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Jun 12, 2018, 01:00 PM
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Question

NGH 9cc Pro. Was: Parts for a JBA .56 engine


Does anybody know when can I get a piston and sleeve for a JBA .56 glow engine?
Last edited by ululi1970; Jul 02, 2018 at 11:10 AM.
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Jun 12, 2018, 01:33 PM
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https://www.justengines.co.uk/
Jun 12, 2018, 02:19 PM
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Are the J'EN engines the same as JBAs?
Jun 12, 2018, 02:43 PM
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Try www.kangkeusa.com/skengines
Jun 12, 2018, 03:39 PM
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SeismicCWave's Avatar
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Originally Posted by TB in FG
No such web page.
Jun 12, 2018, 04:20 PM
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Try this one.

www.kangkeusa.com/jba.htm
Jun 12, 2018, 04:21 PM
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Quote:
Originally Posted by ululi1970
Does anybody know when can I get a piston and sleeve for a JBA .56 glow engine?
The JBA .56 was sold in a ringed version and an ABC version.
The ringed version's parts are identical to the NGH GT9, you can still get liners, pistons and piston rings from HobbyKing and/or Just engines.
The ABC version was sold by Just Engines under the J'EN brand name, not sure if they still have parts but you can convert to a ringed version.
I have a few JBA 56 ringed engines and a few NGH GT9 engines, nearly identical, all parts are interchangeable.
Jun 12, 2018, 05:59 PM
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Originally Posted by TB in FG
Yes working now.
Jun 12, 2018, 08:33 PM
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Quote:
Originally Posted by ClippedWings
The JBA .56 was sold in a ringed version and an ABC version.
The ringed version's parts are identical to the NGH GT9, you can still get liners, pistons and piston rings from HobbyKing and/or Just engines.
The ABC version was sold by Just Engines under the J'EN brand name, not sure if they still have parts but you can convert to a ringed version.
I have a few JBA 56 ringed engines and a few NGH GT9 engines, nearly identical, all parts are interchangeable.
MIne is the ABC version. Here's the story.

I have this engine on a Sig Somethin' Extra. It ran very well for several years, pulling close to 13,000 rpm on a 12x4 prop. I guess that the years of lean runs compromised the compression, and I ended up compensating by leaning even more, until recently it became very erratic, lots of dead sticks. Finally, I put on the bench: I can still get a decent upper range, but the mid to lower range has become near impossible to tune.

You're saying I could get a sleeve, piston and ring for these NGH GT9 engines and go with it? Looks like that would set me back $25 plus shipping, though some parts are out of stock.

As for other options, the bolt spacing (44 mm across, 18 mm along) means I can go with a OS 55 AX or a ASP/Magnum 52.
Now I am looking at these NGH GT9 engines. Actually, I would not mind switching to gas. Getting glow fuel is getting harder around here, and this is one of the planes that I use the most. Since you have both JBA 56s and NGH GT9s how do they compare? On the Somethin' extra I am limited to 12 inch props (low ground clearance). I am worried about weight. I guess I can use a smaller tank with gas, and save the extra space for the ignition, which I could feed from the rx battery...
Jun 12, 2018, 11:16 PM
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Quote:
Originally Posted by ululi1970
Since you have both JBA 56s and NGH GT9s how do they compare? On the Somethin' extra I am limited to 12 inch props (low ground clearance)....
12x6 prop is fine but I prefer 11x6 as it unloads well with both engines.
Differences between the two:
1. The GT9 Crankshaft is 5mm longer to accommodate a prop driver with a magnet.
2. The GT9 cylinder head has more fins to improve cooling.
3. The mufflers are different, the JBA comes with a larger - nitro style muffler.
4. JBA carb is better and works well with gasoline (I have one fitted to the GT9).
5. The GT9's conrod is a one piece bronze for strength, the JBA's conrod is lighter and should be well run in by now.
I use OS G5 glow plug on both the GT9 and JBA saving the weight of the ignition, you can probably use gas with muffler pressure, otherwise you can use a fuel pump actuated by crankcase pressure, the one for the RCGF10 would be a good option.
You can always continue using glow fuel or even a mixture of glow/gas.
Jun 13, 2018, 04:20 AM
The great Brutifier
Quote:
Originally Posted by ClippedWings
you can probably use gas with muffler pressure
Yes you can but it is very recommendable to make a provision for catching the crap from the muffler so it does not pollute the fuel.
Jun 13, 2018, 07:22 AM
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Quote:
Originally Posted by Brutus1967
Yes you can but it is very recommendable to make a provision for catching the crap from the muffler so it does not pollute the fuel.
Thanks Brutus, I made the comment after seeing your successful experiments, I still prefer a fuel pump.
Jun 13, 2018, 07:29 AM
The great Brutifier
Quote:
Originally Posted by ClippedWings
I still prefer a fuel pump.
I don't, given the possible faillure, and the fact that the mere presence of a fuel pump makes trouble shooting more difficult in case of any running problems (have seen a few issues lately that resembled fuel issues, caused the owner to several times overhaul the entire fuel system, but turned out to be related to the magneto, cracked carb insulator or leaky frontbearings).

What isn't there, cannot fail (duh) but also cannot set you off on the wrong foot when looking for an issue....
I choose reliability over "supercrisp throttle response" any time, a no-brainer for me.
Jun 13, 2018, 08:16 AM
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Thread OP
This thread is getting really interesting.
If I understand correctly, the idea would be to use the NGH GT9 with a G5 plug to get the benefit of gas without the extra weight of the ignition.
It may be well worth a try.

Regarding fuel pumps vs. muffler pressure, isn't a membrane pump included with the carburetor? Why else there would be a pressure tap going from
the intake side to the carb if not to provide a pulse to drive the pump (see nipple just above the NGH logo)? Unless, of course, I decide to use the JBA's carb.

One final thing: I ran all my gas engines on a 40:1 ratio using Stihl Ultra oil (synthetic, silver bottle). Would I have to use a higher oil content with this engine?
Jun 13, 2018, 08:27 AM
The great Brutifier
Yup, the latest version of the NGH9 has the pump integrated in the carb. The first type had a separate pump/regulator unit, that did not always work well and people replaced the whole assembly for either a true Walbro type, or for just a regular glow carb.

As for lubrication: I believe these engines should not be operated with less than 20:1 or so.


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