mpascual

My Feedback: (1)

Are you using your own blended fuel ? What type and quantity of oil are you using ?
Engine is designed to use fuel with some nitro. At hi rpm, maybe you have some missfiring. Try with glow plug included with engine (JBA #3 plug).

Regards

NM2K

My Feedback: (14)

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It means that your engine is over compressed for the load being placed upon it. You can lower the load by dropping to a 10x6 prop, or you can add a shim under the cylinder head to lower the compression.


Ed Cregger

Turk1

Yes, Im using my blend,including 18% full castor.No plug provided with engine.Thats good to know that for next time[>:]By the way,what is your impressions on JBA plugs?Worth to buy them?
Even colder plug and lesser loads comparing yours,I was thinking too,It should be misfiring.
Ed,It seems not should be a preignition because of my no nitro fuel,colder plug and lesser load comparing Spanish tests.(Same engine with same compression ratio).Do you think some methanols may ignite easier than some other methanols even with no nitro?If I use 11-8 APC instead of 11-6 Chinese prop,then no crackling sound.

XJet

Without hearing the sound it's very hard to diagnose the cause.

Sounds are often very objective one man's crackling is another's buzzing.

Once you've heard it, it's very easy to tell when an engine's detonating but I've seen a few people who simply can't hear the tell-tale sound of an engine that's grossly overcompressed.

Is it possible that what you're hearing is the prop "ripping" which would explain why it's doing it with the lighter-loaded prop (more RPMs) than with the heavier load.

If you're using a Master Airscrew then I'd say there's a very good chance your prop is ripping they rip real easy.

_________
When I'm not here I'm at [link=http://rcmodelreviews.com]RCModelReviews[/link]

Turk1

Hi XJet, that crackling is a very clear single stroke crackling.No regularity,only randomly.Richer means more frequently crackling.That is not only for JBA engine.Same sound also exists on SK engines too.Leaner adjustment also eliminates or gets down that crackling.I cant understand.Not possible but It forces me to think richness gets carburation into fluid phase and result is fluid cant be compressed in combustion chamber.

Turk1

I want to mention,Fox miracle plug cant work on my 4 SK and 1 JBA engines with my self mix fuel.Any meaning to you?Engines idles perfectly but cant get throttling and no high end run at all.Very low irregular RPM s.But OS 3 plug works great.

NM2K

My Feedback: (14)

I agree that your engine should not be preigniting using no nitro with 18% oil. Is it possible that the engine should have included a head gasket that was omitted?

The problem is as the other poster stated. What sounds like a crackle to one person, may not be the same sound to another person.


Ed Cregger

rodneygt

Here's the response and question I sent kangkeusa.com. I think it says that they are out, are expecting more and that they have an angled needle valve for nine dollars - this last part doesn't make any sense to me.

Rodney

Dear Rodney
So sorry we don't in stock for the JBA.56 engines now because sold out, about 3 weeks later new container come here, we have in stock angeled needle valve, the price is $9, if you have any question? please contact us again. thanks and have a good weekend! Peter
Peter
Tel: 631-274-3058
Fax: 631-274-3296
www.kangkeusa.com

On Fri Jan 23 22:59 , "RODNEY" sent:

I emailed you in June 2008. You did not have the JBA .56
at that time.

Do you have the JBA .56 with the swept or angeled needle
valve?

What is the stock status of your JBA and SK engines in the
USA?

Thank you,
Rodney

Turk1

Hi Rodney,though I have a private,good relations with Kangkeusa,I couldnt get a clear answer to ,why they dont bring JBA 56 both(blueline and new F type) since 2007.(Yes they dont have in stock since november 2007).
You should say F type,instead of angled needle valve carb.Kangke offering you, remote universal needle valve assembly.Their English not so great.
That F type of engines,having F type carb. are far better than SK line with old carb.Because of weather I couldnt test adequately but so far I can see those carbs are good for3D also.A little rich idling adjustment allows it to play with transition from idling to full throttle very easily while holding plane vertically.The carb design is totally different from classic two needle carbs.

Ed_Moorman

My Feedback: (1)

Looks like a copy of the OS .55AX carb.

Turk1

Hi Ed,yes it seems.There is no side slide of barrel,no side play at all and no needle into spray bar.All metering is in a hidden mechanism.

A6Ordie

I called KangkeUsa last week to see if they had any .56 F series and they told me they just got some in the week before. So I ordered one 78 bucks with shipping, but turned out it was the Blue older version. I got to read through this thread again about these, but I thought I would let anyone whos following this thread know that they do have some in stock now, just not the F series. I think I will call again today just to make sure.

