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SC52 2stroke issue.


Snorbitz
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Hi Martin...yes the fuel pipe run is not ideal but the "P" clip is there to prevent the fuel pipe touching the back plate of the spinner...its all very tight in there. The blob of orange is a fuel proof silicone to stop the pipe sliding forward through the clip with does not clamp but merely guide the pipe. During the extensive engine running i did to set the thing up no bubbles/frothing could be seen so at this stage i'm ok with the way it is.

Mr Hargreaves, You are correct the needle is a pain to get at and considering the proximity to the prop a burn would be preferable....lol. I'm not one for needle fiddling too often once its set up so yes it did take many stop/starts but i got there in the end. The fact that i could effectively flood the engine to stopping point (while the needle was too far out) tells me there's enough fuel flow i think.

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For what it's worth I believe the best thing to do is stop trying to fix an incorrect installation and start from scratch.

Take the engine out and bench mount it, set the tank up to the correct height and try setting it up. If that works it tells you the fault is with the engine/tank installation/set up

If it won't bench run, then you've got an engine issue to resolve

At the moment it's as if your looking for a solution to resolve the issue which doesn't involve taking the engine out...... the trouble is, you need to take the unit out to rule out a lot of potential issues

I'd also give serious consideration to re installing the engine in the correct orientation 180 degrees from current, Another option may be invert the engine

Good Luck

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Didn't realise that you were the other side of the world surprise may be the silencer is the right way up for you guys wink. Seriously though it's good to hear that you are making progress, I invested in a engine test stand recently to sort out an engine that I could not get to idle consistently. Definatly one of my better buys.

Paul.

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Hi Alex, the carb is on backwards I know and this was also another change I had to make to get the whole thing installed. However if you think about it even the other way around the needle will still be in the centre of the venturi and the throttle flap/roller thingy simply increases or decreases the air flow into the combustion chamber so I'm not sure this would change much. On the orientation if I fit the engine the other way up and then fly inverted which let's be honest this kind of model should do a lot of isn't that the same thing. As somebody said earlier the engine should be capable of running in any orientation and I tend to agree. Now I've got the running sorted I just need to stop the needle valve turning round in flight (I'm going to open the hole in the bodywork out and put some silicone tuube over it) I thinks it's jobs-a-goodun. One change I will be making though is on the fuel tank itself which currently is angled up towards the engine by about 15degs. It's how the instructions show it but I prefer a horizontal tank so it does not run out earlier when flying inverted. I'll take a picture of that so you can see what I mean. I had to add 15g of lead to the tail for COG so shuffling the tank back a bit might eleviate the need for the lead or so much of it anyway.

Edited By Snorbitz on 01/01/2019 18:37:54

Edited By Snorbitz on 01/01/2019 18:41:53

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Snorbitz, I had one of these models some time ago. Sadly it didn't have a happy end crying

However, I can make a couple of observations.

The fuel tank doesn't sit properly if you use the 'standard' mount supplied with the kit - this photo shows that I had the same problem you have highlighted:

2014-09-29 16.01.51.jpg

The solution, in order that the tank sits level, make a replacement support from a piece of light-ply.

You have found that the needle valve screwed itself in during flight. Looking at one of your photos, it looks as if the spring clip, which is there to prevent the valve moving, does not appear to have been installed correctly.

If you look at the following photo the tang of the spring, marked A, should be bearing against the knurled part of the needle valve marked B. That's how it looks to me! Simple remedy, slide the spring into the right position.

needle spring.jpg

Mention was made earlier of a Pitts exhaust. This one shown is exactly what I used, and can be seen in this picture.

Seagull Extra 300L-2

I agree that the noise it makes is awful !! I used it in my Peter Miller CAP20L until I couldn't stand it any longer and changed the Irvine 46 two-stroke for a four stroke - much nicer sound smiley

Cheers GDB

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Hi Caveman, I'm glad it's not just me that realized the tank install isn't correct. The way it's fitted now also does not allow for insulation. I like to encase my tanks in foam to stop foaming. I'm pretty sure the needle valve rubbing on the cowl made it spin round. It didn't happen in a whole day of running without the cowl which makes it the only difference. So I'm going to open the hole out around the valve to allow enough space for me to get some silicone hose over it. I checked the tang as you'd mentioned and it looks ok. I think just opening the hole out would do the job alone (I've never had the issue on this engine before in previous planes) but my heart can't stand another dead stick so I'm going belt and braces. It could just be that the vibrations on this model can do what has never happened on previous models. Typically in all the modelling stuff I have I don't have a peice of hose with the correct ID so a visit to town today should sort this out. Then it's flight No2.
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