Hi All,

Sorry for thsi post, but I'm stuck !

I've got a trainer with a MDS MDS40 Pro Aero engine in it.

I can see where the server rod is connected, but it will not open the air hole, it look like its stuck. Its a new engine. What I need help in explaining what each screw does to the engine (A B C & D on the photo). If got my first lesson on the weekend, so it will help me learn if I know what they are talking about.

A is where the servo rod is attached to the link. The "hole" (sorry, don't know what its called) between B & C will not open like it should ?

Is one of the screws locking the engine?

Thank for your help,

Pierre

THE BEST ADVICE I CAN GIVE YOU AT THIS TIME IS STOP AND FIND A LOCAL CLUB AND GET SOMEONE THERE TO HELP YOU OUT,NOT TO BE RUDE BUT IF YOU DON'T KNOW WHAT THE HIGH SIDE NEEDLE IS FOR AND THE STOP IDLE SCREW IS THEN YOU WILL ONLY TEAR UP YOUR PLANE,GET AN INSTRUCTOR FROM YOUR LOCAL CLUB TO TEACH YOU AND YOU WILL ENJOY IT ALOT MORE.GOOD LUCK AND I HOPE IT ALL WORKS OUT FOR YOU.AGAIN I HOPE YOU DON'T THINK I AM BEING RUDE, JUST BLUNT

No problem, and that is what I'm planning on doing this Sunday. Just trying to learn what I can before then..

great .a is the throttle arm.b i really can't tell but might be an air bleed screw for adjusting idle mixture.c is the idle stop screw for the carb barral,just back it out till the carb closes completely and lock it down.d is the topend high speed mixture needle valve.hope this helps ya

Thats great.

Thanks for your help,

P,

First I'll say that maybee the engine might have been sitting around for some time without any after run oil and the old fuel/oil is gummed up the Barrel and it wont rotate due to being gummed up? (That looks gummed up to me from the photo)
A-Throttle barrel control horn
B-???Maybe a carb mount screw, cant tell from the pic?
C-Barrel stop (Idle adjuster)
D-High needle adjustment.

Altho the engine is new it can be gummed up and needs cleaning to free up the froze parts.

Hope this helps...I also reccomend hands on help with this...Don't try to fix it over the Forum as it will leave lots of room for error and you dont want that.
Shayne

I don't know exactly either. But don't let other people (aaahhhhemmm 3dd aaahhhemmm) discourage you from fixin it yourself. Piddle around on rc universe and ask questions maby you can figure it out yourself. Your definently at the right place! Thats not saying an instructor won't help you. Good luck!!!

Electrolight


Happy future flights

b looks like the pinch bolt that secures the carburator to the engine.the low end screw is just inside of a.

Your idle stop screw C looks like it`s screw is in pretty far, Try backing it out a few turns.

Another suggestions is to see if you can close the carburetor manually.
Disconnect the servo rod from the "hole" (or from the servo) and move the arm manually to see if it can close that way. This will let you know if the problem is in the carb or perhaps a linkage/binding issue.

B is the throttle barrel retaining screw. The barrel is the part of the carb that turns. There is a slot machined in the base of the barrel that causes the barrel to move side to side as the barrel rotates. It is this side to side motion that opens and closes the spray bar.

I agree that the carb looks gummed up. My advice would be remove the carb from the engine completely and then completely disassemble it. A soak in fresh fuel would probably help to loosen the gum. Take your time, work slowly, and take notes if necessary. Most carbs can be easily disassemble in a few minutes without adjusting any of the settings (low or high speed needles). This will also give you the opportunity to thoroughly inspect all the passages for blockages.

To remove the carb, there should be a screw on the engine that backs out at the base of the carb. Then loosen screw b until the barrel slides out of the carb (from the throttle arm side). The high speed needle assembly (opposite the throttle arm) should unscrew from the throttle body by turning the nut at the base of the high speed needle assembly.

When you put it back together after a good cleaning, things should turn freely without binding.

Brad

You should change that throttle arm connection. You are just asking for metal-to-metal interference with that connection.

Good Point, I am surprised it wasn't already mentioned.
A plastic clevis is a good idea at the throttle arm.

Thanks for all your help people.

A FRIEND AT THE FIELD HAD THE SAME PROBLEM, WE FOUND THE PUSHROD INSIDE THE PLASTIC TUBE HAD RUST ON IT, BINDING THE PUSHROD. DISCONNECT THE ROD FROM THE THROTTLE ARM TO ISOLATE THE BINDING TO EITHER THE ROD OR THE ENGINE. YOUR PUSHROD DOES LOOK A LITTLE GRUNGY.

This is a little on line etiquette thing I learned on RCU.....Don't use caps it is like yelling. Thanks for being so helpful with the new guys

I used heavy doses of WD-40 in my engine to clean it and didn't have to disassemble. It was pretty gooey like yours looks. I don't think the WD-40 has much of lubricating properies for your engine so I wouldn't turn the crank any more than necessary. Dump the WD when the junk dissolves and reapply if needed. I'd chase it with lots of fuel and turn the crank. Dump the fuel out and chase it with your choice of afterrun oil, tranny fluid or whatever you prefer to keep it from corrosion.

I was halfway thru typing at my usual snail's pace when I noticed the caps lock on. Too lazy to go back and start over. Sorry if it upset you.

BTW - that "hole" as you called it would prefer to be called a "throttle bore" or "venturi". Some just call it the "carburetor inlet" also.