Ys dz185 zero
 

There has not been much information about the YS DZ185 ZERO engine, therefore I thought I should share my experience. The only difference to the nitro variant is the piston.

Initially the idle was too high, and transition not great. After consulting YS about the high rpm at idle they recommend to run the ignition on 2s-LiPo and increase the spark plug gap to 0.4 mm. It improved but still not fantastic.

But trying my new airplane with a YS Super Mount, voila, the engine problems were gone and the engine was running great. Changed the mount in my old airplane, and installed the YS Super Mount instead, this cured the engine problems I previously had with this airplane.

Clearly the movement of the engine has an influence on the pump, i.e. inertia load on the pump piston. The nitro probably masks this at idle and transition, and tolerate better the variation in fuel/air mixture. Any other thought/comments?

The props I use is APC 20.5x10 (Carbon) and APC 20x10.5. None of them feels “heavy”, so the power output is at least comparable to a YS175CDI nitro.

The fuel I use is 90% methanol and 10 % oil.

Valid in all sports: “Precision before power.” My feeling is that I do not lack any power with the ZERO, the precision in my flying is another matter.

Arnstein

Hi Arnstein,

The Zero has higher compression to compensate for no nitro, so I would expect the idle to be a bit higher.

What mount were you originally using?

Scott

Hi Scott,

I have used different types of Hyde mounts. I modified one mount adding an extra layer of rubber, it improved the idling a little. However, the to get down to 2K, both the Hyde Evo and the YS mount works, both fitted with hydraulic damper. Have not tried the Tubasakoubou-mount.

May be the higher compression causes the engine to idle at a higher rpm. The experience I have with the ZERO tells me the engine mount has a big influence on the idling and transition. A mount with a hydraulic damper I found is the way to go, get the same idling speed as with the nitro version.

My theory is that the vibration of the engine has an influence on the fuel pump. On the first versions the intake valve spring rate was very high, I experienced excessive cam gear wear. The 185 was the first (?) to have the same spring rate on both the exhaust and intake, may be the intake valve spring rate is a little on the soft side?

The YS 185 ZERO impresses me, same idling and throttle response. A little down on power, similar to a 175. The fuel cost very low, we pay a lot to get that extra power.

Best regards,

Arnstein

Very interesting input, thanks.

I have never used anything but YS supermounts, but I have seen other engines run, and ussually mine is smoother, your comparison and point of view shows some things to take in consideration.

An engine with a higher compresion will most likely need to run on a different ignition advance also I presume, is the ignition standard or "ZERO"? Just curious.

Regards

Hi all,
Just digressing a little I two had some issues with the softer intake valve spring on the 185 red CDI .
It allowed the pushrod to lift too far and jam the pump..

I have installed the TU mount but not yet flown with it ....will report back when I do.

Also according to YS the tube C to the injector should be changed regularly as it greatly affects the operation especially transition of the engine.
If it becomes too soft it will slide of the injector easily and it should be replaced.

Best regards

Mavros,

Which hose are replacing the injector one with? I just need to buy some fuel tubbing and I have not run my RED yet but will in a month. The hose replaces the spring on the injector and if it is too soft it might not pulverize well and too stiff will probably have bad idle and transition......


Regards

Hi Apereira,

As far as I know the tube is not replaced by anything different but has to be replaced if it starts to soften up.

According to YS normal fuel tubing is not suitable only the YS should be used.

regards

Yes,

That it was my understanding, but better ask....

Regards

I was having the same issue with my DZ 140 and replaced the tube with a peice of 3mm ID teflon. Haven't given it another thought since.

Not that I know anything... but my thought from a "mechanics' view is the tubing to the injector should be quite "rigid". The harder the tubing the less loss of fuel pressure from the tubing expanding with each pulse. Ideally, IMO, it should be a wire braid like a hydraulic hose.

ken

I doubt you are off base here Ken, my 140 runs more consistent with the ridged teflon tube. I feel,I was able to get a finer tune on it.

