OK, I'm getting frustrated with this one . . . I just picked up used 140DZ. The thing is not running right in the midrange, and seem slightly down on power (8800RPM with a Mejzlik 16X12 on Powermaster 30% DZ blend). Compared to my great running 160DZ, the 140 seems vague on high speed needle setting. Mine will run about the same at full throttle anywhere from 1-3/4 to 1-1/3 turns out. The idle is solid, but the midrange is soggy, and it has quit 3 times in the air at part throttle, the latest tonight on the second 45 line of a reverse cuban.

I ran it on the ground, and noticed there a lot of bubbles in the injector line at part throttle. Maybe the pump is bad?

The 140DZ has a very broad HS needle as you said. You should run it toward the leaner side of the range...maybe 1-1/3 to 1.5 open. If its rich in the middle then you can lean the pump slightly. Say 1/8th turn CCW on the pump screw.

I don't know that its a bad pump.

Turning a 16-12 at 8800 on 30% DZ fuel not down on power. I used the APC 16-12 at it turned about 8600-8800 on 30% heli. So you are in the right range.

If your pump was bad it would not idle well.

It could be cutting in the air from too rich....also when was the last time you changed the plug?
This can show similar problems. rich mid rnage and dead sticks....

Change the plug first then look to leaning the pump a little. If it gets detonation in the middle and gets that hollow sound then cut it off and richen the pump back up.

Troy Newman
Team YS

The plug is a new OS-F, I put it in after it quit for the second time at the D4-D5 shootout. D5 DZ wizard JH worked on it Saturday night, It ran like a monster on Sunday, HS needle out 1-3/4. I went out tonight to practice (lord knows I need it) set the same as it was for rounds 5 and 6 in Muncie and it quit on the opening reverse cuban 8 in Masters. I tried setting the HS needle but it seemed to have no effect on midrange. There is slight stumble going from idle to full throttle, I figured the pump was lean, but richening it did not help the midrange.

I miss my 160DZ. My home field is not kind to unexpected dead stick landings.

why didn't you grab me at the Shootout and I could have helped. Its very hard to help via the internet....yet I was there. I was screwing around with the boys and not really paying close attension to other guys flying. I know Bob Kane had lots of problems. I offered him a well tested and run 160DZ that was sitting in the box all weekend long. Instead he fought through several dead sticks. I offered the motor each time and he refused each time.


In any case as I said above the HS needle on the 140's is pretty broad and it will show the little to no change that you are talking about. As I said above THIS IS NORMAL. The HS will have little affect on the midrange to your ear...but it can if too rich on the HS cause the engien to load up and die in the mid-range. The HS needle works at all the settings not just the top end. This is why you should run in the leaner spot of that wide band you mentioned.

Also I mentioned above that you should lean the pump. The fact that you richened it and it didn't help is a sign it could have been rich to begin with.

I think you should lean the pump. CW about 1/4 turn and see if the midrange cleans up. This is what the pump does it controls the idle and transition though the mid range. So if you say its slobbery in the mid range then the pump is currently too rich.

Troy Newman
Team YS

Hi Troy,

I have found that bubbles in the injector line can mean a worn plunger in the pump, and its easy to test
if this is the case.

First remove the pump assembly from the engine complete with the two half push rods,
Get two pices of fuel tubing of sufficent length with a clunk attached to one end of each piece
and attach the other end of the tubing to the pump fittings.
Have two containers with some fuel in each container and drop the end with the clunk attached in each container.

Holding the pump assembly in one hand, and with the other hand hold the push rods between thumb and finger,
move the push rods up and down in the pump as fast as you can, the pump will start pumping fuel from one container to the other.
You may have to manually fill the lines and pump with fuel if it won't self prime.

While you are pumping fuel watch the fuel lines.
If the plunger is in good condition there will be no air bubbles in the fuel lines, if there are bubbles in the out side of the pump, then the plunger, and or, pump body is worn.
If you have bubbles on the in side to the pump then you have not set up the test properly.
I've found its usually only the plunger thats worn, and a new plunger is very cheap.

Reasemble the engine and test run, no bubbles in the injector line.

Team Crossman

Good Tip thanks.

I now that a sign of a bad pump is poor idle. It idles fine then unpredictably just shuts off. Not a hard thump just it can idle for 3 mins solid and then just no warning cuts off. Then it doesn't want to start. Let it cool and set for several minutes and it starts up and runs again like a champ and then out of nowhere just zip its off and won't start back up.