A6Ordie

Well I got a JBA.56A and have been running it a bit getting it broke in and then took it to the field and flew it a few times. With an 11x7 APC at 5000 ft elev Ithought I would be getting a bit higher rpm readings, but max I could get was 11.5k. It took me a little time to get the engine to transition smoothly, but she runs good and starts darn easy. I was a little disappointed with the rpm readings, but it does seem to be a good sport engine. I was hoping it might wind up a bit more. For 80 bucks shipped though I still think it was a good buy. I'm still going to try some lower diameter higher pitch props to see if I can get some rpms and speed out of this thing.

asmund

That isa very weak engine (0.97 hp), my MVVS .49 turns that prop at 13300 rpm (1.51 hp)

Edit: added hp figures

haroldpo6

My Feedback: (10)

After reading all the post, some old, some new, are there any JBA .56F engines in the USA? Alsodoes anyone have the RPM's of the SK .50 conpaired to the JBA .56?

A6Ordie

Harold

Supposedly www.knoxhobbies.com is the new distributor and said they do have the F series. I haven't seen them on their website, but did send them an email of which they replied saying that they had them, but haven't added them to the website. As far as rpm comparisons vs the SK 50. From what I understand and have read in posts on the SK 50 it is a torque motor and is ported for lower rpm to run bigger props.
I hope to see someone here in the states get one of the F series and put it through its paces. That was what I wanted when I got the A series. I was told on the phone at Kangkeusa that they had the F series so that was what I ordered. I was a bit disappointed when I got the A series, but Ed Moorman gave a good review of the engine and it was only 80 bucks, plus I wasn't to confident on shipping it back and getting a refund.

Asmund,

I am with you on your assessment. Ithought that with the .10 more cu that it would be a bit more powerful. So far it is comparable to my Mag .46 which is no power house, but a good all around sport engine. I've seen other people get more out of their .46 engines than this thing puts out, but it is still a decent running engine so far and it wasn't to badly priced. I'll mess with it a bit more and see how it goes. It had a ton of pinch soI am not sure ifI did something wrong while breaking it in, but it still has good pinch. You got to work a little to spin it by hand. Iwouldn't think a different glow plug would do much. i have a Thunderbolt long in it I think. Also I was running 15% which should be good for it.

I'm still new to the hobby so its mostly reading stuff and trial and error. I am no engine guru by any means.

Turk1

I have found out that crackling sound was coming from rich adjustment which means some misfiring.After I got used to the engine and adjustments,no crackling at all if adjustment is right.(Despite head shim removed since then).

NM2K

My Feedback: (14)

The crackling sound that I am talking about is not caused by a rich mixture, nor does it sound anything like that sound. The engine will be screaming with a normal lean sound, but you'll hear a frying egg sound that is unmistakable in severe cases. It used to make me cringe in agony when folks would abuse their Super Tigre engines in the early seventies by burning fuel with 15% nitromethane. I couldn't afford Super Tigres back then, and here they were ruining brand new engines in front of my eyes. Ohhhh the pain (Dr. Smith from Lost In Space). 8>)


Ed Cregger

Turk1

Here is a video of my Su31, 3,060 Kg.+ fuel with JBA 56 F (muffler has baffle).
[youtube]http://www.youtube.com/watch?v=grgB3d8HsPU[/youtube]

jeffie8696

Turk nice video, thanks. Are you happy with the low speed running of your engine yet? Isee it makes plenty of power .

Turk1

Hi Jeffie,sure Im happy with low speed of my engine.No problem at all,only If I try to have marginally low speeds then I feel some transition hesitations so no need to extreme tests.

rodneygt

Has anyone sourced the F version in the U.S. yet?

bigedmustafa

My Feedback: (2)

I just maidened, Monday June 13th 2011, a new JBA .56 that I ordered from http://www.kangkeusa.com last week. I received another blue crank case version rather than the "F" series folks seem to be so intrigued with. I couldn't be more delighted, as this new JBA .56 appears to be just as powerful and reliable as the one I bought a few years ago (and still have).

The engine broke in and tuned very easily, and has been very reliable in flight. After a couple of initial tanks of fuel through it, it is now flip starting easily and reliably as well. Running it slightly rich, I measured the new JBA .56 at 13,500 rpm turning a Master Airscrew 11x5 G3 prop on 10% nitro Wildcat fuel and a Fox R/C Long glow plug.

Given the power, quality, and reliability of the blue crank case version of the JBA .56, I don't mind if I never get my hands on a new "F Series" type engine. I'll keep buying and flying these blue beauties from JBA for as long as Kangke USA can supply them.

Turk1

Hi BigEd, I too really happy with my all JBA engines.I recommend you to test a JBA 56 F.But I hear some difficulties at JBA factory after Mr.Chow s leave.

tonywayne

Are they still shipping the Old series in the US