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RCAero JC Engines & YDA Engines

Old 01-09-2013, 08:33 AM
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Default RE: RCAero JC Engines & YDA Engines


ORIGINAL: R/C Addiction

It started up but only with the help of an electric starter. I can't hand start it anymore. As expected the compression is almost non-existent now. I got the engine tuned and it is putting out 6600 RPM with an 18X8 prop. Not too bad considering all of the carnage inside. It runs surprisingly well considering all the issues it has. I leaned out the low end as much as possible while still maintaining a decent transition. The tilt and slow down/die issue is still present so its not the reeds (tried two additional reed sets as well as the stock ones and replaced the stock carb with a DLE 30 carb). I do believe that I have tried everything within my abilities to remedy the tilt and slow down/die issue so the issue has to be inherent in the design. This will fly my Mud Duck MK II until I get a chance to replace it with a DLE 30.
Email me your shipping address and I will sent you some parts that I think will solve your problems.

Just pay pal me the shipping cost when you receive the parts

Milton
Old 01-09-2013, 08:38 AM
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Default RE: RCAero JC Engines & YDA Engines

E-Mail sent. Thank you Milton.
Old 01-09-2013, 08:43 AM
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Default RE: RCAero JC Engines & YDA Engines

Will get them out to you today.

The tilt and die is fuel puddling problem in the reed case, The reed I send you will have a plastic wedge in one part of it that will not let the fuel puddle.

Milton
Old 01-09-2013, 08:45 AM
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Default RE: RCAero JC Engines & YDA Engines

I will give em a try and report back.
Thank you for the parts...
Jeff
Old 01-09-2013, 05:31 PM
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Default RE: RCAero JC Engines & YDA Engines

ORIGINAL: R/C Addiction

The tilt and slow down/die issue is still present so its not the reeds (tried two additional reed sets as well as the stock ones and replaced the stock carb with a DLE 30 carb). I do believe that I have tried everything within my abilities to remedy the tilt and slow down/die issue so the issue has to be inherent in the design.
Hi, seriusly read my comment above. By rotating the carb 180° and mount it this way (you need to modify the pump tubing from the crank case to the carb)
Look at the design on other brands like DLE, DLA etc. they all have the carb mounted the way I mentioned. Also the first DA 50 had this problem with the first series and guess what they changed later: They rotated the carb 180°.
:-) Different reed blocks were tested many times but only improved a little bit but never fixed it completely. I don't believe this theory because the symptoms are also there immediately after you come from high RPM's down to idle. There is no change for fuel pools in this short amount of time.

Andy
Old 01-09-2013, 06:20 PM
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Default RE: RCAero JC Engines & YDA Engines

Andy,
If all else fails I will give that a try. It will involve having to relocate the throttle pushrod which would be a pain but it is an option. Thanks for the tip.
Jeff
Old 01-10-2013, 01:35 AM
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Default RE: RCAero JC Engines & YDA Engines


ORIGINAL: R/C Addiction

Andy,
If all else fails I will give that a try. It will involve having to relocate the throttle pushrod which would be a pain but it is an option. Thanks for the tip.
Jeff
Just do a dry test w/o changing the linkage and see if it helps. That’s the way how I did it. Just play with the throttle directly on the carb. I put a little set screw in, to adjust the RPM, you can't use the original screw any more with the Carb turned 180° around because it hits one of the engine stand offs.
Old 01-12-2013, 11:45 AM
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Default RE: RCAero JC Engines & YDA Engines

So Milton sent me some parts to fix my engine and they arrived today. Thanks again Milton! You know you didn't have to do that. So a bit later today I am going to replace the damaged parts with the parts that Milton sent me. He also provided a reed valve assembly with a spacer/wedge that should solve the tilt and slow down/die issue. I will take pictures and post them as I progress.
Old 01-12-2013, 12:24 PM
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Default RE: RCAero JC Engines & YDA Engines

