Starting backwards .049.

I have two Blackwidows .049.
I do not have starter springs on these engines. Once I get the right needle setting these two engines seem to run fine. However when starting, 90% of the time the engine starts backwards. I have flipped the prop both ways and it does not make a difference. Is there anything I can do other then the starter springs to get them to run in the right direction?

Thanks
Paul:(

Thanks
Paul

I don't like 1/2a's, but the backflip works on big engines. The deal is that you need to bounce it off compression, not flip through compression. This would take a delicate touch on an .049, but might do the trick. Or put on the spring starter. A good hot battery will help a ton. Steve

The Cox fix was to add a spring to the front of the crankcase for starting. Much better starting. I think the springs are still available.
Steve

Speaking from years of experience with a variety of Coxes, put the spring on it.

LAST EDITED ON Dec-20-03 AT 10:19 PM (CST)
 
If the engines have the cone on the front you can touch it briefly with the end of a chicken stick and sometimes it will reverse. Be sure that you are pulling the prop all the way through compression when flipping the prop, we sometimes fail to do this. Backflip works some times, just be sure to bring it to compression in the normal direction. If you worry about the prop cutting your finger wear a glove or something to cover your finger.

Best thing is to use an electric starter for 1/2a engines from Miller Rc, Sullivan, or Norvel. Be careful though made for smaller engines they can still break a crankshaft.

LAST EDITED ON Dec-20-03 AT 10:17 PM (CST)
 
Sorry duplicate posting

We had a group of people with a Cox PT-19 when I was in high school. One of them got dubbed "Baron von Reverse" because, whenever he took off, he'd bounce a prop tip on the ground and the engine would all of a sudden start running backwards.

As a kid I ran Cox motors almost constantly and so I have very fond memories of the little critters.
As to starting backwards it is almost a sure sign that the motor is too rich. Close the needle valve a quarter turn and really slap that prop.
Dont be a wimp when flipping a reed valve motor, get aggressive with it and it will run the right way more times then not.
Dennis

When restarting hot with the right needle setting, stop the engine and blow through the exhaust to get rid of the too rich cylinder. Better yet, get one of the springs.

If you simply flick it, it will usually start backwards, The trick is to park the engine on compression (TDC) and then HIT it. Start with your hand maybe 2 feet away from the prop and hit it with your index finger as if you were trying to knock the prop of the motor. Springs are too fiddly.

You got that right, Dave! Flipping any of the Cox engines (don't know about the Conquest) is an exercise in futility. Mine, of all sizes, have always needed a head prime to start. Piston up or piston down, depending on the individual engine. Turn the prop backwards to vertical. Hook up the 2-volt battery, hit the prop forward, and turn it loose. I use a spring if I have it but don't need one on an .049.

I've tried the 'hitting it' method before. I'm a little on the clumsy side and got tired of taking the motor off the front of the plane, with the front of the plane.
However, it usually works for people of more refined motor skills.

I also hate bending needle valves all the way over, and that little slice that the clicker makes in the end of your finger when flipping.

I am lacking in innate skill and agility (never learned to dribble a basketball, for example) but compensate to some extent with bull-headedness. These days I only occasionally take an engine off an airplane, and I've learned to wear a glove. Actually I now use a rather elegant flick of the wrist rather than a full arm swing.

LAST EDITED ON Dec-21-03 AT 01:37 PM (CST)
 
>I have two Blackwidows .049.
>I do not have starter springs on these engines. Once I get
>the right needle setting these two engines seem to run fine.
>However when starting, 90% of the time the engine starts
>backwards. I have flipped the prop both ways and it does not
>make a difference. Is there anything I can do other then the
>starter springs to get them to run in the right direction?
>
>Thanks
>Paul:(

Paul the engine needs to be broken in. JUST run them backwards is ok to break them in. IF that don't work ADD an extra copper gasket under the glow plug It will work. ALSO try a larger prop 7x4 to break it in.

scott(FLYWHEEL)Riese

Lots of good advice. I will have to wait for another day when the wind and cold are not in sight.
Thanks guys
Paul

Thanks
Paul

As former Director of Engineering for C*x, and a lifetime user of their engines, occasionally nicknamed "Mr. 1/2A" (I hope that refers to engine size...) I give you the benefit of my experience. Get an electric power or spring starter! Flipping reed engines by hand is a waste of time and effort. I don't even mess with hand flipping ANY engine under .15 size. Starters save fingers, time, effort, blood, flesh, sweat and tears. What's to lose? For the small engines, I like both the Miller and Norvel starters. I tried the Sullivan, exchanged it because it vibrated like crazy, then just flat returned the 2nd one as unusable. Pity!!

