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RCAero JC Engines & YDA Engines

Old 09-21-2011, 05:10 PM
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Default RE: RCAero JC Engines & YDA Engines

It is the little issues such as engines regularly leaving the factory with known faults and continuing to do so after the factory has been notified of the issue. that decides if a brand is worth having.
That manufacturer did just that - wrong reeds, unblocked internal pulse ports, bad carb pump diaphragms etc. Basically a decent enough engine but in a market size where many of the "gas newbies" head to, such antics are pretty unfair to the distributors and the customers.

JC is not the first company to have done such things and won't be the last. I often draw blood when I bite my tongue (fingers?) so hard when I see the other problems repeating themselves over and over on a couple of other "budget" brands. Tehn to see some of the distributors of those brands proceeding to give inaccurate information it really galls me.
Such as:
"Nickelite" bores (Nickelite is a Tin based Babbit - definitley not a good choice for a bore lining - especially as the bore in question is actually flame coated chrome)
Bearing fits listed as "tight" (yeah - corrosion will make them tight too - what about an actual engineering fitment?)
Engines sent in then sent back with a different set of problems showing (that guy sent his in for a carb problem - got it back with a reed problem).


Those examples do not refer to any of the brands in this thread and do not refer to one manufacturer - they are just recent examples.
Old 09-22-2011, 03:48 AM
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Default RE: RCAero JC Engines & YDA Engines


ORIGINAL: aussiesteve

Hey ceerb1
What you are experiencing is the classic JC28 ''tilt and die'' issue.
The most common cause of it is the carb fuel pump diaphragm needs replacing.
D10 WAT Kit from Walbro (try your local mower shop) use the Tan or the Blue diaphragm.

If you take the carb off to do it, do not overtighten the bolts when you put it back on. There is no real need to remove the carb though.

Many of the JC 28's were delivered from the factory with faulty (probably old stock and dried out) fuel diaphragms and they continued to be delivered that way until the stocks of the engine ran out.
This now makes sense to me... I had wondered about the diaphragms but the engine is just reached a use of just 15 liters of fuel! its still pretty "new" but definitely passed the early break in stages and it is something this engine has always done.. and being new I "trusted" the diaphragms.

Ordering 2 D10 just incase!
Ebay to the rescue as always!
Old 09-27-2011, 12:25 PM
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Default RE: RCAero JC Engines & YDA Engines

Ok, blue pump fitted... the "grey" or fibre one didnt have the little "flaps" to cover the holes... bit strange!

I also replaced the larger diaphragm as well while I was there.. makes sense..

Now just to see if tomorrow after work I can fire it up at the warehouse and see if its cured (at last).

If I am changing to a stiffer pump, can I expect to need a re-tune? My brain tells me it will now be lean... am I thinking right?
Old 09-27-2011, 02:33 PM
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Default RE: RCAero JC Engines & YDA Engines

Yep, Those kits cover a number of different carbs hence the amount of bits you don't use.

Whenever anything is changed in a carb, it is always a good idea to recheck your tuning. More than likley it will be slightly richer due to the new diaphragm working well.

It shouldn't take long to do.
Set the high for max RPM
Set the throttle to 2500 RPM (and leave the stick at that point) then lean the low needle until the engine revs start to drop or the engine doesn't speed up any more
Recheck the high speed for max RPM
Go back to the low and adjust to give a crisp transition (Usually will need richening).
go fly and adjust as required according to flying requirements.
Old 09-29-2011, 09:23 AM
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Default RE: RCAero JC Engines & YDA Engines

Ok.. getting a little tired of this!!


Replaced this pump with the blue one..
Just waited till after work tonight to head to the flying field.

WELL.. when I tuned the low end so that there was no rpm drop, the engine would cut when I raised the throttle.
So I'd richen up the low and it would accelerate cleanly.... and I lift the tail and the RPM drops!?!?!

Guessing its just not a great engine!


More urgently.
if you were to perform a tumble and cut the throttle and the engine were to cut at THAT moment.. (sounded like it slowed down, giving it gas didnt save it in time) would that be too rich or too lean ??????

Getting "nervous" as I am ment to be flying in a public exhibition on saturday and i'm just not trusting the motor or my tuning skills!

Maybe I should get a DLE 30 ... or go eleectric...
Old 09-29-2011, 10:40 AM
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Default RE: RCAero JC Engines & YDA Engines

Here are 2 photos of the sparkplug..


https://picasaweb.google.com/1066371...eat=directlink
Old 09-29-2011, 11:35 AM
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Default RE: RCAero JC Engines & YDA Engines

Hi Ceecrb1,
Check your inbox, PM sent.

Paul
Old 09-29-2011, 11:39 AM
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Default RE: RCAero JC Engines & YDA Engines

yeah just seen it. many thanks!!!!

out of desperation, I have tried "splinting" the spark wire to a small wooden dowel to keep it ridgid incase it has a bad section or socket etc.

"got" to see if I can get this fixed tomorrow night or I miss out on the public display on sat lol.. would be a shame but NOT going to risk the public (and to a minimal extent plane) with an unreliable engine.
Old 09-30-2011, 03:53 AM
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Default RE: RCAero JC Engines & YDA Engines

I've got a JC28 in an MX2 that has been running very well for a couple of seasons now. Last weekend, about two minutes into the flight, it just quit. Tried one more flight and again a couple minutes in it quit. All of the plumbing was good. The fuel line up to the engine was full. My first guess is that the ignition went bad. Is there any way to test them other than replace with a good one? Where is a good place to purchase an Rcxcel ignition? Thanks.
Old 09-30-2011, 04:46 AM
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Default RE: RCAero JC Engines & YDA Engines

You posted that all your plumbing was good but one way to really test it is to fill the tank and then remove the fuel line that is connected to the carb and remove the fuel from that point. then if all the fuel is removed you know for sure there is not a problem with your fuel lines.