I have only had one pump go bad in my time with the DZ engines and that was many years ago. In fact I believe it was my first proto type 140DZ.

I have a pump here that I swapped out with a guy a couple years ago that we thought was bad at the time. Pump from my Backup engine and his problem were solved. I guess its time to play with it and find out why its bad.

Troy Newman
Team YS

Troy, I just realized my real name is nowhere on the post, this is Bob Kane. Here is my brief history of this motor:

- Purchased from MA, fellow FAI pilot at Muncie. He said the motor had not been run since return from YS service.
- I installed it in the plane and ran it briefly Friday night. It ran ok, but there was a little fuel residue in the valve cover.
- Saturday morning, you suggested I change out the dark blue tubing on the motor with fresh fuel tubing. I did, and assumed that must
have been the source of the leak.
- The motor quit after 3 or 4 manuvers in my first round. When I got the plane back to the pits, the top of the motor was wet. I pulled the valve cover and found the gasket was cut. I put in a new gasket and assumed the problem was fixed.
- Motor ran ok for round 2
- Motor quit again a couple of manuvers into round 3. I did not die suddenly, it kind of coasted to a stop, always after low throttle
setting.
- I missed round 4, I could not get it tuned correctly.
- JH worked on the motor, and found the intake valve setting to be too tight, so the assumption was it was heating up during flight and
causing a loss of compression, consistant with the way it was quitting.
- JH also replaced the regulator diaphram with the newest version.I installed a new OS F plug.
- Reset the regulator to flush and needle out 1-3/4 turns, the thing ran great. Nice linear throttle, good power.
- Motor ran great for rounds 5 and 6

Which brings us to yesterday.

I am going to replace the pump body and upper pushrod to see if they are the source of the leak. I'll post the results.

Ok...that makes more sense. I really didn't see anyone having torubles but I know yours did. Every time it seemed you found the problema nd it should have been fixed.

Little things like a cut valve cover gasket and so on...

Another thing to consider is cooling. It was fairly mild in Muncie yet if it was Hot when you got back home it could be a cooling issue. The coasting to a stop on throttle up is sometimes a sign of over heating.

The tempattion you have is probably good as far as coolign goes. Just make sure raw air is hitting the pump. Some folks have lined their cowl with foam from the YS engine box. The cut out basically ducting to direct air flow right onto the engine. The YS engine box foam is so good for this as it is light...and if the engine hits it not damage will come to either part.

As temps heat up you may want to look at this if you have trouble with heating. A buddy down in Georgia Bryan Kennedy had some problems with a 140Sport and 140L this spring with over heating and we thought the motors were bad. Turns out he was just flying on 90 deg days with high humidity. I know how the rest of the country gets with the humid weather. Its tough on engines. Here in Phoenix witht he temp today at about 110deg I know what temp problems look like. I would say in Muncie it was probably the best weather I have seen there on the weeend. Sunday night we stayed and flew till dark. The air was so awesome. Rusty and I were practicing the Finals sequence and unknowns.

Troy

Troy.

I hate to but into a thread but my 140-sport seems to have some of these symptoms too.

Sometimes it will appear to coast to a stop and sometimes it will stop rather abruptly too. There is air bubbles in the fuel line from the regulator to carb line and because the motor is inverted the clyinder head and valve cover are wet with fuel from carb I think.
I too am getting rather perplexed with the motor , and, where I fly here in the UK no-one else has a YS so can't help with tuning it either.
It has good rapid transition from idle to full power and is taching at 8700 on a 17x6 apc prop and 20% MT Yamada fuel.
The idle needle is almost all the way out and yet the idle is rich and will choke up after 45 sec to 1 min.

Any light to shed on it !!!

Aeroboy the 140 Sport and the 140DZ are totally different animals. The way the engines work is totally different. So the problems are not the same although the symptoms could be similar.

On your 140 Sport...The low end air bleed screw if it is open more than about 2.5 turns its not doing anything. In fact this may be where you leak of fuel is coming from. The idle screw you are referring to only controls the size of the hole in the throttle barrel for air bleed. If the hole is full open it doesn't matter how many more turns you twist the screw open the hole is only one size max. If the adjustment is such that the hole is not big enough then the regulator is too rich and needs to be leaned out.

It could also be spitting from the carb if the regulator is set too rich.

If you lean the regulator a little it will be the air bleed screw back into a working range. Say 1/4 turn in CW on the regulator screw should get it closer.