Milton,
I just received the parts that you sent. Thanks again for doing that. I also sent $7.00 to your e-mail address via Pay Pal to cover the money for shipping. One question though…the wedge for the reed valve assembly…should the reed block be mounted as per the stock configuration (pulse line fitting mounted with the fitting at the bottom of the engine) or toward the top of the engine? I have my engine mounted with the jug upright in the airplane. I was just thinking that the wedge might need to be mounted at the bottom, in my case, if it’s really a fuel pooling issue causing the problems (which would mandate mounting the reed valve assembly with the pulse line fitting pointed up because the wedge and the fitting are at opposite ends of the reed block.)
Old 01-12-2013, 03:20 PM
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Default RE: RCAero JC Engines & YDA Engines

Email sent.

Milton
Old 01-12-2013, 04:48 PM
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Default RE: RCAero JC Engines & YDA Engines


ORIGINAL: R/C Addiction

Milton,
I just received the parts that you sent. Thanks again for doing that. I also sent $7.00 to your e-mail address via Pay Pal to cover the money for shipping. One question though…the wedge for the reed valve assembly…should the reed block be mounted as per the stock configuration (pulse line fitting mounted with the fitting at the bottom of the engine) or toward the top of the engine? I have my engine mounted with the jug upright in the airplane. I was just thinking that the wedge might need to be mounted at the bottom, in my case, if it’s really a fuel pooling issue causing the problems (which would mandate mounting the reed valve assembly with the pulse line fitting pointed up because the wedge and the fitting are at opposite ends of the reed block.)
Jeff, can you take a photo please, I'm just curious to see the new design.
@Milton, is the new reed block an original part from JC engines or second source (which is maybe better than original)?
Old 01-12-2013, 05:04 PM
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Default RE: RCAero JC Engines & YDA Engines

I assembled everything already....and forgot to take pictures...but...after talking to Millton a little bit more, I determined that I need to take it apart again and change the configuration a little bit. So this time I won't forget to take the pictures!
Old 01-12-2013, 09:27 PM
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Default RE: RCAero JC Engines & YDA Engines

Well I took apart the engine yet again and now have the reed wedge in the correct location. The engine in my airplane (Mud Duck) was installed with the jug at the top of the aircraft. Usually a gasoline engine is installed with the jug pointed down. The engine was purchased (stock configuration) with the reed wedges filling in the space on three sides of the reed, the top and both sides. If the engine had been installed with the jug pointing down, the stock wedge location would have been correct, filling in the space on the bottom and the sides not allowing the fuel to pool at the bottom. I couldn't relocate the pulse tap on the top of the reed block because the cylinder wouldn't allow it due to space limitations. I therefore drilled a new pulse tap location hole at a 45 degree angle and plugged the old tap hole with a screw. I will have to wait until tomorrow to see if the modification makes any difference. I hope that I didn't confuse anybody too bad. I have attached several pictures to help.
Jeff
Old 01-12-2013, 09:29 PM
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Default RE: RCAero JC Engines & YDA Engines

Pictures...
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Old 01-13-2013, 01:41 AM
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Default RE: RCAero JC Engines & YDA Engines

Oh yes, w/o the pictures I had no clue what you talking about
Ok I thought also you had the jug installed downwards.
But now it's clear why one reed broke, it was the only one right? By blocking the 3 other the one had to move to much-> too much bending for it.
I didn't expect that simple wedge design. You said they were installed from the factory? I don't have one installed. All four reeds are working.
So far I completed only a short test run and it seemed it improved the idle performance to satisfaction.
When the weather is getting better I will report after the test flight.

BTW: when you look in the OS GT33 [link=http://manuals.hobbico.com/osm/gt33-manual.pdf]manual[/link] you see the same reed block design (see exploded view) which used for the EVO28, so I wouldn't block any of the reeds. It decreases the air intake and I would expect a loss of power too.
Based on your pics, you installed 2 wedges, one at the bottom and at one site, correct? The two remaining have still to much to move during each stroke and may will break again. This is just my feeling.
But let's see if it fixes the annoying idle issue, good luck.

