rcgood

I got my zdz 80 from RC Showcase back after a check-up with a clean bill of health. They opened the carb, cleaned it out, checked the whole engine, put a new spark plug (I assume they adjusted the gap) ran it and adjusted the needles. The first time I try to start it and it won't start. How weird because before that I never had a problem starting it. I literally new exactly on what flip it would start 99% of the time. The only thing that changed is that I got a brand new ignition but I doubt that's the problem???

I choke it, full throttle, flip and a few times and it pops. I unchoke it, put throttle to about idle and flip it a few more times. Sometimes it pops one or two more times then it's dead. Nothing more. Tank, tubing (whole setup) is new. It looks like it's getting enough gas (drips out of carb after choked and it pops, fuel line to carb is full), I imagine if ignition was bad it wouldn't pop 2-3 times. This weekend is my only chance to maiden my new ship and practice before an IMAC meet and this has kept me home today. . Any ideas? Where should I start troubleshooting?

Rcpilot

My Feedback: (78)

Crack the throttle open a couple more clicks and give it some air while your flipping. Most gassers like to be started at a high idle.

Dan767

My Feedback: (19)

If the carb is adjusted too lean, the carb will flood and it won't start. As long as you're sure the chokw is closing all the way, I'm betting that's what's happening. Open the low needle just a little and try again. If it floods again, TURN OFF the ignition, open the choke and full throttle. Flip the prop six or seven times to clear it. Close the throttle, turn on the ignition and try again. You may have to re-choke it again to get it to start. Good luck flying IMAC.

Prapan

I have exactly the same problem on ZDZ 50NG. With new engine it is hard to start. My issue is fuel does not come into carb completly although I flip more than 50 times and follow the procedure based on Mike of RCSHOWCASE.
I only start by removing the spark plug and using hi-torque starter to spin the spinner and until fuel flooding out the spark plug hole. Then I reinstall plug and flip by hand 2 - 3 times.

I cannot do that so long as it is unusual so I made a decision to solve the problem as follows :-

1) Remove the carb and check all parts / clean filter / check spring for diapharm pump with gas soline.
2) Use air pressure to clean holes inside carb.
3) Assemble them back.
4) Note that from 1) to 3) I didn't see anything wrong, every parts of carb are good.
5) Make sure we set up right position for sensor and full battery for inigtion (6 Volts)

Now what I made it difference is that I closed the hole of choke by small screw and nut and adjusting choke servo to make sure that choke will be closed completely.
I also remove the FILTER that was connected in between the FUEL TANK and CARB. DUBRO. I also see that filter is clean.

With above changed I made, I wish it will solve the problem since that only things I can do best.

Then I assemble carb back, and follow the procedure for start up as Mike from RCSHOW CASE recommend. here....

-------------------------------- procedure from Mike Dooley ------------------------------------------------------------------------------------------------------------------------

Set L needle to 2 turns, H to 1.5. Choke plate must be closing completely. Be sure hall sensor is mounted 6.5mm as indicated. Be sure battery is in good conditon.

Use this starting procedure as indicated in instructions:

Choke closed, full throttle, ignition OFF, 5 flips

Choke open, full throttle, ignition OFF, 5 more flips

Reduce throttle to mid/high trim, ignition ON, 1 flip, it should start.

Be aware of time out feature on ignition of approx 1 minute. Re-arm if needed by cycling on/off/on.

The ZDZ engines use a rotary valve and cannot be started same as DA or 3W engines.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Now my dream comes true. My ZDZ50NG was changed from "HARD TO START" TO "EASY TO START". After closed the choke and full throttle, then I saw that after I flip the prop for 5-6 times the gasoline was sucked quickly into carb (30 times before solving problem and cannot succeed). ZDZ engine once it starts, it run very well and a lot of power.

Seems to me ZDZ does not like FILTER in between fuel tank and carb. or Suction is not enough so I close the hole at carb.

Not sure that they are 100% solution but anyway my engine starts easily every time I fly EDGE 540.

