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Sc 30 four stroke


Dougie Swan 1
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Just run mine this evening and ran fine. Flying it in a Quaker Flash vintage. Compression still lower than I expect but has improved a bit. Throttles well and sips fuel at a minuscule rate..

I have recently bought a piston ring and a couple of head gaskets from Just Engines so give them a try.

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Posted by Martin McIntosh on 09/06/2020 20:11:42:

Did it ever run OK? I bought one just before they stopped manufacturing and the idle needles are too short to be effective or the main jet bore is to large for them to do anything.

I bought 2 in 2007 Martin and they run like the proverbial sewing machine

The best model match have found was to put one in the little electric Seagull Decathlon, having added a flat birch ply

engine bulkhead and mount.

Recommended 10x6 prop BUT

My combo runs best through the full throttle range On a 9 x 5 prop and Laser 5% fuel

Both have run and still do, through 13 seasons and no spares required yet

Edited By Denis Watkins on 10/06/2020 10:16:03

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Some time ago I bought an SC 40 2st. which is spot on and got the 30 on the strength of this.

Phoned JE and got them to measure a new idle needle in case mine had the wrong one fitted but the sizes agreed. It would be interesting to know the length of your needle from the shoulder to the tip.

The only way that I could get a flyable idle was to drill a small air bleed hole, gradually increasing the size until it worked.

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Sorry can't measure the idle needle as it is boxed in on the model. It means taking it out to access it.

I have two SC 2 strokes, a 61 and a 53. The 61 plenty of power except the low speed throttling not perfect, but never cut out on me. The 2nd hand 53 I can't get the carb' set up at all. The idle needle seems to have more effect than the main. Very strange. Something to work on when I get round tuit.

Edited By John Wagg on 10/06/2020 13:35:14

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Posted by Martin McIntosh on 10/06/2020 11:35:25:

Some time ago I bought an SC 40 2st. which is spot on and got the 30 on the strength of this.

Phoned JE and got them to measure a new idle needle in case mine had the wrong one fitted but the sizes agreed. It would be interesting to know the length of your needle from the shoulder to the tip.

The only way that I could get a flyable idle was to drill a small air bleed hole, gradually increasing the size until it worked.

Am the same as John Wagg, Martin

The motor is in cowl, On both, but when I get one out, I will prop and cowl off and check for you.

At this moment in time, 13 years of seasonal use and storage and both idle and tickover impeccably.

I get a boost in power using 10% fuel, but am settled on Laser 5% these last few years.

Don't overprop it. These little motors like freedom

When inclined to lower noise, we stick a larger prop on, but these motors are very quiet and don't have any irritating rasp.

I could not have drilled a hole in one of mine and feel that when we sort this, then that hole needs to go

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I am using an APC 10x6, same as on my OS 26`s, and bought the motor for my Li`l Cub, no problem with the top end power but in order to use full flaps for STOL the motor needs to come down to a reliable idle. I bought it from some buffoon who stated that it had been bench tested only and as good as NIB. Every single part, including the prop. driver, has plier marks! The idle needle was screwed fully in when I got it so can see why it was sold. A complete new carb. would cost nearly as much as I paid for it. I appreciate your offer to measure your needle, but I now reckon that the main jet bore is oversize, and the jet is pressed into the body so cannot be replaced. I may just yet fill the end of the jet with solder and re drill it. I used to do similar with Kavan pressure carbs. many moons ago.

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Update Martin

Measured idle needle 18mm shoulder to tip

Now have checked both SC30s, both run well and idle well and both idle screws

Are nearly fully home

There is about half a turn from stopping fully home

So from fully in to half turn out is my ballpark idle

don't forget the main needle alters

Also, realise we use a 10 x 6 on a 40

9 x 5 or 9 x 6-10 x 5 depending on model, but my 3lb Decathlon runs a 9 x 5

Edited By Denis Watkins on 10/06/2020 16:45:47

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Acquired another SC30FS from Bill Macleod (above)(thank you) Took me a bit to get it going and quite sensitive to tuning. Idle needle about a 3/4 turn out and 1 turn for the main. Compression low but feels higher than my own original, (that's maybe how they are.) Once tuned throttles well but needs an electric starter to spin it up to get started. Not been able to start it by hand but have had a couple of spits. Used 9x6 prop' initially and then swapped to a 10x6 on the last run. The 10x6 tickover is better due obviously to flywheel effect. Using an OS'F 4 stroke plug and run on both Optimix-5 and Laser-5 fuel.

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Posted by Denis Watkins on 10/06/2020 10:14:27:
Posted by Martin McIntosh on 09/06/2020 20:11:42:

Did it ever run OK? I bought one just before they stopped manufacturing and the idle needles are too short to be effective or the main jet bore is to large for them to do anything.

I bought 2 in 2007 Martin and they run like the proverbial sewing machine

The best model match have found was to put one in the little electric Seagull Decathlon, having added a flat birch ply

engine bulkhead and mount.

Recommended 10x6 prop BUT

My combo runs best through the full throttle range On a 9 x 5 prop and Laser 5% fuel

Both have run and still do, through 13 seasons and no spares required yet

Edited By Denis Watkins on 10/06/2020 10:16:03

I find that a 9X 6 works a treat for aerobatics

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Something I forgot on my latest SC30 is the main needle felt loose so I swapped it with the one out of my SC53 two stroke. The "O" ring probably needs replacing.?

I also checked the idle needle on the 30 and, contrary to what I posted above, it is only about 1/4 turn out from fully closed.

Edited By John Wagg on 12/06/2020 18:53:35

Edited By John Wagg on 12/06/2020 19:12:34

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