It is common on the pressurized motors to have tiny bubbles in the line from the regulator to the carb. The reason is the fuel before the regulator is under pressure and when it goes to the carb it is allowed to expand, and doesn't sit under as much pressure. This means any tiny tiny tiny bubble will expand in volume.

Lean you regulator out a bit and try it. This should help the load up on idle.

Troy Newman
Team YS

I picked up some new pump parts, Central was back ordered on the pump body. That pump plunger looks an awful lot like the cam follower. I'm replacing the pump plunger, upper pushrod, carb O ring, and pump seal. The pump diaphragm was already replaced. The new parts will be installed tomorrow, I'll report the results.

Well, no good. The engine ran strong and idled well, but a couple of manuevers into the Masters sequence it died. When it quits it is usually after some idling on a downline, the prop is still turning, it just won't throttle up and dies. On the ground the motor just does not sound right in the midrange. The RPMs will sometimes vary with no change in throttle position. I started with the pump regulator flush, but the motor hesitated going from idle to full throttle, and it would vary in RPM in the midrange, suggesting it was lean. I tried turning in the screw in 1/8 turn increments until it was too rich in the midrange, all to no avail.

When I first flew this plane last season, I was flying a 140DZ I bought from Tim Jesky, Andrew's alpha motor before he went electric. It was fresh from YS service. It behaved exactly the same way. I tried a lot of different remedies including a header tank, running it lean, playing with the regulator, all to no avail. The crank failed and that is when I purchased a new 160DZ, which ran like a clock once I got good pump for it. (When new it would blow the fuel line off the throttle body, the regulator was stuck closed. The bore of the regulator body was not machined properly).

The 160 ran great in this same airplane until the rotory valve failed a couple of weeks ago. I doubt the problem is related to the tank or cooling.

These motor are relatively simple. No adjustment except main needle and the pump regulator. My guess is something is wrong with the pump, but I have not figured out what yet. I am suspicious of the bubbles I see in the line going to the injector at part throttle. I also don't trust bench running. The motor will run all day long on the bench, as would my 160DZ with the bad regulator housing.


To summarize what was changed:

Pump Plunger
Pump regulator diaphram
Upper intake pushrod
Throttle Barrel O-Ring
Cleaned up Valve cover gasket surface
Leak Free gasket on valve cover
New intake valve adjuster (original was stripped)
New OS-F plug

The parts in the pump NOT changed:

Push me-Pull me valves and springs
Pump Body
Regulator Spring
Regulator O-Ring



From the basement of YS Hell . . . . . . . . . electric is starting to look better . . . . . .

Sorry to butt in again but it seems to be temperature related and you say don't sound quite right at half throuttle, which reminds me of a new engine I serviced a few months ago.

The problem was tracked down to a air leak between the chambers in the carby base, which only became evident as the engine temp rose.

Refacing the carby base, insulator block and backplate cured the problem.

Maybe its worth a try.

Team Crossman

Thanks I'll take a look at it. I have not removed the throttle body or back plate yet, been focused on the pump.

Well XMANS, I think you are on to something. I pulled the engine and checked out the carb/phenolic spacer as suggested, while I can’t tell if it actually leaked, the carb body needed to be honed, there was a slight low spot in the original machining and the phenolic insulator was definitely distorted. The phenolic insulator could have slowly warped just sitting there. I honed the carb body and insulator on some 400 grit paper to make everything flat. The screws holding everything together were tightened to different torque values, I used my trusty click-stop torque wrench to reassemble it to reasonable and equal torque values.

Weather permitting, I will bench run it tomorrow, but flying will have to wait for now.


BTW, love your country. I was in Sydney last July and had a blast.

Cool, that sounds like it could have been it.

I have been seeing this too on the carb bolts lately where an overly tightened carb body has warped the carb and the phenolic plate. Usually it takes a pretty severe over torquing of the bolts to cause this but maybe the engine sitting for a long time and then getting hot and cold hot and cold it just twisted and stayed put.

Let us know how it works out. I'm counting on it getting taken care of for you. Sucks to have engine troubels and not know where to go to find it.


Troy Newman
Team YS

Glad you enjoyed your self down here last year, pitty you didn't get to Melbourne,

Hope it has cured your problem, and I think your right Troy about the over tightning bit,
I do a lot of refacing to the insulator and the carby base's down here, or throttle body as I should call it.
Too much past experiance working on car engines.

And talking of overtightning, I just got a 120 running for a customer and was going to pull the head off to replace to O rings but quickly changed my mind, there was no way I was going to get the head bolts out with out doing damage, so decided to let sleeping dogs lie.
I don't want to drill out bolts unless I really have to.

