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Jett 120

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Old 06-29-2010, 06:07 PM
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Default Jett 120

Does any one have some rpm numbers? i did some mods on my 120. i only ran it once because i bought it used and it needed a new rear bearing. with the stock muffler it turned a 15x10 at 9,800. I will be looking to run this engine at some higher RPM numbers now with the mods and will be in the 12,000 range on a 13x11 prop maybe more.
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Old 06-30-2010, 08:31 AM
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Default RE: Jett 120

It will turn if you want it to

Biggest thing you have to do is get the right muffler on it. The 12000 rpm target is at the "high" rpm range of the standard SJ-120 muffler. That likes the 9000-12000 rpm band. 10000 target.

If you have a SJ-90L muffler try with that. The engine has the torque to make it work. The regular 90L muffler works fine starting down as low as 12,500 rpm - so when unloaded in flight it should work perfectly.
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Old 06-30-2010, 10:30 AM
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Default RE: Jett 120

yes thats true already have the 90 muffler for it.

Just looking to see what everyone is getting for RPM on the smaller props.
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Old 07-01-2010, 02:34 PM
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Default RE: Jett 120

i just read fourm guidlines i guess no one else can post here. so have to take it to engine section
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Old 07-02-2010, 07:27 AM
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Default RE: Jett 120

If I run across any more info, I will let you know...

And feel free to post your results here too. Always good as a refrence.

BTW... do you have an older Big Block 120? or is it the 120L ???

Bob
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Old 07-07-2010, 05:07 PM
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Default RE: Jett 120

not sure which one it is. It is the sand cast block. not sure if a difference. Also which of the two is the strongest?
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Old 07-08-2010, 10:33 AM
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Default RE: Jett 120

If it is cast, it is the original "bigger block" engine based off the original 95 and 105 engines (and fanjett 95 engine).

Very strong engine. One of the best Dub ever made. You will not hurt it.

(if it were a SJ-120L engine, it would be machined bar stock crankcase, only available that configuration)

Several SJ-120 engines were raced over in Australia for years in the AT-6 class (midwest at-6 was the baseline design). A few ran turbo-jet mufflers and rather custom props for the event.

(oh wow... i still have this on the website.... perhaps as a reference ... http://www.jettengineering.com/hall/at6com.html )
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Old 07-14-2010, 06:57 PM
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Default RE: Jett 120

I just bought one of these engines... Are they ABC or AAC? This one has the needle on the carburetor (YEA!!) and the venturi is round and not "bathtub" shaped like the carburetor on my BSE 120.

Can you explain how these Jett Carburetors work?

I also have both 90 & 120 size mufflers.
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Old 07-14-2010, 07:11 PM
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Default RE: Jett 120

i have the stronger one. i hope to spin a 13x13 at over 12,000 on the ground will see soon.
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Old 07-14-2010, 07:22 PM
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Default RE: Jett 120

How can you tell the difference?
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Old 07-15-2010, 12:03 AM
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Default RE: Jett 120


ORIGINAL: bob27s

If it is cast, it is the original ''bigger block'' engine based off the original 95 and 105 engines (and fanjett 95 engine).

Very strong engine. One of the best Dub ever made. You will not hurt it.

(if it were a SJ-120L engine, it would be machined bar stock crankcase, only available that configuration)

Several SJ-120 engines were raced over in Australia for years in the AT-6 class (midwest at-6 was the baseline design). A few ran turbo-jet mufflers and rather custom props for the event.

(oh wow... i still have this on the website.... perhaps as a reference ... http://www.jettengineering.com/hall/at6com.html )
read this lol
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Old 07-15-2010, 07:27 PM
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Default RE: Jett 120

That's the Sport Jett 120 shown in the picture. The cast case version.[sm=confused.gif]
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Old 08-03-2010, 09:25 PM
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Default RE: Jett 120


ORIGINAL: Broken Wings

I just bought one of these engines... Are they ABC or AAC? This one has the needle on the carburetor (YEA!!) and the venturi is round and not ''bathtub'' shaped like the carburetor on my BSE 120.

Can you explain how these Jett Carburetors work?

I also have both 90 & 120 size mufflers.
This photo is the original "big block" engine. Heck of an engine.

There are two needles. High speed needle is on the left, low/mid range needle is inside of the throttle arm side (Brass screw).

The carbs are nothing mysterious. Very much like the original supertigre carbs. The low/mid speed mixture is set very close by Dub before sending them out. Instructions on the website for resetting it if the low speed has been over-tweeked a bit.

Bob
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Old 08-03-2010, 09:45 PM
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Default RE: Jett 120

I found a Gold 90 muffler. Will it work?...

How should I prop it?
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Old 08-03-2010, 10:00 PM
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Default RE: Jett 120

it may work... gold is an LX...
you need to find it running over 13000 for the gold muffler to work properly.
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