Harigo

What size tygon fuel line should I use for my engine? Dubro has 3/32", 1/8", 5/32"

DarZeelon

Haris,


You can use whatever size is recommended for 80 cc gas engines.

Gasoline flows much more slowly than methanol fuel, since the stoichiometric ratio for gasoline is twice as high.

I believe 3/32 should provide sufficient flow, but just to stay on the safe side, 1/8" should be enough.

Harigo

Thanks for the reply. Still having rough running engine. I think I need to fly without the cowl and fine tune the needles. Engine is fine on the ground but changing tones in the air. Not getting consistent tone. Thanks

DarZeelon

Haris,


This engine will not be broken-in, until it has burnt about 3 gallons of fuel.

Calculating from this engine's specific fuel consumption, it will take about 4 hours at full power to do it.
Much longer if you fly at part throttle settings.

When it is fully broken in, you will be able to adjust it to smooth performance.

Until the break-in is done, run it a little richer than full power, both on the high speed and on the low speed needles.
A little higher oil percentage is also good.



No engine runs very smoothly before it is fully broken-in.

Harigo

Thanks.... will impatiently wait.

Harigo

I have had another half gallon through the engine and I think the engine is running smoother now. It must be that the engine needs about 3 or 4 gallons to breakin.

I am switching off the engine by switching on the choke by a servo. I was told that this is not good for the engine. Is that true?

I am also finding a lot of black carbon soot on the spark plug. How do I clean it? Somebody told me it is due to my switching of the engine with the choke. Or is it due to the engine being run on the rich side?

I also find the engine harder to start after the first flight. Is it due to me wetting the spark plug too much when I switch of the engine by choking?

Haris

DarZeelon

Haris,


Who was the "expert" who taught you to shut your engine down with the choke?
You don't shut your car engine down this way, do you?

You either shut off the fuel, or the ignition.

Of-course it is a mistake and all those telling you not to are right.


It is quite possible this will is what make soot on the spark-plug.

Soot on the plug creates short circuits, which can make your engine run rough...

Harigo

The engine is too powerful for my Great Planes Patty Wagestaff so I switch off the engine by radio two feet off the runway. Now that I know I should not use the choke I will install a remote switch so I can still switch it off by radio. Thanks

I also read somewhere that if the needles were set right the spark plug color should be, I think, brown. Is it true that you use the spark plug color to see if the needles are set right?

Haris

DarZeelon

Haris,

This is true.

When your needles are set too rich, the plug becomes sooty as well.

Too lean and it becomes glazed. Brownish yellow is about right.