Reed Valve Troubles

I am looking for advice from all of you C*x reed valve experts out there.

I have in my collection about a dozen Babe Bees and Black Widows (all pre-Estes) Most of them run very well but a few of them, including a couple of NIB Babe Bees and a little used BW, will not keep running long enough to empty the tank. They generally start easily but die after a few laps.

All have been carefully broken in per C*x instruction sheets and I use MA 6x3 props. I have tried different needle settings, new glow plugs, piston reset, disassembly and cleaning, checking for air leaks around the tank/cranckcase seal, etc. All to little or no avail. Using Sig 15% and more recently Powermaster 15% fuels with 20% castor/synthetic. Using higher nitro (35%) helps but doesn't cure the problems.

Any ideas what is causing this? Is it just the luck-of-the draw with respect to tolerances, fit, or production batch? Someone once told me the front of the crankcase should be filled with automotive grease, anybody hear of this? What fuel are you guys using?

Or am I just expecting too much performance-wise? (And yes I have tried a Norvel BigMig 049 and it consistently runs very well - power about the same as a good Black Widow)

Thanks.

LAST EDITED ON Jul-20-04 AT 11:14 AM (CDT)
 
Is your pick up tube in the tank turned towards the outside of the circle?
John Tate
Norfolk Aeromodelers

SNIP>>>Any ideas what is causing this? Is it just the luck-of-the draw with respect to tolerances, fit, or production batch? Someone once told me the front of the crankcase should be filled with automotive grease, anybody hear of this? What fuel are you guys using?

No luck. Grease??? NO WAY.

First make sure that your Back plates are tight. NOW what position do you have the engine? Up Right? 90 degrees off? I'm taking about the Cylinder. The pick up tube must be in the lower right of the back plate AS YOU look from the back of the engine. Other posts will come. I'VE NEVER had a COX not run. Some do run better than others. Some run BUT make good fishing weights...LOL

OH MAKE SURE the LITTLE BLACK gasket in the tank is good.

Try some different props, too. The 6-3 MA is my least favorite prop. The Cox gray or APCs are better. Babe Bees really like the old Top Flite nylon 6-3 if you can find some. Sometimes a little smaller prop is better, too. The suggestions about the pickup tube and intake gasket are good, too. Little tiny O-rings from the plumbing supply can be made to work as intake tube gaskets. Aboout 8 cents each. We use SIG 25% nitro, straight 20% castor fuel with good success.

Most of my trouble can be traced to the reed/retainer, or the black O-ring. It is hard to tell when it goes bad.

"SAVE ALL THE PIECES"-Phil Brown

Most of mine were VASTLY improved by resetting the piston/piston rod ball socket. $10 little tool does the job, although I've done it with a tiny punch and a tack hammer.

Tools

>Most of mine were VASTLY improved by resetting the
>piston/piston rod ball socket. $10 little tool does the
>job, although I've done it with a tiny punch and a tack
>hammer.
>
>Tools

I had four BW's that I had quit using completely because of erratic runs or no runs, mucho frustration. Thought they were just worn out. At a suggestion from this board, I checked the piston/rod fit...all were loose, some practically falling out (one had in fact driven through the top of the piston). Borrowed a resetting tool and tightened them all up...Now I have three (exception: the one with the "holey" piston) very consistent running, easy-starting, BW's. Two I have even modified to run on pressure...works pretty well. I'm convinced. Check for a loose rod.
--Ray

Varnish is another cause of overheating and erratic runs. Clean the cylinder bore with 0000 steel wool or Davis diesel's bore brush.

Plugs go bad too. Glow OK, seal OK, but the element looks white instead of silver, and you get crummy runs.

I've heard a gun bore cleaning brush works OK, too, though I've never tried it myself. Might be a bit easier to find, locally. Not sure which caliber brush to buy.

LAST EDITED ON Jul-21-04 AT 07:27 AM (CDT)
 
I was having this same problem with my .049 engine. It took me several months to discover it was the oil content that was the problem. The engine would start and fun fine but after a few laps around the engine would die. Sometimes the engine would sound like it was about to die and the airplane would slow down for 1 or 2 laps then speed up and run fine again for 1 or 2 laps over and over. What was happening was the engine was getting HOT and the piston was expanding and getting tight in the cylinder and stalling the engine out. When the engine slowed down a little it cooled a little too and the piston would cool and contract then the engine would run fine again for a few laps until it got hot again. My fuel was 15% nitro 15% oil. I added 5% oil and it helped. I added more oil for a total of 25% and it almost fixed the problem. I have a 35 year old empty can of Cox fuel and it says 29% caster oil so I increased my oil to 29% and the engine runs fine now. Make sure your engine is running a tiny bit rich before take off it will lean out in flight.

Guys,

Thanks for all the tips. Lots of things to think about and try (and when it comes down to it that's half the fun).