bjcbs

My Feedback: (47)

I have a stock Golden Bee that I have used for over 100 flights on an old Ace motor glider. I have never maintained it other than changing the glow head once. It seems to start and run as well as it ever did. My question is, just how long are these little beasts good for? I have purchased a piston reset tool but have never used it figuring that if it's not broke... Is there some way of telling when the piston rod must be reset other than it's coming through the top of the piston? Is there any other preventative maintenance I should be performing?

-Barry

BMatthews

Pull out the piston and rod assembly and check for play in the ball socket. The tool is to reform the socket and eliminate that play. Done when required you'll get lots more hours out of your engine. Ignore it and the play will get worse and lead to reduced performance a broken rod due to the tapping that occurs.

DesignMan

In a clean environment, running 15% Nitro, 18% Castor fuel, Cox got one of their engines to run 400 hours without maintainence. It needed an electric starter to get going at the end, but it did run. Fox did a similar test on the stunt .35, and Duke gave up after running through a 55 gallon drum of fuel. Enough is enough!

The upshot is that we ruin our engines, they don't wear themselves out!

XJet

My Cox engines used to run fine for about 5-6 hours but then they'd get very fussy and run quite erratically.

The symptoms were that they'd just sag and lose power. Playing with the needle-valve, they'd go from a burbling four-stroke to a strained, two stroke but would not "peak" like they used to.

Despite trying new fuel, replacing the reed valve, needle-valve, blowing out the fuel pipe and needle for dirt, and removing any varnish from the piston/bore -- but they'd just slowly lose a whole heap of power. Plenty of compression left and no perceptable wear -- but no power.

It got so bad with my Black Widow that eventually it wouldn't even keep a plane in the air -- despite th efact that just a couple of months earlier it would haul it up at such a rate that it was almost out of site within half a tank.

Now that I've read more about these engines, I'm wondering if that might have been caused by a lose ball-socket in the piston?

Jim Thomerson

If you do not wish to spend the money on a reset tool, I have an 049 and an 09 piston, both with the rod sticking out the top. I will be glad to swap them for new, unrun pistons. This will save you wasting a lot of time running your engine until it self-destructs.

Jim

BMatthews

I guess we must have a clean environment up here or else I watch what I'm doing. Aside from one singular example I've NEVER worn OUT any of my Cox engines. But they are wearing. This is evidenced by the fact that when I build up an engine I actually look for the looser piston to cylinder fits. I find that as long as they are only scuffed from wear and not actually bent or scored that the relatively loose engines actually run faster.

The one notable exception I'm referring to is a Baby Bee I put on a little control line trainer and then me and a pack of Wolf Cubs (the ones with hats, not the furry ones ) took it to a park and proceeded to introduce the whole 15 or so of them to control line flying. The ground was super soft and muddy and the poor engine took plenty of opportunities to go gopher hunting the hard way. At one point I restarted the engine and it was running terrible. Barely turning over. And then I noticed that terrible black goo was coming out the exhaust port. I stopped it and looked it over. The air intake wedge in the backplate was jammed full of MUD and that fine talcum like mud was being slowly sucked into the engine where it was doing a great job acting like a grinding compound on the poor thing. Activity stopped for a few minutes while I took off the engine, partially dissassembled it and squirted the poor thing out and then we were off agian.

It never did run quite right after that.... Seems to have a singular lack of compression since then

Japanman

I had the same problems- but i found that it was cured by a new piston and liner set. I only had this problem with my T.D though, not the reedys.

A.J.C mentioned a trick of heating the cylinders to red hot and cooling slowley- they shrink slightly. then they could be re-lapped to fit the (worn) piston.

J.M

ajcoholic

My Feedback: (10)

Yup, heating and relapping/homing works on 9 of 10 cylinders. Mind you, it has to be a nicely worn out one, NOT full of gouges and such. You are removing such a small amount, maybe a few ten thousandths..

I have worn out so many cox engines from flying cl out on the mine tailings.... crash and get a bit of the rock dust in there and within seconds you have a nice, loose engine

AJC