anyone have a simple explanation? how do i pick the best size?

anyone feel free to tag one or more of my questions, ANY help would be so greatly appreciated!!!!
thanks
-kevin

The FA80 is one of Saito's earlier engines. It does not have enough power for the UCD.

The Evo 46 sounds like the low end is rich. Try this: remove the glow driver and let the engine idle until the RPM start to drop, but before the engine dies, pinch the fuel line with a pair of long-nose pliers.

If the RPM slowly increase and the engine continues to run for several seconds, it is too rich on the low end. Remove the blue collar next to the carb and turn the low end screw clockwise about 1/8 turn. Start the engine and see how it idles. Each time you do this, bring the engine to wide open and readjust the high-end needle. Repeat until it idles properly.

Props: a longer prop with a smaller pitch will act like a lower gear in a car. You will get less speed, but more power.

awsome minn thank you so much! i have a super tigre .61, do u suppose that would be enough power for the UCD? if so, what size prop would you reccomend? and i will try that tip for the evo first thing in the morning! thanks again!
-kevin

The 61 would be a better choice. Not sure on the prop. Maybe 3-D guy could tell you better

http://www3.towerhobbies.com/cgi-bin...&I=LXBMZ6&P=ML

"REQUIRES: Engine: .61 -.91 (10-15cc) (2-stroke) OR .70 -.91 (11.5-15cc)(4-stroke)

NOTE: For maximum 3D aerobatic performance, choose an engine in the upper power range. The O.S. Max .91FX (OSMG0591) is an ideal engine to utilize the full aerobatic potential of this airplane. "

from the above website.

Wingman,
I think your talking about the UCD 60 size. My UCD, may it rest in peace had a O.S. 91 Surpass w/pump, it had a 15X6 APC on it. This plane is not going to be a speed demon, it just is'nt made to go fast. It likes to go slow and do nice 3D stuff, with that fat wing too much speed is not good. You don't mention what prop you used on the Saito so it's hard to tell, but Minn's probably right that it's just a bit underpowered from what I've heard about the older Saito's.
As Minn says, lower pitch gives more climb, higher pitch gives more speed.
I would put a 13-4 on the 61, or for more speed a 12-6 or 7.
The UCD is going to be happier with a 91 4 stroke or bigger.

hey stunt thank you! i had tried a 14x6 and a 12x6 on the saito fa80. i do understand that this plane isnt meant for speed, but the thing can barely climb a hill. if it wasnt for that huge wing it seems itd drop to the ground. cant even do a single loop without it fallin. i'd love to put a 91 on it...but the best i got is the ST61. hopefully that will do a lil better than the saito80. ill try those props you recommended on the 61 and see how it does! thank you much for your help!


*** on the EVO46 issue...got that sucker to idle beautifully now without dying or chokin up! thanks a ton minn!

*** i know i should know this by now but, now when i go from idle to wide open really fast it dies....if i go slow its ok tho. does this mean HS is too rich or too lean?...or more tuning needed on low end? =/ and weird thing is i seem to be turning the high speed valve 2-3 turns in both directions trying to peak but i cant hear a difference in the rpm! what the? does this mean its time for a new HS valve or needle or both? HELP!!!!!!

-is this hobby supposed to relax you or raise your blood pressure?!?! =)~
-KEVIN

Don't throw that FA80 away!

If you ever go fishing, it makes a dandy boat anchor

ahhhhhhh are you serious? i just bought that used...ima newbie...was told it was a great engine w lots of power. lesson learned. so what IS the FA80 acceptable to use on? a 46 size plane maybe?

When the U-Can-Do is flying within it's design limits, it appears to be flying as slow as hell... almost at a walk.

It's a 3D plane after all. You need to mate it with a 3D prop!

You want a larger diameter but low pitch "wide" prop with that engine.


Since that engine specs out the following

Saito-80 12x9, 13x6, 13x8

An APC 15x4W will be about perfect for the engine and plane combination. It puts the engine right in the middle of it's envelope.

The plane will seem to crawl across the sky, but it will have plenty of torque because of the larger diameter.

No need to change out the engine so quickly.

The low pitch will also permit the engine to rev up a bit more, but not too much.

Try one out and see how the plane handles the verticals.

If it seems to have no problems pulling itself straight up, then you may find that you could leave it this way... you could change out the engine if you do not like it... just remember that while it may climb uphill all day long, it just will not do this quickly!


It's a relatively cheap test... who knows you may leave the engine in after trying this.



Re: Dies

Richen the low end about 1/4 turn and the high end a click or two, to cure the dying out when throttling up.



I fly my Giant U-Can-Do with a Magnum 180 RFS and I'm using an 18x6W prop for comparison. This plane is much bigger and heavier.

The plane flies sooooo slooooowly, that it is easy to control through 3D manouvers.

My old Funtana s90 uses a Saito 1.00 with a 16x4W prop and power is NOT an issue at all... I could hand lanch it if I were so inclined ( and stupid ).

Minnflyer has it wrong.
That FA80 is a fine engine. Try setting the valve lash and see if you don't get some more power out of it.
That is a fine engine for a lighter sport 60 size plane or any of the few 50 size.

Wingman,
There you go, put that Saito on a 46 size UCD. Missleman might have a point there, check the valves, maybe the old Saito is ready for a rebuild.

I think I remember reading they were a heavy old pig. The ST 61 should be much better than the 80.

If I had the cash I would go with a YS 110 on the UCD. My UCD would hover at about 5/8th throttle with the 91.

That FA80 is a fine engine. Try setting the valve lash and see if you don't get some more power out of it.
That is a fine engine for a lighter sport 60 size plane or any of the few 50 size.

........whats the valve lash?

Download the manual for a Magnum 91 four stroke from the Hobby People site
http://media.hobbypeople.net/manual/210970.pdf
Read page 8 a few times. The "valve clearance" is the same thing as "valve lash" and your Saito needs the same clearance as the Magnum.