Hi Arnstein,

I have used the Hyde LR85 mount, (no damper), as well as the YS Super mount. I didn't notice any difference in idling or transition between the two, but I do think the Super mount is a bit smoother.

Interesting theory on the vibrations affecting fuel delivery. I haven't had any issues from this, but something to keep in mind.

In regards to fuel tubing, I'm not convinced that is a issue. I've used YS tube, Dubro medium tube and now Prather medium which I've been using for a few years now. Haven't had problems with any of them. But whatever works.

For the 185 Red and 200, the manual specifies that the carb to injector line, (tube C), must be a soft tube with 3mm ID and 5mm OD. This is to do with the new injector not having the check valve on top.

An engine with a higher compresion will most likely need to run on a different ignition advance also I presume, is the ignition standard or "ZERO"? Just curious.

Not aware of any special ignition unit for the ZERO. Had the same question myself.

Arnstein

I am not convinced that you reached the same conclusion if using 0% nitro. I guess you are running closer to 30%.

Arnstein

my my problem was that the tubing kept splitting. Even the Prather medium line.

This is different, it is a specific hose that works as a relief valve would, it is only on the injector, you would need to see it, it is not in any drawings and found only the 185 Red and later models.

Was it the pump to carb line or carb to injector line that was splitting?

Yes, pump to carb.

The Prather Medium is splitting? that's the one I have used for many years, but there's a hose clamp on that hose on both ends, do you have them installed?

Regards

Yes, I did have clamps at each end. The hose would split in the middle leaving about a 1/2” long split. Richard had warned me to keep an eye on that tube and replace when it started bulging. Never got to that point, I would get 3 to 5 flights and the tube would split in flight. Installed a Teflon tube and no issues since.

Oh, I see, good to know.

Regards

Hi Ken, the pressure is controlled by the regulator so any elasticity in the line between the pump and throttle body wouldn't cause a reduction in pressure but would cause an increase in the volume of fuel stored at that pressure. This would result in pump pressure being applied to the metering circuit and injector for a longer period of time.

It's not beyond the realm of possibility (pure speculation on my part!) that pressure in that line is supposed to remain for a while after the pump completes it's pressure stroke (a bit like filling up a bagpipe bladder) so the injector can continue to inject fuel as the valve is closing. After all, even fuel injectors in vehicles today can spend lots of time spraying at a closed intake valve under certain conditions. There may just be a Goldilocks zone of tubing rigidity for each engine??

It would be worth trying YS fuel tube.

Its now a case of " it ain't broke " so I have no real need to go looking for a fix. I have roughly 20 flights on it since going to the teflon tube and the engine runs very well.

I have measured the fuel pressure on the YS ZERO and at idle I read 0.8 bar. YS recommended to lean the pump 1/4-1/2 turn, will that drop the pressure from 1.1/1.2 to 0.8?
Anybody measured the fuel pressure on the YS ZERO?

Arnstein

I don't have a zero, but on my 185cdi 1/8th turn on the reg is around 70 - 80 kpa difference in pressure.

Are you sure it is not 7-8 kPa per 1/8 turn? If that is the case everything makes sense.
YS 185 nitro: 1.1-1.2 bar @ idle.
For YS 185 Zero, YS suggest leaning the pump på 1/4-1/2 turn:
1/4 turn gives 14-16 kPa ( 0.14 – 0.16 bar ) pressure reduction
1/2 turn gives 28-32 kPa (0.28 – 0.32 bar)
YS 185 Zero: 0.78 bar (1.1 -0.32) – 1.06 (1.2-0.14) bar
I am at 0.8, at the lower end of the range.
Would be interesting to hear if anybody else has any experience, I guess there will be some variation.

Yes, I am sure!!

14 - 16 kpa is NOT 0.14 - 0.16 bar. It is 0.014 - 0.016 bar.

You say 1/4 turn is 0.14 - 0.16 bar, (which is 140 - 160 kpa ). I said 1/8 turn is 70 - 80 kpa, so that's exactly the same as my readings.

Have you flown the engine at that 0.8 bar setting?