Milton
Old 09-30-2011, 03:09 PM
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Default RE: RCAero JC Engines & YDA Engines

How about your bat switch and or your optikill. If they go bad due to vibration will cause the same problem. Bypass one or both and see if the same thing happens. Just my 2cents worth as I have been there.
Old 09-30-2011, 03:52 PM
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Default RE: RCAero JC Engines & YDA Engines

Was wondering how many are have the Tilt and Die issue with the Jc 28 with the WT 805 carb?

Is this common or random occurrence?
Old 09-30-2011, 05:50 PM
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Default RE: RCAero JC Engines & YDA Engines


ORIGINAL: meanrc

Was wondering how many are have the Tilt and Die issue with the Jc 28 with the WT 805 carb?

Is this common or random occurrence?
Many


Common

PM Sent as to the reasons

Diaphragms (old stock supplied)
Wrong reeds used
Crankcase warpage over time (Poor metallurgy)
Old 10-06-2011, 02:25 PM
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Default RE: RCAero JC Engines & YDA Engines

Hi aussiesteve

I have my YDA-56 installed in my TopFlite Giant P-51 , it,s running well and I have no complaints . It is running rich , doesn,t bother me at all .

I do have one question though

It starts vey well , but when it,s about to start up , it has a tendency to try and start backwards , and stops abruptly . Would this be an indication that the timeing is to retard ?

Thanks for looking in
Michel


Old 10-10-2011, 05:56 AM
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Default RE: RCAero JC Engines & YDA Engines

Very simple fix that will take a few minutes.

Steve
Old 10-10-2011, 01:34 PM
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Default RE: RCAero JC Engines & YDA Engines


ORIGINAL: derjager

Very simple fix that will take a few minutes.

Steve

Hi Steve

Thanks for looking in .

And what , " very simple fix " , would that be ? I,ve checked the timing and it is , " spot-On " TDC 9.7mm .

Michel
Old 10-10-2011, 04:51 PM
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Default RE: RCAero JC Engines & YDA Engines

Hey Michel I've never heard of a timing as you state. How many degrees would 9.7mm be. If your engine runs backwards it would appear the timing is way off. As a matter of fact I would think it fires after top dead center to be able to run. You may very well have a faulty ECM causing this timing issue. Just a real strange problem I've never heard of. I've got to see how this turns out.
Old 10-11-2011, 01:01 PM
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Default RE: RCAero JC Engines & YDA Engines


ORIGINAL: FOOPED

Hey Michel I've never heard of a timing as you state. How many degrees would 9.7mm be. If your engine runs backwards it would appear the timing is way off. As a matter of fact I would think it fires after top dead center to be able to run. You may very well have a faulty ECM causing this timing issue. Just a real strange problem I've never heard of. I've got to see how this turns out.
Hi

You may be right on both counts .

This is what 9.7mm is ,................... read #7

http://www.rcaer.com/pages/Articles_and_Formulas.cfm

Thanks for tuning in

Michel
Old 10-11-2011, 08:49 PM
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Default RE: RCAero JC Engines & YDA Engines

Michel that was a great source of info and I thank all the people who posted it to help others . Sure hope you find out your delima. Never had one run backwards but have had the ECM go bad and cause the engine to kick back so hard it made me check timing several times untill I found it would change timing on its on.
Old 10-11-2011, 09:27 PM
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Default RE: RCAero JC Engines & YDA Engines

Hi Michel,

Do you have access to a spare ignition unit to compare against the original one?
Old 10-12-2011, 02:08 AM
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Default RE: RCAero JC Engines & YDA Engines


ORIGINAL: apalsson

Hi Michel,

Do you have access to a spare ignition unit to compare against the original one?
Hi

Yes I do . At the moment I have an Xoar 22 X8 , running 6400 rpm , with about slightly over a gallon of fuel through it . Please remember that it , " doesn,t " run backwards , it starts and quits abruptly .

I might be out this week-end , if weather permits . I will give the other ignition a test to observe if the rpm changes . It does seem to run hot and rough

Thanks guys

Michel
Old 10-14-2011, 04:09 AM
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Default RE: RCAero JC Engines & YDA Engines

Where can one purchase the two reed block gaskets for a JC 28? Thanks.
Old 10-14-2011, 03:49 PM
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Default RE: RCAero JC Engines & YDA Engines


ORIGINAL: JVB

Where can one purchase the two reed block gaskets for a JC 28? Thanks.
Tom at Plane Addicts is the new JC Distributer in the states. Try him.

http://www.planeaddicts.com/tips-and-tricks.shtml

I cut mine out of some blu felt gasket material from the auto parts store. It worked OK for me. May save you some time and money.
Old 10-14-2011, 04:02 PM
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Default RE: RCAero JC Engines & YDA Engines

Thanks Tom. I'm all for saving time and money.
Old 01-21-2012, 03:29 PM
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Default RE: RCAero JC Engines & YDA Engines

Hi,

Some valuable info here but so much I cant find what i am looking for. Most seem to be spinning a Xoar 18x6 on a JC 28 evo II engine at 8600rpm

I have mine running for quite a few gallons now and I am only getting 7200-7300rpm of it. I am currently 1.5turns out on low end and 1.75 turns out on top end. Engine head temp is 230 degrees F. Am i fine for temperature to lean the engine out some more to get better RPM? Or is there another reason it would spin it at this lower RPM?


Thanks

Richard

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