Advice on Four Strokes for Newbie

[Andy-H]

As a recent novice returnee to the hobby, I have focussed on electric powered models for their simplicity, whilst I build up my experience learning to fly these blooming things, and fix them when I goof. I’m currently flying a couple of models from the Chris Foss stable. 

 

Meanwhile, I have a long standing fascination with four stroke engines (I like the noise they make), and an interest in retro models for one reason or another. Having dabbled with basic 2-stroke OS FP motors 20+ years ago, I would now quite like to have a go with a four stroke, to see if I can get the hang of them, with a view to perhaps building an Astro Hog powered by a suitable motor. I’ve therefore been looking at used motors on the BMFA classified ads. I fully appreciate there is risk associated with buying a used engine, but I’ve been watching a few YouTube videos and am comfortable that I can replace bearings etc if necessary. 

 

My inclination is to stick with OS or Saito engines, solely based on brand perception, and to buy something that looks fairly clean in the 40-50 size . Plan is to buy one (maybe two), stick it on a test stand and play with it for a while to see if I can get the hang of it. If I can, then take the whole  idea forward. 

I have a couple of questions and would very much welcome advice. 1) is it a good idea to stick to OS/Saito smaller engines to gain initial familiarity ? 2) what’s your usual practice for end-of-session clean down , particularly if the model has a cowl ? I have an old handbook (by Bill Burkinshaw) which recommends taking the cowl off and squirting oil into breather pipes, carb & glow plug apertures. Is that common practice ?
 

Would welcome any guidance on the subject. 
 

Many thanks

 

 

 

 

 

[kevin b]

Hi Andy.

I'm not very experienced with 4 strokes myself regarding rebuilding them, but you've come to the right place.

Plenty of very helpful enginistas on here.   👍

They will put you right i'm sure.

[Jon H]

There is a perception that 4 strokes are harder or more complicated to operate than a 2 stroke. This is flat out nonsense and they operate exactly the same way and have almost identical requirements. If you can run an FP series 2 stroke without problems then any modern 4 stroke will not present any issues. 

 

My recommendation is always the same. Get the tank in the right place, use the right accessories, tune for peak performance, fly until bored, go home. After run oil is a waste of time when used in the typical modeller way, and its a total faff taking the cowl off, plug out etc. You also risk damaging the plug threads taking it in and out ever session. 

 

With a 5% nitro 15% synthetic oil fuel and tuning at peak performance the risk of corrosion is low. Rich running and/or excess nitro will increase the chance of corrosion considerably so always be sure the engine is tuned correctly. 

 

 

[J D 8]

Hi,The setting up running of four strokes differs little from 2 stroke. They have the same carb set up either twin needle or airbleed.  Enya is also worth looking out for.

 Ah,Jon above got here first. Only thing I would add is store engine/model in a dry place

[Andy-H]

19 minutes ago, kevin b said:

Hi Andy.

I'm not very experienced with 4 strokes myself regarding rebuilding them, but you've come to the right place.

Plenty of very helpful enginistas on here.   👍

They will put you right i'm sure.

👍

[Andy-H]

5 minutes ago, Jon H said:

There is a perception that 4 strokes are harder or more complicated to operate than a 2 stroke. This is flat out nonsense and they operate exactly the same way and have almost identical requirements. If you can run an FP series 2 stroke without problems then any modern 4 stroke will not present any issues. 

 

My recommendation is always the same. Get the tank in the right place, use the right accessories, tune for peak performance, fly until bored, go home. After run oil is a waste of time when used in the typical modeller way, and its a total faff taking the cowl off, plug out etc. You also risk damaging the plug threads taking it in and out ever session. 

 

With a 5% nitro 15% synthetic oil fuel and tuning at peak performance the risk of corrosion is low. Rich running and/or excess nitro will increase the chance of corrosion considerably so always be sure the engine is tuned correctly. 

 

 

Thanks Jon. I did buy one years ago but came stuck/unstuck with castor oil based fuel. Gummed up completely. No idea how to handle it and of course no on-line forums to turn to for guidance so sold it.

 

If I may ask, what’s the main issue as regards tank placement ? I presume relationship with carb ? Thanks again.

 

 

 

 

[Jon H]

castor fuel can get in the bin. times have moved on.

 

for the tank, all glow engines without a pump the top of the tank should align with the middle of the carb to prevent tuning issues.

 

this image is lifted from an os manual and although it shows the tank a smidge higher, it also shows an air space we would never have so i just assume the tank is brimmed and so the fuel level and tank top are the same. 

 

[Andy-H]

Brilliant ! Thank you.  

[john stones 1 - Moderator]

My advice is simple, go buy one and enjoy it, anyone tells you they're difficult to use, ignore em.

[Andy-H]

I’m on the case …..

[David Davis 2]

I concur with all of the advice proffered so far. Nearly all of my models are fitted with four stroke engines and you won't go wrong with an OS or Saito engine but I've also had good service from engines produced by Thunder Tiger ASP, SC and Magnum. These manufacturers no longer make engines though I've had no problem finding spares for them. Then there's Laser of course...

[GrumpyGnome]

Only operating difference to 2 strokes is the need to adjust the valve clearance occasionally - just check and adjust before each flying season is plenty.

 

If you disassemble one, you need to make sure the timing of the valves is accurate but that's easy and there is plenty of guidance online.

 

Laser, OS and Saito are 'gold standard', but loads of good, serviceable other makes available - I've had good times with SC, ASP, Thunder Tiger (my Valiant currently has a 30 year old SC90 which runs beautifully).

 

As with all used engines, being able to handle it, and see it running, is ideal.

 

Buy, run, enjoy!

[Nigel R]

I concur about brand choice, for second hand. 

