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New to Four Stroke & Forum


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Firstly, Hi folks, new to the forum, just joined, and hoping some of you out there can help me.

 

I've been flying aircraft for years using Nitro 2 Stroke engines (mainly OS engines).
However, I'm scratch building a vintage aircraft and would like to delve into using a 4 stroke engine (which I've never used or seen before).
The reason for going down the four stroke route, I'm very keen to get a 'low pitch sounding' engine (something throbby).
I've previously been advised I would be much more satisfied using a four stroke to accomplish this.
Also, for the weight and size of my aircraft, I need a .40 size engine apparently.

 

So my question being to you all, please could anybody advise me on:
a/ which engine would give me the most bass (so to speak)?
b/ what fuel to use for four strokes in general?
c/ any other advice?

Very many thanks in advance, much appreciate any advise you all could give me.
Chris 🙂
 

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There are not many small 4 strokes available new these days and i think saito would be your only option for a new engine. If you dont mind 2nd hand then OS used to do a 40 and saito also did a 45 which may be of use. Enya also did 46's i think but they are generally old engines now and hard to get spares for. A laser 45 is also no good as we no longer support them for spares due to them being discontinued in about 1986. 

 

Fuel is as simple as 5% nitro and 15% synthetic oil. This will cover all 2 and 4 strokes. '4stroke fuel' is a marketing ploy, all glow fuel is the same in terms of its ingredients. I would recommend this https://www.modelshopleeds.co.uk/catalog/product_info.php?keywords=laser&sort=1a&products_id=85093. Make sure you do not buy the low oil version by accident. That is only suitable for Laser engines, but this 15% oil version is fine for everything. Stick and OS F plug in it and off you go. 

 

Beyond that 4 strokes are nothing to be scared of and in fact you might find you prefer them. I certainly do and fly only 4 stroke from ASP, OS, Enya, Saito and Laser. Some advocate tuning with a tacho but this is not a good idea for a variety of reasons. On board glow support is also talked about and again, this is not required if the engine is set up correctly. 

 

Which model are you going to power with the engine? No doubt someone here will have built one!

 

 

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Good Morning Captain and a hearty welcome to the forum from me!

 

I concur with everything that Jon has said but I've found that my OS Fourstrokes run better on 10%-12% nitro. The Lasers are fine on5%.

 

I've just done a swift inventory of the fourstrokes I own. It amounts to nine Lasers rtanging from an old 62 to a new 160 V twin; seven OS Surpass from a little 26 to a 70: three Thunder Tigers and single examples from ASP and Magnum. I bought all of the Thunder Tigers brand new and four of the Lasers, the rest were all second hand and with one exception ran well from the start.

 

As Jon says the only 40 size fourstroke currently available is the Saito. I have never owned a Saito but they have an excellent reputation and a staunch following.

 

I have recently fitted an OS 40 Surpass to a Double Size Vic Smeed Tomboy. This model has a six foot (180cms) wingspan. It flew for fifteen minutes on a four ounce (118cc) tank last week. Picture below. I am currently building a rare vintage model called a Guidato. I plan to fit it with my ASP 30 and to take both models to the vintage fly-in at Cocklebarrow Farm in Septermber. Build blog here:

Which vintage model are you building?

Last Chance Saloon (4).JPG

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4 hours ago, David Davis said:

 but I've found that my OS Fourstrokes run better on 10%-12% nitro. The Lasers are fine on5%.

 

 

 

Im quite surprised by this as my various OS's run very well on the 5% fuel i mentioned. Even the big flat 4's hang on to all 4 cylinders without issue and without glow support. I have 6 OS 4 strokes now (sold many of them years ago) with only 2 in service. I have one saito 45 and 2 enya 4 strokes in service. I am yet to find an engine that wont run properly on a 5/15 mix. 

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1 hour ago, Jon - Laser Engines said:

 

Im quite surprised by this as my various OS's run very well on the 5% fuel i mentioned. Even the big flat 4's hang on to all 4 cylinders without issue and without glow support. I have 6 OS 4 strokes now (sold many of them years ago) with only 2 in service. I have one saito 45 and 2 enya 4 strokes in service. I am yet to find an engine that wont run properly on a 5/15 mix. 

