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SJ60L

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Old 03-20-2009, 05:56 PM
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Stripes
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Default SJ60L

Hi Bob,

I bought a nice 60L on the big auction site; it's not the LX model. I have a couple questions.

1. What size are the threads for the back case bolts. They are too big to be 4-40 and too small to be 6-32. The list of parts doesn't even mention the bolts much less tell the size. The longer one used to attach the needle to the back of the case is missing.

2. This engine runs nicely with a 10x6 Master Airscrew I had kicking around. I'm using 15% nitro. It clocks right into the 16's.

The remote needle is extremely insensitive, however. It's now four full turns open. Does that seem right?

I can run it up to the point where it just starts to loose rpm and then in order to drop 500 or so I have to back it off a full turn and more. The needle seems to have a very wide adjustment range. Is that normal?

I had a 76BSE a couple years ago and that seemed to have a wide needle too.

Steve
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Old 03-20-2009, 07:34 PM
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bob27s
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Default RE: SJ60L


ORIGINAL: Stripes

Hi Bob,

I bought a nice 60L on the big auction site; it's not the LX model. I have a couple questions.

1. What size are the threads for the back case bolts. They are too big to be 4-40 and too small to be 6-32. The list of parts doesn't even mention the bolts much less tell the size. The longer one used to attach the needle to the back of the case is missing.

2. This engine runs nicely with a 10x6 Master Airscrew I had kicking around. I'm using 15% nitro. It clocks right into the 16's.

The remote needle is extremely insensitive, however. It's now four full turns open. Does that seem right?

I can run it up to the point where it just starts to loose rpm and then in order to drop 500 or so I have to back it off a full turn and more. The needle seems to have a very wide adjustment range. Is that normal?

I had a 76BSE a couple years ago and that seemed to have a wide needle too.

Steve

The screws are 5-40 I believe. Odd size, but perfect for the job.

10x6 is good, it likes that prop. The stock 60L muffler (the longer one) runs good down to about 15,000 peak - and up to about 17,000. Prop selection should allow the engine to hit a launch rpm in that range.
Number of turns means little, except as a reference. 4 is about right.

The broad needle means the pipe is effectively "long" - which is good. Not over-propped. You do not want a critical needle or a sensitive needle. When it jumps screaming on the pipe to falling off the pipe with a 1/2 turn... then you have a problem.

However, if you lean the engine to the point where it sags in rpm (gets hot) the needle setting becomes meaningless. If it goes over the top and gets hot, it will not recover quickly. Best thing to do is richen up like you did, shut it down and let it completely cool down. Then start it again.

You want to run the engine 600-800 rpm off of peak for flight, so once you find where it turns, just use that as a reference to set it the next time.

If you need screws, let me know

Bob
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