problems with my DA50????
 

hi, i've got a few problems with my DA50. just a quick history about the engine....
when i got the engine, i also bought a bisson muffler and a bolly 22x8 prop for running in. the only mineral oil that i could find was castrol 2T and was running it at 32:1.
after running the engine and setting the needle, the max rpm that i was getting was 6300. someone suggested i cut the tip off the muffler and after cutting it i got 6600 rpm.
while doing all of this...... out of my first 6 flights i had 3 dead sticks and almost lost my plane.
then i changed my oil to pennzoil, changed my ignition battery and re-setting the needle and then the engine became a bit reliable. then i changed my prop to a menz 22x8 and i got my rpm to 7K
after about 15 flights i changed my oil to Motul 800 at 50:1 and the engine was running well.

now i have about 20 flights and the last time i went to fly and everytime i turned inverted or was in a up or down line,
the engine wanted to quit. the only thing i had changed was my vent line which was hanging about 2 to 3 inches from the bottom of the plane. someone said that that could possibly be the reason.
anyway, i fixed that and tried to run the engine on the ground, it ran unreliably and i was only getting 6600 rpm again. thought there might be dirt in my carb so, i opened it and found some dirt and cleaned it.
also, the carb bolts ware loose and i tightened them. now i'm still getting not more than 6600 rpms. why did my rpms dropped from 7k to 6.6K? and what makes that happen?
i live at sea level and it's very hot and dry weather. i have really played with both the needles and turned them from 2 turns to 1 turn to see what happens. but i cant get more then 6.6K.
i using a 6v nimh battery which fully charged shows 6.7v to 7v so, i don't think it my battery.
anyway, any input on what's happening will be helpful.

sorry for the long history.....thanks

RE: problems with my DA50????
 

Check this out,, it seems like you are having the same problem I did, mine would try to cut off in a knife edge,, loop, etc,etc, ,it ended up being the ignition switch, flying level was ok and when I would do a sudden move or roll it would cut off, it was the ignition switch wires moving around anyway here is a link to my thread,, should be helpful,,,
http://www.rcuniverse.com/forum/m_43...tm.htm#4380868

RE: problems with my DA50????
 

Check your pulse line from the base of the carb block to the carb. Make sure it is sealing on the nipple at the base of the carb block. I had one split right at the nipple and it caused the same problem you describe. If it is spilt or not sealing good you will probably notice some fuel on the back of the engine and on the firewall were it spit it out of the line.

RE: problems with my DA50????
 

thanks guys for the suggestions........ "jongurley" I'm going to go through your post but had a few thoughts regarding your suggestion. i checked the red and black ignition wires with a continuity meter and everything seemed ok.
i wanted to try to solder a tube to the diaphragm and put it in the box... to do that, do i need to remove the rubber diaphragm from the metal plate? if i leave the rubber and solder the tube to the metal, will the rubber not get damaged?
also, does the balsa box have to be completely closed? i fly with out a cowl so, i don't know if the diaphragm mod will work.

blkbird68...... i checked the tube and it seems to be ok, though i remember there used to be very little fuel around that area and could that be there because of a bad fit?
i will go and tie a wire around both the tube ends.

anyway, could the weather have something to do with the rpms? when i said it was " hot and dry " that was a few months ago and now we have the monsoons and it's very humid, could that have something to do with the rpm loss?

RE: problems with my DA50????
 

A quick way to check to see if you need to run a line from your static port into the fuse or a box is to simply put a piece of duct tape lightly over the static port on the diaphragm cover. If it makes the problem better, then you need to do it. If it doesn't make a difference then odds are that isn't what is causing your problem.

RE: problems with my DA50????
 

take the rubber diaphragm off before soldering.

The box needs to breath. I would drill some really small holes in it to make sure the box pressure can netralize. Some balsa is pourus enough as is. The point is to stop the direct air flow on the vent hole.

Yeah, the humidity will do this. It displaces the the oxygen making the fuel mix rich. Not sure I'd lean it out more though. Humidity robs power just like the heat does.

RE: problems with my DA50????
 

Hello ,
As you know I am the DA dealer in india. Though you have not bought the engine from me you send the engine to me and I will take care of your engine problems.

Sharad

RE: problems with my DA50????
 

Hmm..well I didnt drill any holes and it works great but maybe like Joe said, the balsa might be breathing..I put some rtv sealant around the tube and it works perfectly..so far[8D][X(]

RE: problems with my DA50????
 

HOW OLD IS YOUR FUEL AND IN WHAT TYPE OFF CONTAINER

RE: problems with my DA50????
 

when the engine was running unreliably i changed my fuel but that didn't help. i use an old methanol plastic can as my gas container.
i just made the carb mod and gone through the hole engine and the fuel system . i hope whatever was the problem is now fixed.
anyway, i'm flying tomorrow and will report on what happens.

thanks

RE: problems with my DA50????
 

HAVE U ran with canopy off so u can see the tank and fuel line
i am thinking your clunk has come off or has a crack in tube and when inverted air is getting sucked in
do this run the engine on half tank and watch for air bubbles in fuel line you will see pretty quick .
do u have a dubro filler by any chance as they can open slightly and air can get sucked in .

RE: problems with my DA50????
 

went flying this evening and no difference. the engine wants to quit on down line. i tried a knife edge and the engine was fine but after a few seconds in a down line and the throttle at idle the engine just starts to sound real funny and i have to level out for the engine to stay going. other then fuel pluming/installation, would a wrong needle setting cause this? also i've noticed when i touch the tip of the muffler i get this black oil on my fingers, is that normal?

thanks

RE: problems with my DA50????
 

It might be the needles,, just play with them,, make sure you lean the low end out far enough so when you throw the throttle to it from a idle it will hesitate, then richen slightly until it can set for 20 seconds and take the throttle,,, and I am like Josey Wales when I made the original box I glued it together with no holes or cracks and sealed the hose going into it with silicone, everything works great,,