I have about 40 minutes on my new ZDZ 40, 92 Octane, Stihl petroleum oil at 40:1, Zinger Pro 20 x 10. Prop is perfectly balanced (all directions), no spinner. Prop tracking is bang on. Hall Sensor set at 7mm from TDC (Falkon ignition v 1.3). Low end mixture set to leanest idle with no gasping on transition, high end set to peak rpm minus 200. Mounted on 73" H9 Cap232.

Starts and runs fine (after I figured out that they shipped it with the carb spacer upside down!). Peak rpm 6900 (10 degrees celcius, 4300' elevation, less than 50% relative humidity).

Vibrating the crap out of my airplane!! Idle is rough, as expected with a brand new engine, but midrange makes the rudder flail with harmonic vibration, and the elevators are a flapping blur at full throttle. The only thing I can figure is that I drilled the prop so that I can't align the blades with the piston. That is, there are no bolt holes aligned axially. I have the prop set so that the blade is 30 degrees behind the piston at TDC - i.e. just coming up to compression at about 2 o'clock.

Number one - could this be the reason for the vibration, with an otherwise balanced prop? Do most people drill so that two of the six holes in line with the prop blades ?

Number two - can I safely drill a second set of holes between the existing ones on a wooden prop of this size?

Will this vibration settle out with some more engine time? My poor little Cap will be a pile of sticks within a few hours if I try to fly it this way. Help!

KD

Where a balanced prop is mounted has no bearing on engine balance. Is the engine hard mounted,? I'f so you may have to rubber mount it. Some aerobatic planes are very lightly built and have bad vibration problems.

It's also critical that the engine box is rigid. Does your box have 4 solid sides? I'm not familiar with the Zinger props. Does it come with a 10mm hole or did you have to drill or ream it to 10mm? Perhaps you drilled it off-center?

Try running the engine with the wings on the plane. You will be surprised how much this will help.
Once I had a F* 40 with a Saito 50 on it. The wheels would jump off the ground without the wings on it

Thanks for your replies. The props were all hand-reamed and perfectly balanced (checked on two other balancers). Mounting the wing makes no difference. The little H9 Cap doesn't have an engine box per se. I tried a prop aligned perfectly with the piston, - no difference. The engine was hard mounted.

I'm going to take the engine off and run it for a couple of hours on a stand to see if it smooths out. If it doesn't I'll send it back. I thought these were renowned for their smoothness!!

KD

Last month put it back on the test stand attached to my WorkMate, ran it for another hour, with no improvment. Tried adjusting the ignition everywhichway - no joy. Emailed Topmodel France, who contacted the factory and (within 24 hours!) said that ZDZ wanted the engine back for inspection.

:thumbup: Kudos to Topmodel France for their quick response - I've heard they can take a while to respond, but not in my case.

Will update when I hear back from ZDZ.

KD

Please lets us know what happens. I have a new ZDZ80 and it vibrates like mad! I've tried three different props with the same results. I have it mounted to a stand I built and then c-clamped to a picnic table. Yes it is very sturdy but will knock over a twelve oz bottle of bud lite on the table. Sure runs strong though but no way is it going in my plane.
I have read allot here about how these engines are smooth operators but I don't see it. My father had the 40 in his DP extra and it would blur the tail unless the wings were on. Still, my os 160fx is smoother than these two.
And don't anyone tell me to lean the low end to smooth it out, if it gets any leaner it wont transition.

Dan

Hi DCH:

We would love to have that engine back for us to take a look at. This vibration does not sound normal, but vibration is heavily dependent on the airframe and or mounting environment and therefore somewhat, in this sense, subjective. We have many , many of the 80's in users models and vibration is not a common problem. We will do what is required to make you happy with the engine, and if required we will refund your purchase price.

Please contact Mike Dooley at 301-374-2197 to discuss the next step

David Garrison
RC Showcase
ZDZ and RCS Gas Engines
www.rcshowcase.com

I have a ZDZ 80 which runs smooth as silk and I love it. That's why I was so surprised with the vibration of the 40. Time will tell, I hope.

KD

I was going to post a thread asking about vibration with a ZDZ 60 but you seem to be having a similar problem. I mounted it on a Hanger 9 Extra and started it today. The vibration at low thru med settings was exactly as posted in this thread. High throttle smooths out considerably but there is still too much vibration for my liking. The prop is balanced and the engine is hard mounted. What should I first do? Is this normal for a new gas engine? I thought about changing timing or the low needle setting. This has caught me off guard and made me reconsider switching from glow.

By the way, I spent quite a bit of time trying to get the engine started using "factory settings" to no avail. Turns out the idle speed needle was only one turn out and the high speed needle was maybe 1/2 of a turn out. After resetting these per the manual it started. They are both currently at 1 1/2 turns out.

Thanks,
Chuck

Locally , there are a number of these engines.
The worst offender -which adds to vibration -is the prop-
The worst prop type for vibration -is a low pitch Zinger.
Also - some Zingers -especially notable, are the std types -not the Pro , which often have a flat grain pattern-- sometimes on one blade which allows a lot of flex-
This causes vibes and low performance.
The best props for low vibes -are the beechwood props -and glass props -
So Bambula/ Menz- Mejzlic etc are very good.
Also the thicker 12 " pitch props -cut down from larger props run smoother - as they are stiffer.
As for any of these engines being inherant vibrators - I simply have not seen that. So far -we always found a reason for vibration -and it was typically a prop- not always but now the first change out a vibration problem.

The instructions for the Zenoah G62 mention a specific position relative to piston stroke for the prop.