Hope this helps.

rcgood

What do you mean "give it some air"?. Prapan...are you saying that the only thing you changed is your starting procedure and that's what made the engine start easily? It's funny because that's exactly the procedure I used last year when I used this engine and that's why I said that I knew exactly which flip it starts on. This is the first time I tried starting this engine the "DA way"....Hmmm...maybe that's what I'm doing wrong. And I didn't even think to change the needles assuming they were set perfect from RCS. I'll try these tomorow morning and hopefully it will work...Last chance to maiden the new plane and get some manuvers in....fingers crossed

Zeeb

My Feedback: (41)

My experience with my ZDZ's indicates they don't start as well using the DA method of choke till it starts, they wind up flooded.

First start of the day I usually go wide open throttle (as mentioned above they seem to pull fuel better that way), closed choke and about ten flips. Throttle closed to just above idle and flip it until I hear the "snotty nose" sound, usually about five more flips then ignition on, choke open and they go the next flip. Subsequent starts of the day if it's been sitting for an hour or so is throttle cracked, choke on for three flips, choke off, ignition on and they usually go the first flip. If it's still a little warm, one choked flip and it'll go the next flip. I occasionally misjudge that and get them flooded, but not very often.

You need to verify the needle settings to get it going the first time then adjust for your location/altitude. Nine times out of ten if a ZDZ won't start it's fuel related. RCS DOES NOT recommend inline fuel filters nor felt clunks. Then you're down to verifying that there are no air leaks in the fuel system before you get more into engine diagnostics, or at least that's IMHO...

edit info:
After looking at your posts on several other threads, it looks like I took a few things for granted...[X(]

You will have to verify engine timing, there is an excellent post or two with pictures on one of the threads you posted on, of a guy doing his ZDZ-50. Your 80 is the same. I'm not positive but IIRC 6.5mm is correct for your engine but you need to verify that. The choke plate has to close completely or it's not going to get the job done. Then verify throttle plate direction as noted below. Again, needles set per RCS recommendations and no air leaks in the fuel system.

I'd track down links but I'm on my way to the field, hope you get it going...

TLH101

My Feedback: (90)

Make sure the the throttle is working the correct direction. I have seen it several times, on engines that have removable throttle arms. The throttle plate retaining screw "head" should be towards the engine at low throttle. When you look in the carb at low throttle, you should see the screw threads, not the screw head.

rcgood

Well rub salt on the wound why won't you? . I know which thread you're talking about but they say put piston at TDC which I don't know what that is. I posted and asked but didn't get a response.

It seems that I solved the problem though. I feel dumb now. All I did is richen the low end very little. Duuuuhhhh...I knew that, but the fact that they were perfectly set by RCS was so embedded in my mind that I totally dismissed it (untill I read your guys' replys). It started right up. Now I have to put a stronger servo on the throttle. I tried to see if a HS-81MG will do (to save weight) but the arm goes back and forth (from the shaking I guess) pretty bad when the engine is on, changing the throttle settings.

Thx for the help.

Tired Old Man

My Feedback: (1)

A little more general engine info. There's no such thing as "factory settings" At best they are close engough to get the engine started, and no more. Every engine of every size and manufacturer has to be tuned to the specific location, fuel mix, and propeller size.

Top dead center (TDC) is best found with a dial indicator, but the poor man's way is to remove the spark plug and use a soft wood dowel to locate when the piston comes up to the top of the stroke. Rotate the prop a few times while making some small marks on the stick when the piston is high. The mark lowest on the stick after doing that a few times is TDC.

Big_Bird

My Feedback: (1)

I wanted to make a comment about your use of an HS-81 servo to save weight. I was using an HS-81 on the throttle and kill switch on my G-62 powered Giant Aeromaster. Neither servo lasted more than a few flights. They just couldn't take the vibration. Good luck on yours.

TLH101

My Feedback: (90)

Maybe try the HS-85, it's a bit beefier, but not a lot bigger, or maybe even with a set of metal gears.

Big_Bird

My Feedback: (1)

The problem that I experienced with the HS-81 was not the gears but the fact that the motor winding is so delicate that it will actually break at the commutator bars. The servo is great for electric planes where there is not much vibration.

Tired Old Man

My Feedback: (1)

Gassers and mini servos generally share a very short working relationship. The engine stays forever but the servos come and go relatively frequently. Eventually you give up and trade out the mini for an average sized servo and then get to forget about it. You could get lucky, ya never know.