Andy
Old 01-13-2013, 09:15 AM
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Default RE: RCAero JC Engines & YDA Engines

Yep the reeds were blocked on three sides as I received it from the factory but since my engine was installed with the jug up the modification wasn't doing anything. I believe you are right about the reason for the reed breaking. I will try this arrangement and see how it runs. I will probably start it up today and see how it runs. I certainly have a bit more compression after I installed the jug and piston I received from Milton. The wedge I received from Milton only blocked one reed at the bottom of the engine so I made a judgement call and modified the wedge I had so two of the reeds will be constricted. If it lasted this long with three of them blocked I should be able to fly my Mud Duck for a while until I can replace the whole engine.
Old 01-13-2013, 12:28 PM
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Default RE: RCAero JC Engines & YDA Engines

I started up and tuned the engine. I am getting 7000 rpm with an 18x8 prop and the engine seems to run pretty good but the tilt and slow down/die issue is still present...with one change. When I received the engine and ran it, whenever the mud Duck touched down the engine would immediately drop RPM or quit in addition to the tilt and slow down/die issue. Now the engine doesn't do that. I bounced the model on its landing gear while the engine was running and there wasn't any RPM change. I wanted to thank Milton again for sending the parts as now I will still be able to fly the model but the engine will still need to be replaced. As I have said before the Mud Duck utilizes an abnormally high idle which will allow me to fly with this engine but the engine won't go into another model.
Old 01-24-2013, 11:09 AM
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Default RE: RCAero JC Engines & YDA Engines

Milton, I'm upgrading my fleet to LiFe batteries. Did/does the JC 28 ignition support operation up to 6.6v?
Old 01-24-2013, 12:53 PM
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Default RE: RCAero JC Engines & YDA Engines

All in how old the ignition is.

Look on the ignition and it should tell you, If it say's 4.8 to 6 volts stay in that range.

Milton
Old 01-24-2013, 05:23 PM
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Default RE: RCAero JC Engines & YDA Engines

Thanks Milton... yes, it says 4.8 - 6v. I'll use a dropping diode or two.
Old 04-26-2013, 03:18 PM
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Default RE: RCAero JC Engines & YDA Engines

Hi Guys,
I have a YDA-56 engine in my 1/3 Cub. I found that one of the mounting lugs on the back cover is broken off. Not quite sure how this happened. I had nosed the Cub over in high grass once and broke the prop, maybe it happened then. Anyhow I need a new back cover, are there parts available for this engien anymore?

Thanks!!
Anthony
Old 04-26-2013, 03:22 PM
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Default RE: RCAero JC Engines & YDA Engines


ORIGINAL: WacoNut

Hi Guys,
I have a YDA-56 engine in my 1/3 Cub. I found that one of the mounting lugs on the back cover is broken off. Not quite sure how this happened. I had nosed the Cub over in high grass once and broke the prop, maybe it happened then. Anyhow I need a new back cover, are there parts available for this engien anymore?

Thanks!!
Anthony
Anthony,

If you can get your hands on a back plate from a JC 53cc, I believe they are the same part

I hope this helps
Old 04-26-2013, 03:42 PM
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Default RE: RCAero JC Engines & YDA Engines

Thanks for the tip , I will see what I can find.
Anthony
Old 04-26-2013, 04:06 PM
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Default RE: RCAero JC Engines & YDA Engines


ORIGINAL: WacoNut

Thanks for the tip , I will see what I can find.
Anthony

I have a couple rear crankcase that i think will work.

Take a picture of your so I can see it close and measure the center to center bolt pattern that hold the two cases together.
Old 04-26-2013, 04:38 PM
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Default RE: RCAero JC Engines & YDA Engines

Hi Milton,
Here is a couple pics.

The distance between the holes nearest to the cylinder is 2.7" and 2.1" between the other 2 holes. The distance between the sets of holes(top/bottom) is 1.925". I used a set of digital calipers and these dims are pretty close.

You can see the broken mounting lug in the pics.
Thanks!!
Anthony
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