Vince

I have a ZDZ 80 in my tow plane and a hinge in the rudder lasts one tow. I am talking about a piano wire hinge through 1/8 thick printed circuit board hinge. It is hard monted and the plane shakes like hell! I am concerned I have an out of balance ZDZ and am concidering going back to the Zenoah 80 twin which I used for years with out this trouble and was hard mounted too!

lewdfinger did you get the motor sorted out and if so what was the problem?

Crash

I have had problems with an RCS 140 in the last week and vibration was just one of them. I think I got a bad engine. I really was shaking out of control and would not adjust out at all. Hard mounted and stable. I called Mike at RCS and we talked the day before yesterday and he was extreemly helpful and suggested the carb was inverted and he was right. I flipped it but still the engine ran really bad if at all. I called RCS and Andrea said send it in. I sent it with in a half hour. I am so glad to hear a company stand behind their product. I think I just got a bad one. The small plane I will install the 140 on would not last an hour shaking like that did. BTW, I had a ballanced mejzlik 18-6 on it and over a gallon of gas though it. RC Showcase seems to be a real good company.
HTH

Joe

Got the engine back from ZDZ two weeks ago. They tested it with a number of different ignitions and timing settings and could not find any problem. Sent it back to me with no modifications (that they would admit to). On the test stand, same prop, it did run smoother - putting my leg against the WorkMate at WOT did not result in intense pain as before.

Back on the H9 Cap, it was improved somewhat, but the tail group is still a shaking blur at mid and upper throttle. I suspect that it's harmonics at work, and the engine is as smooth as it's going to get. I'm going to try a 20 x 10 Bambula prop like Dick Hanson suggests - maybe the increased mass and stiffness will smooth it out. May also try an off-balance prop. In any case I'll put some tail brace wires on and fly the crap out of it until it breaks. I got the plane for $300 Cdn so it doesn't owe me much. I don't have the time or inclination to try soft-mounting it - it's a tight fit in that airplane as it is.

Anyone have any other suggestions?

KD

Take the refund, and get a Twin that's smooth. I've seen alot of servo gears that users have had to replace due to the singles...NO MATTER HOW GOOD ONE ***THINKS*** they are. The harmonic, and dynamic balance will *never* be what a twin will give you, and nobody that's in the know will dispute that. Go for more power, smoothness, quality of construction, longevity, and backing on a motor like this! These motors cost a small fortune! Why buy twice? I'd rather spend twice the amount on a motor than not be flying at all...that is why we buy these motors in the fist place. I've seen shakers, I've seen reliablity problems, and I've seen motors that would 'nickle and dime you to death'...it just ain't worth it...look around you. If you see a motor running maintence free, and trouble free, BUY IT! It will save you money in the long run.

Now for the naysayers...did I mention a brand? NO! So before you start a brand war, better think about what is running trouble free. I don't think it takes a rocket scientist to see that!

Well, I've got a smooth running ZDZ-80 single on a H9 Cap with over 300 flights on it. Hitec 5945 servos with gears that are fine. I run either Menz or Mejzlik props. Engine is mounted on aluminum standoffs with a slightly reinforced motor box.

My buddy has a new 3W-150 twin that vibrates more than the ZDZ.....strange but true.

Locally, we have two, models--weighing 11.5 lbs--1280 squares.
each model has a ZDZ40 rear exhaust on a tuned pipe - Lots of power - a little shake at idle but we have both been flying these models a lot --
If all singles were too shaky to use - these models would be junk by now
These models are built with only the strength necessary to stand extreme flight loads -no firewalls - no beefed up parts -anywhere.
rTwins are great too but the singles are also very smooth.

Dick Hansen: What is the name of the two models you are talking about? The ones with 1280 wing area. Thanks Capt,n

To follow up:

I got rid of the H9 Cap and put the ZDZ40 in a Kangke Texas Hurricane. When I went to fire it up for the first time I was mentally preparing for the worst - I expected to see the tail group shaking itself to pieces when I opened up the throttle. I was even scoping out the 'net for a 50cc engine to replace it.

Smooth as freaking silk! - I have 11 flights on it now and am completely impressed with the difference (and with how the Texas Hurricane flies - but that's another thread). I figure the harmonics of my H9 Cap must be completely wrong for this engine, because the current setup is even better that I expected. Maybe the engine box and frame disspate the vibration more effectively or something. Wow.

KD

the sympathetic vibrations in some airframe setups -are sometimes blamed on the engine - as you saw -
I have installed engines which shook like hell - till I switched props and adjusted the carbs .
The light 1280 sq in models I had - were my own design and there was no plywood in the fuselages except for a tiny engine mount pad and a slim x former for the gear .
I am flying a 1500 sq in Giles (own design - again no ply in the fuselge ) with a ZDZ80 single and guess what - no shaky ailerons or tail group - it weighs under 18.75lbs now as I even eliminated the spinner (4ozs).
These engines do run quite smoothly - when all is setup right .
just as smoothly (smoother ) than some twins I have seen -
I also have twin cyl engines - very smooth - but the singles -properlysetup should not cause any problems -

Just as a point of interest here, you need to be VERY careful with multi bolt prop hubs and wood propellers. It's very easy to apply too much clamping force to one side of the prop, this causes it to vibrate like crazy even if it's balanced perfect. If the prop is distorted end to end it will not track straight and cause vibs at lower RPM, if it's distorted side to side the relative pitch will be different and will vib at higher RPM. Paint the very edge of the tips two different colors, in the sun with the engine running up and down the RPM range you can eyeball it from the side to see if it runs true. Also if you are using a spinner, index it and balance it as a unit.

Use flat backplates on all spinners - this can insure that the prop aligns
The crowned backplate spinners are a real potential problem .
they were designed for simgle bolt setups -to maximize friction.