Yes, I have flown it several times with 0.8 bar setting. Still fine tuning due to ambient temperature change for like 10C to 24C.
Wrt unit conversions have you tried e.g.: https://www.convertunits.com/from/kPa/to/bar

Arnstein

Knowing what the actual pressure is, isn't really necessary. Flying is the only way to set the reg and needle properly. I start with the reg rich and lean it 1/8 a turn at a time until the transition is smooth.
Does the Zero need the reg adjusting due to temperature change?

I claim that the Zero is not more sensitive to temperature changes than the nitro version wrt pump adjustment. The pump adjustment and needle adjustment I have made is very minor and probably a mix of temperature and not being in properly tuned in the first place.

The pressure measurement “papaone” presented under the 200-thread is very interesting. And I agree it is not required for tuning a YS engine. However, if things does not turn out as planned, a very hypothetical situation though, I think it is nice if a pressure recording at idle and WOT can determine whether the pump is OK or not.

Arnstein

My 185cdi - 30% nitro, is 1.1 bar at idle. I haven't checked my 200.

Once the reg is set, I suppose having to keep richening the reg is an indication that the pump is worn.

I will try this week the pressure gauge for the first time, I think it will save some time to get to the close point where the final adjustment is in the air. I do my final adjustments in the air, I mostly adjust by sound and response.

Having used the YS-Zero this season here is my findings / thoughts:

· The engine produces max power on a very narrow needle range setting, compared with using fuel containing 20-30% nitro. Having said that, the power produced is enough for both P19 and F19. A get around 7000 rpm on APC 20x10.5 PNC, slight less on the APC 20.5x10 PNC.

· I use 10% oil (Molsyn 80K), the rest is methanol. For temperature mid 20s C and above, I find the best method to have a reliable engine is the cool down the fuel. As the attached graph shows the vapour pressure of pure methanol increase very rapidly, the 10% oil in the methanol will raise this curve somewhat.
The problem is in verticals like a stall turn, due to gravity the fuel pressure at the pump inlet drops, assume the distance between the tank and engine is 0.5 m, the pressure drop (approx.) is rho*g*h = 800*9.81*0.5 = 4 kPa = 0.04 bar. In addition the pressure drop across the clunk and the friction. In this flight condition (stall turn) it easy to get a vapour lock.
In this respect going back to the days with crankcase pressure in the tank would be a good idea.

· Measuring the pump pressure at idle I ended up at slightly less than 1 bar (0.96 +/- 0.04). It is possible to get the engine to run at a wide range of different pump pressure settings, but in this case it will not run properly at all throttle settings. Initially I had it at 0.8 bar, however, much less power at midrange.

· To obtain a good idle and transition the cam bearing need to be in a very good condition, more critical than running with a lot of nitro. Personally I would prefer cam bearings with a higher load capacity / stiffness. Compared with the non-DZ engine the load on these bearings have increased.

· Running cost very low, compared to any other power source.

On my engines only the piston is changed for the standard nitro version. For a “genuine” Zero, Yamada may have introduced additional changes, e.g. the carburettor body with throttle has a different part number compared with the non-Zero version.

https://cimg2.ibsrv.net/gimg/www.rcu...e7b375930a.jpg

Dz 185 cdi zero engine reassurance
 

The manual for the zero you may download from: Attachment 2262959

Anything on the outside of engine to confirm you know of?
I converted to the zero-version myself, replacing the piston only. So I do not know if there is any marking on the outside of the engine. To be absolutely sure you have to compare the pistons (nitro vs. zero).

Running nitro in a zero engine would not be good, right?

Some has used 5% nitro with success:

https://www.brueckner-aviation.com/e.../carf-valiant/

The manual for the zero only states 0% nitro.

If it is a zero, does Klotz oil have any blends of oil that are good for a fai blend?
Sorry not familiar with the Klotz oil.

Good luck!

Arnstein

Yes, Klotz has the full synthetic oil, do not use the blended as it has Castor in it 4%, use the Techniplate for helicopters or the full sinthetic one.