If all else fails buy a pusher prop....when it is running backwards.....your plane will go forwards HA!!!!

You'd expect that from someone in New Zealand......

Where up is still up, but is your guys down.

You should have seen my buddies CG swordsman or whatever that trainer was when I launced it with the engine running backwards. Sure did stop quick.

I stupidly hand-launched one of Ryan's plank wings with the Babe Bee in reverse. Lucky not to get a lap full. The flight was brief and bizarre!

I agree with Larry. Hit it with an electric starter. You'll spend more time in the air.
Chris

ROFL!!!

All these reasons why the things run backwards. Come on.. it doesn't matter if they're rich, lean, not broken in... Unless you use the starter spring, have a really powerful flipping finger, or use an electric starter, it's a simple fact of life that half the time, they'll start backwards. Why? Because they run equally well backwards and forwards, unlike rotary valved engines. AND those little props don't have enough inertia to guarantee they won't bounce off compression and start the other way.

More often than not, if it starts the wrong way more than twice, I just flip it the other way, and it'll start up the right way. Larry's right - use a spring starter. I use them on my Norvels, too, by the way. Beats flipping props.

Thanks guys,
I guess I need to find some springs. Anyone have a good source?
Merry Christmas
Paul

I got a bunch off e-bay a while back...

It might be possible to re-bend the Norvel item. The Norvel item might even work on a Tee Dee.

Rootbeard, I got some new ones. How many do you need?

$2.00 each.

Bigiron

Hey Scottie,
Never, I repeat never run your engine backwards! If it starts backwards immediately kill the motor. There are two problems when you run an engine like this backwards. 1) The crank is now forcing itself against the reed and is basically eating itself up; this is why you shouldn't use an electric starter on any reed type engine. 2) Running the engine backwards doesn't allow for any air to be flowed across the cooling fins, so you're basically overheating the engine severely.
As for the backwards starting problem, there is absolutely nothing you can do consistently to solve this other than by using a spring. We racers have tried everything. Sometimes rich engines or other compression problems will yield this backwards running tendency but if the engine is needled correctly then the problem can't be solved by flicking backwards or forwards.
And believe me, we racers who depend on good starts know what to do and no one is consistent without a spring.
And finally, Scott, you're my buddy but if I ever catch you with a 7x4 prop on an .049 I'm cutting you out of my will. A good break-in prop is around a 5x3, maybe even a 4.75x3. Let the engine unwind a bit and work up to a 4.75x4. -Todd

I dunno.. I've seen them used in pusher configurations before and the thrust plate should keep the crank pin out of the reed keeper (which, I imagine, would immediately cause the engine to stop, if it were hitting it). There might be added wear where the thrust plate rubs against the front of the crank, and there is a washer there, too. Wasn't the Cox Shrike (the tethered car with the roll bar) a pusher?

As long as you're not running the thing lean, I don't imagine the lack of prop blast over the cylinder would matter too much either.. a lot of the cooling comes from the fuel, and 1/2-As often run too cool anyway.

Larry's the .049 expert - if he says I'm way off base, so I am..

Actually, running backwards isn't all that big a deal. C*x did that on the Shrike car at least, and I think on one of the boats. It has been done on a variety of kit models.

The crankshaft has clearance to the reed valve housing in a new engine at least.

The original Killer Bee and Venom engines had a stainless steel washer between prop-washer and case to allow heavy handed use of an electric starter. Tee Dees used either fiber or stainless steel washers. Other C*x reed engines have used brass prop-washers to similar good effect.

I have a Cox I found in the garbage on a plastic CL plane with a backwards spring and prop installed. Someday I will figure out how to start it, but I need to figure out how to get the prime past the muffler.

Most C*x mufflers have a black metal spring around the outside that can be rotated to expose an open port. I don't recall one that just was totally sealed up. Post a picture, maybe? Take the muffler off completely? Drill a hole to squirt fuel through?