 

End of season, run the engine dry off possible. That's the only after run precautions I ever take.

 

Jons advice is all spot on. 

 

 

[EvilC57]

20 minutes ago, GrumpyGnome said:

Only operating difference to 2 strokes is the need to adjust the valve clearance occasionally - just check and adjust before each flying season is plenty.…

Not with an RCV!

 

Edited April 7 by EvilC57

[Paul De Tourtoulon]

Use a good oily fuel mix, an OS 'F' plug go for peak rpm on the ground then back the needle off 1/4 of a turn and put it in the air, no hanky-panky fiddling around on the ground for 1/2 an hour as it will overheat.

 

  The best 4 strokes that I have ever had were the OS .48 Surpass, and the Saito .45 S.

 

Don't even look at an RCV.😨

[GrumpyGnome]

I

41 minutes ago, EvilC57 said:

Not with an RCV!

 

 

You'd seriously recommend a used RCV to the OP?

[Simon Lumsdon 1]

Completely agree 4 strokes are straightforward and suitable for a beginner, in my experience easy to start and idle/throttle easier than 2 stoke. I have found that there are plenty NOS (unused) SC and ASP varients on ebay which are a bargain and very good, on a par with OS but much cheaper. Enjoy

Edited April 7 by Simon Lumsdon 1

[David Davis 2]

24 minutes ago, GrumpyGnome said:

I

You'd seriously recommend a used RCV to the OP?

 

A friend had one of the RCV CDs in a Puppeteer. It was quite reliable and flew the Puppeteer well enough but I've heard that these engines are not very powerful compared with poppet valve four-strokes and I can't remember what size it was. A Puppeteer would fly very well on an OS 48.

 

I own three HP VT four-strokes which I really ought to sell. These use a disc valve for the intake and exhaust function. They certainly lack power compared with a poppet valve four-stroke.

[J D 8]

 The Puppeteer likely had a 58cd in it and deliver similar power to the OS 48.

[Andy-H]

Thanks for all of your suggestions. I did wonder about some of the other brands so good to hear they are worth considering. TBH, as regards using a test bed, I had in mind using it mainly to gain familiarity with starting process, rather than letting it run for long periods. I’m quite looking forward to this.

[Cuban8]

If you can find a good OS/Saito/Laser then that's great, but ASP and SC are very good engines in my experience. My oldest 4St is a 30+ years old Magnum 91, which is another OS clone and still flys my Goldberg Chippy around with no problem. Never needed major maintenance other than a couple of new sets of bearings over its long life - compression still excellent and runs even better now on Laser 15% oil fuel.

[GrumpyGnome]

1 hour ago, Andy-H said:

Thanks for all of your suggestions. I did wonder about some of the other brands so good to hear they are worth considering. TBH, as regards using a test bed, I had in mind using it mainly to gain familiarity with starting process, rather than letting it run for long periods. I’m quite looking forward to this.

I start, and use my 2 and 4 strokes in exactly the same way. Get some fuel to the carb, apply glow, start (I use an ekectric starter), allow to run for a few seconds then remove glow, put on hat glasses and clip tx to strap, fly. 

[Engine Doctor]

Hi Andy. Welcome back to the world of IC power. Dont turn down a Enya 4C if one turns up. They are in the same class as Saito and OS for quality of materials and reliability. Spares may be an issue now but generally they last and last and are very strong.  You could also consider a smaller laser . Jon knows everything there is to know about them and can advise. 

Re laying up for winter . Corrosion will be your enemy. On the last run of the year, run the engine out of fuel while its GOOD AND HOT after flight and make sure its not running rich . Doing this will help evaporate any methanol thats got into the crankcase . Then as soon as you can give the engine a good dose of oil. In the cylinder, through the crankcase breather and inside the tappet cover etc. Dont use any fuel or oil that contains castor oil or 3in1 oil as it set like varnish . Over the years ive tried many different oils for storage and found air tool oil to be very good for this as its designed to protect air tools from any moisture in the air that powers them.

Any used engine can be a risk . With four strokes beware of any of the chinese clones that have little or no compression.  Check this with a fully open throttle;  very low or non existant compression idicates a manufacturing defect and is only fixable by fitting a new head. Also check the thread where the exhuast fits into the head . This applies to any engine with a screw in exhaust. A worn thread means a new cyl head ! Look for any nuts that have been chewed with pliers or wrong size spanners a sign of a careless owner. Lastly remove the glowplug and check thread is ok. I was caught out by that many years ago with an open rocker Enya  I bought that had the glowplug glued in ! 

Spares like castings and specialised parts for all Chinese clones are virtually imposible to find new and parts for current OS or Saito or YS engines are very expensive.

Bearings if a bit loose or noisy are easily available for virtually any fs engine and not expensive and available from any good bearing supplier.

Never be afraid of asking about engines on this forum , no question is a silly question . If your a member of a club beware of unsolisited help from the " Club Expert " look for any advice needed from an IC flyer who doesnt constantly fiddle with his engine and has consistent flights .

Good luck and enjoy the sound

Edited April 7 by Engine Doctor

[Paul De Tourtoulon]

I also have an HP .21vt, less power than a sewing machine, but cracking sound in the air and never stops, not like my *** Rcv, both gone, as ED said,

Enya 4c are really good engines 'if' you can get one.

 

Another 'tip' on 4 strokes is to leave the engine on its compression stroke, so that you don't end up with the valves sticking open.

[Engine Doctor]

All goo

16 minutes ago, Paul De Tourtoulon said:

 

Another 'tip' on 4 strokes is to leave the engine on its compression stroke, so that you don't end up with the valves sticking open.

Good  tips add up and " Many an ickle makes a muckle"