Hey guys

can anyone let me know the factory carb settings for a Quadra 42 (fiitted to a Byron P51 with reduction drive) , my Q42 has gone off song and now refuses to run, it starts breifly when primed bu quits after a few seconds.
The engine was new and ran well for the first few flights but got increasingly difficult to start, the carby seems fine with all seals like new .

any suggestions?


cheers

Alan

The Quadra manual says 1 turn out on the high speed needle and 1-1/2 turns out on the low speed.

Good luck and let us know if there are further problems.

Bedford

Bedford

thanks for your help, .

I will give that a go


cheers


Alan

Has it been awhile since the engine ran? If so you may want to check the screen in the carb for plugging up and also check the valve "flaps" for sticking to the carb. Some oils are stickier than others and can cause this. If they are stuck just stick your fingernail under the edge and lift them free. Just something else to think about.
Cheers, Dave.

I'll bet that Mogman hit the nail on the head, you have a plugged screen. Take off the side of the carb that has the large single screw in the center. you will see a small cavity (about 1/4 inch in diameter) with a very fine mesh screen in it. Carefully remove it with a sharp pin or equivalent and hold it in a tweezers or needle nose and burn off the fuz you see collected on it. Rinse off the debrie in clean fuel or alcohol and repace it back in the cavity and put the plate back on the carb.

Thanks Guys


I will give that a go this weekend.......the engine was apparently brand new and it's only had around 4lt os fuel through it, but I'll give the carby a cleanout and see how it goes.

Again many thanks.......the Byron P51 is one sweet bird and it's frustrating not be able to fly it !


cheers

Alan

Alan, let us know what you find and how you make out.
Cheers, Dave.

Hey Dave


No Luck [&o]
I disassembled the carby and cleaned every thing, checked the mesh screen for "fluff" and made sure all gaskets and seals in good condition (Althought the model is 15 years old, the engine was replaced with a near new - hardly used Q42 when I bought the model).

After buying the model a few months back the engine started fine after priming a few times but got progressively harder to start until it deadsticked just on landing on the alst flight (5 weeks ago), since then no go.
I have tried resetting the H/L needles to the factory needle settings and replaced the spark plug and checked the magneto gap but still the same problem.......it fires on the prime (stick finger in carby to choke.....turn over the engine few times until carby is good and wet with fuel and swing the prop) but refuses to run. i have even gone from 30:1 mix to 50:1 thinking maybe the oil content was too much now that is was run in???

I am not sure of a Quadra service centre here in Australia so I may resort to a local chain saw dealer to look at the carby (Walbro's seem to be common to most chainsaws and weed wackers) hopefully they may have an idea.

Any other ideas would be much appreciated

regards


Alan

Alan, just out of curiosity are you hand flipping the prop. If I remember correctly the prop is a gear [belt] reduction drive. Have you tried using an electric starter? The magnet in the flywheel has to spin past the pick-up at a good rate of speed to generate a spark.This is why most Q42's have a spring starter on them. Also how are the fuel lines and the fuel tank? Just a couple of thoughts. As you say it will run on the prime, it still sounds like a fuel supply/carb problem. I have had problems in the past with the diaphragm that operates the needle, it becomes inflexible to the point that it won't push down on the needle operating arm, not allowing enough fuel in. Also check that the steel cover plate[ on the diaphragm side]has an unobstucted air hole. If I can think of anything else I will let you know.
Cheers, Dave.
P.S. Have you tried opening the needles some more? If you have to go more than 1-3/4 to 2 turns there is a blockage, or not enough fuel getting in.

Hi Dave


Yep...hand starting ...the plastic spinner on the Byron is not up too a big electric starter and it started just fine for the first few flights, as the prop has the reduction gear each flips is at least two revolutions of the magneto pickup.
As you say, it is definitely a fuel supply problem........I have replaced the tank and all fuel lines.....the fuel actually runs to the carb with gravity due to the tank being high in relation to the carby and pours through when the line is disconnected from the carby.
The diapragm seems fine, very supple and no holes and yes the air breather hole on the back plate is clear and I have progressivly wound the H and L needles out up to four turns with no result .

Obviously a blockage some where but I'm stumped if I can find it[:@], all seals look fine and it is as clean as a whistle.......

I think I'll resort to taking it to a "weed wacker" shop and get the experts to rekit the carby.........these engines are so simple, a spark some fuel and air and they go.....

Thanks again for your help Dave but my shoulder is killing me from all the prop flipping and the frustration has now got the better of me.......... so it's off to the shop.

Do you know if Q42's are still available in the States?

Hi Alan. Q42's are still around as are U.S.41's[virtually the same engine]
Cheers, Dave.

Can anyone tell me where I can download the manual for a Q42? I just bought a used Big Bingo with this motor, but the owner didn't have the instructions. if there is not a down-loadable manual, can anyone give me proper starting and operating instructions?