JoeAirPort

My Feedback: (41)

My experience with my two new ZDZ 50 NG's is that they start easier with a richer low needle. I have them tuned almost identically but one has the low needle at 1 3/4 whereas the other is only 1 1/2. The one that's 1 3/4 starts easier. I like my low needle tuned so the engine has to be a little warm before it will transition. With ZDZ's this seems to make for harder starting. It starts eventually but it takes a few starts to get it warm before it will stay running. So there seems to be a trade off. My DA was the same way. On cold fall mornings, it was hard to start.Then in the afternoon after it warmed up it was fine.

Prapan

Hi rcgood.,

My changed was to close the hole at the carb choke by screw, and then remove the filter in between fuel tank and carb. Those are only the changes I made. I tried to start based on Mike and also another way around like 3W or DA. It is working well.
But it may take a bit more time (several flips) to get engine start compare to 3W or DA. I am not sure that the the procedure from RCSHOWCASE is the main solution. I think it took several factors.

Prapan

I have the same feeling and support information of JoeAirport. Take a bit more flips than 3W or DA. Some times I flips 10.

NM2K

My Feedback: (14)

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You should be talking to Mike Dooley or one of the gang first. Give the guys that fixed it a chance to help, not that we aren't interested. <G>


Ed Cregger

Zeeb

My Feedback: (41)

Glad you got it going...

Silversurfer has explained one way ZDZ talks about finding TDC, but the other quick way is shown/explained on RCS's website IIRC?

That is to line up the trigger (I can't remember exactly what they call that thing right now...) on the crankshaft with that rib on the engine case which is 90 degrees to the cylinder line. If you get it close you can feel it at TDC as you go each direction past that rib. Just line that trigger up with that rib. As for checking with the sparkplug pulled, you can do that if you'd feel better about it the first time, but one of the pictures shown on that thread I mentioned was of the 50 with marks on the crankshaft obtained by pulling the sparkplug, that's why I mentioned that thread in response to a question you posted about how to find TDC.

With my background I fretted about accurately finding the TDC, but Dick Hanson was kind enough to point me in the direction I use now and it's worked fine...

edit info:

Here's the thread with the pictures I was talking about. Take a look at the posts numbers #5 and #7 by JoeAirPort...[8D]

http://www.rcuniverse.com/forum/m_5533790/tm.htm

captinjohn

Hey all you guys that flip to your arm falls off....try a small shot of fuel from a prime bottle. If you got the engine on a fast idle ...it will start every time in 2-3 flips. The correct amout of prime and throttle setting is the answer...LEARN THAT AND SAVE YOUR ARM! Capt,n

JoeAirPort

My Feedback: (41)

I agree but with a lean low needle makes it trickier...and in cold weather....on many engines.

riplant

My Feedback: (5)

Did you find out anything about why your ZDZ80 pops a couple of times but will not catch? My 60 (which is almost the same engine) does exactly the same thing. RCS told me to take the carb apart and check for debris, clean, etc. Did that.. no help. Previous to sitting for about two weeks, my 60 was running perfectly and now it pops (sometimes a short burst-2-3 secs) then nothing. Thanks

rcgood

I think if you richen the low end it will start a lot easier. Right now my low is super lean and I have a hard time starting it. It has to start 3 times (runs about 2 seconds each time) before it stays running and I have to re-prime each time I start it even if it's 1 min after the flight. Once it's started and it warms up...boy does it run good. Really nice idle and all through the flight goes up and down instantly.

When I had the low end a tad rich it started much easier (prime and start first time). After a flight I could wait 30 min and not only it would start with no priming but it would be on the first flip every time. What I didn't like though was that it alaways took a while to settle to idle which is a big disadvantage on downlines and when trying to land. I personally would rather put up with the hard start than the latter.

Flyfast1

My Feedback: (1)

Is not using a fuel filter between the tank and carb recommended? I can see how using a fuel filter might restrict fuel flow somewhat, but is not using one worth the risk of getting debris in the carb? I have always used one and never gave much thought to it, just assumed it was always preferable, but perhaps not.

Movie man

My Feedback: (83)

I have a ZDZ 80 traded for it on RC Universe, no paper work, What size prop should I use?The Engine is already broken in.... Chuck Colwell

riplant

My Feedback: (5)

If the engine is in fairly good condition, use a 26x10 prop. I have a couple of ZDZ 80's. They are good and strong. Starting procedure when warm is a little different due to rotating valve (rv) configuration.