I'm beginning to have second thoughts about taking on the Team Managers job for Argentina, but she'll be right.

Team Crossman

The bench runs tonight were encouraging. Ran strong, good idle, good midrange. It still had a slight hesitation going from idle to full throttle so I richened the pump 1/2 a turn from flush and it runs great. 9120 turning a 16X12 and would idle at 1500RPM, at least on the bench. All throttle positions were solid, no wandering RPM.

I did not have a new set of gaskets for the DZ so I used an old style Leak free for the throttle body and reused the carb spacer gasket. I'm going to hold off flying until the new gasket set gets here from Central Hobbies.

On the road again, I mean, in the air again, good to hear, happy flying.

Team Crossman

Well, no good. Motor quit after take off and a couple of lazy loops. Same symptom, everything fine for a couple of minutes then it would not throttle up after the backside of the loop.

So I'm baffled . . . . . something is fundamentally different between the 140 and the 160. When I initially started flying this plane I had a used-but-fresh back from YS service 140DZ engine in it. It would quit in exactly the same way. I was told I was running too rich, so I ran it on the ragged edge of lean, only to have the big end of the crank break off. YS made me a deal on the 160, and it ran like a clock, never missed a beat. The 140 won’t run reliably, the 160 never quit. Same tank, pickup, throttle servo. Since I have had the opportunity to thoroughly go over the YS parts list, I know the pump assemblies are the same, so that is probably not the problem, the throttle body and related parts are the same. I find it hard to believe any other internal part would cause this problem. The only obvious difference is the injector check valve on the 160. The 140 does not have one.

Why does the 160 have the check valve, and could that be the issue? Would the 160 check valve fit the 140?

Back to the bench.

I'm going to assume there is a heat issue. I don't know why the 160 would not suffer the same problem, unless it is more mildly tuned. I'm going to add air exits to the firewall and route them out the back of the cheek bulges on the Temptation. Probably a couple of evenings work, I'll post the results.

Bob,

Use foam from from the YS engine box. You can use 5min epoxy to fix it to the cowl. Make ducting that goes right to the front of the engine directing it to the head. Specifically as much of the pump and pushrod tubes as possible. The idea is to make the air from the front only go through the engine and not allow it to bypass around. Any spot bigger than 1/4" it too much gap. This will help tremendously with cooling. The 160 doesn't run so hard, and it has less metal mass to heat soak when running. The thinner the metal the better the heat transfer. Also you were running your 160 in cooler temps last fall and this spring.


If you pump is not 100% exposed....It needs to be. I got home and its been over 115degs the last week. I flew a couple days ago and then added some foam to my model it works pretty well. I did this last year also.

Next thing is your pipe. Not sure what pipe you are using but if its an ES pipe I would bet money a baffle is blown up and is plugging it up. I ran the ES pipes and could get almost a year out of them in Colorado when I first started with them. They are good and light and the sound is excellent. However in AZ I was down to about 15 flights on a new one and could plug it up or blow it up. If they didn't blow up in 15 flights they would start to leak. I was the only guy having this problem so I just took it that I was idiot. I switched to hatori, and Asano and didn't have any trouble after that. Now I just run the Hatori stuff. Saves me head aches in trying to decide if the pipe a problem or the engine. I struggled with engine problems for 6 months in the AZ heat and finally found out it was the pipes.

Depending on the fuel you have used in the past too it could be that an older pipe could have some carbon build up and it would cause more restriction and make the engine run hotter. This can happen over time and you would not notice it...Just that an engine goes bad...and you replace it then that one doesn't work for beans and you start to question why are you having troubles when its not the engines fault. Its a combo of colling and a restricted pipe.

Troy Newman
Team YS

Thanks Troy . . . . the pipe is a Hatori. The 160 ran in the middle of summer, I started flying it in July, so the temp was hot. This is contributing to the sense of "what the heck could it be?". When I had this issue with the previous 140SZ, I tried a header tank, did not help. The 160 did not need it.

The 160 ran last summer on the same pipe? Then it could have build up since last summer?

It could be something inside the Hatori Pipe...Do you have another to try...or just run the engine with a header only to see?
My thinking is it could be carboned up or blocked.

What fuel? is the question if its been Cool Power all along then its not likely the carbon build up. I have not seen it in running the CP since 2001. But I know lots of guys last summer had an issue with a specific fuel.

Just curious if it was that?

Troy

I did not burn a lot of fuel, maybe 6 gallons.