That's because you have properly installed them and know what you are doing,🥳 10% nitro makes them easier to tune.

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47 minutes ago, Paul De Tourtoulon said:

That's because you have properly installed them and know what you are doing,🥳 10% nitro makes them easier to tune.

 

Using a fuel to bandage a bad installation is not exactly something that should be recommended. If the engine is not installed properly then why not fix that problem? As for knowing what i am doing, i didnt always know i had to learn. Again, fix the problem dont try and cheat round it.  

 

5% nitro is more than sufficient and additional nitro actually makes it more difficult to tune engines accurately as they loose the peak in their tuning response leading to very inaccurate tuning and, normally, excessive fuel consumption. 

Edited by Jon - Laser Engines
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I don't believe you can use a fuel to bandage a poor instalation, thought it was a light hearted comment myself.

For me there are basics to get right, once done, use the fuel of your choice, it's just personal preference at the end of the day.

I mostly used 10% nitro, believed it gave me a better throttle response on my heli, so stuck to it for all my models. Fuel economy on a 40FS ain't even a question they sip the stuff. Set up and tune right is 99% of successful use.

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6 minutes ago, Paul De Tourtoulon said:

How many modelists know how to install an engine properly also what fuel, plug and prop for their plane ?.

 

If they don’t know the basics of installation and can’t read the destructions then they shouldn’t be flying as it doesn’t bode well for the rest of their model building.

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Sorry Paul but i agree with the other guys. If you dont know something then you need to go and find out. While it could be argued that i see engine operation in a more granular detail and with greater knowledge of the mechanics its not like i was born to have some sort of telepathic connection to the engine. I just taught myself along the way, fiddled, faffed etc. Having an understanding of the basic mechanics and laws of physics is a help, but do dont need a phd to get this stuff right. 

 

The OP is a case in point. He is new to 4 strokes, so asks for information to learn about them. As with 2 strokes if you install them correctly and use the right fuel you more of less have the battle won and the only things to consider are differences in props and so on. 

 

Working around problems rather than dealing with them is common in model flying and i think its very much the wrong approach. Another example of this mentality would be using plastic bolts to hold your undercarriage on. Ok sure it protects the aircraft if you land badly, but if you do this regularly then perhaps look at your landings instead as broken wheels are just a symptom of a bigger problem. 

 

In my view, everyone should be given a 1cc diesel engine and told to get it going with no instructions. This is how i started when i stole an old PAW from my dads box and fiddled with it when he wasnt looking. It taught me a great deal about the interactions of mixture, ignition advance, priming etc. 

 

 

Edited by Jon - Laser Engines
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Good Afternoon to you all.

 

Firstly apologies for the delay replying, I've been away. May I just say thanks to you all for your replies, rather amazing to get such a conversation going, and to read the intricate's you speak about.

 

To add to my original post, I'm building a "Super 60" (60" wingspan hence the name). Quite the sizeable model, very much looking forward to getting it finished and in the air.
I will be flying from my local beach, where I've flown my previous models from.

 

Also good news, since writing my original question, I've now the proud owner of a OS FS-40 Four stroke engine.
Can't wait to get that fired up, hoping to notice a significantly lower pitch noise fingers crossed (no comments above about noise unfortunately).

 

Thanks again,
Chris 🙂

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I flew my seagull challenger today which is powered by that wrecked os FS40 i repaired. It was the first time i ran it on the new laser 5 fuel and it ran really well. Sadly my tx battery went flat so 2 flights was all i managed, but the engine is performing very well. I am using a 10x6 but i want high rpm to try and bed the valves in to their ruined seats. 12x5 would be ideal for the super 60

 

Is your engine new or used christof?

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  • 3 weeks later...

If you find an old four stroke on ebay etc, it might be useful for spares, ( covers, push rods and the like). Bearings can be easily  sourced from places such as Simply Bearings.

 

Get your club to noise test it, if that’s club rules. 

Edited by cymaz
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