Newbie to IC - running in different four-strokes?

[Jonathan M]

Moving over from electric to IC and have a question about running in my two engines - an ASP 70 FS and an OS FS-30 Surpass.

Running-in the ASP 70 appears from the instructions to be a full and lengthy process, using a prop of slightly smaller diameter and pitch than the flying version - and a gallon of fuel - before checking and re-tightening everything. Whereas the OS FS-30 Surpass instructions suggest only a minimal run-in to set the mixture, with no special run-in prop etc. Is this because the OS is smaller, or of different quality of manufacture, or some other reason?

Jon

[bouncebounce crunch]

G'day Jonathan.

follow the manufacturers instructions is number 1.

[Denis Watkins]

BB is right, follow the instructions. It is fair comment that the run in varies so much, but one of them is half the size and half the power. Heat dissipation is different on both and with modern materials involved, I would follow the instructions about loading the motor with various props Jon

[Jon H]

I have to confess that i would throw out the ASP instructions as they are pretty useless. The OS instructions are ok but still not the way i would run in one of their engines.

The method i would use is a slightly softer version of the method i recommend for Laser engines and if done correctly will bring the engine in quickly and give a long life.

Before you start, remove the rocker cover and apply a generous amount of oil to the rockers. After run, SAE30 or two stroke oil will be just fine. You should also turn the engine upside down and inject another generous amount of oil into the crankcase. Be sure to rotate the engine slowly to distribute all the oil. This is not totally vital on the OS the ASP have been known to be rather sparing when it comes to oiling up their engines before shipping.

Get the engine mounted on a test stand and fit a suitable prop. Something like a 12x7 for the 70 and a 9x6 for the 30. These slightly small props will allow the engine to reach a high rpm without imposing a heavy load on the engine.

Once you have sourced a suitable fuel (5% nitro and 15% fully synthetic oil will be fine but if you want to go to 18% oil to play safe from a warranty point of view you can) you are ready to go.

Mount the prop in such a position that the right hand blade (viewed from the front) is at about 2 o clock when you start to feel compression.

Fill the tank, and then open the throttle to full power. Put you finger over the carb and turn the engine over by hand. Do not use an electric starter. Once fuel has been pulled into the engine it will likely hydraulic lock. This is no problem, just turn the engine over gently a few times until most of the excess fuel has cleared. You should be able to flip the engine over without it feeling flooded.

Once this is done, turn the engine backwards until you feel the compression stroke. Bring the throttle to idle, power up the glow and with a wooden stick flick the engine backwards against compression. It should fire and will bounce back and run the correct way. If it wont go like this, keep flicking until the engine stops firing and give it a dob with an electric starter but be careful. Its very easy to break the crankshaft on small engines like the 30 so be sure the engine is not flooded.

Once its up and running, open the throttle to about 4000-5000rpm with a very rich needle setting and run it for about 2 minutes. Once thats done, open the throttle fully and lean the mixture to about 90% of maximum rpm (fully leaned off). Dont stay at full power for more than about 10 seconds, all you are looking for is getting the engine into its operating window in terms of temperature. If you dont the engine will never run in correctly as it will be too cold and the clearances will go totally out the window once the engine heats up. Once the needle is set for your 90% setting you are pretty much good to go and the rest of the tank can be run out at this needle setting. Use the throttle up and down with the occasional blast at full power for 5-10 seconds or so. Keep an eye on the engine temperature. If its cool enough to hold you are likely still rich, if its cool enough to touch but too hot to hold you will be about right, if its too hot to touch then you are starting to get a bit too warm. Also wave your finger about in the exhaust to see if any oil is being ejected. Their should be a thin film of oil on your finger. Obviously dont hold your finger there, the exhaust gasses are very hot!

After a run of about 10 minutes give the slow run needle a tweak to get the best throttle response. Most ASP engines are shipped very rich at the slow run end. Once thats done, stop the engine by pinching the fuel line and allow it to cool right down. The compression should be strong and springy by this point.

Once the engine has cooled, refuel, restart and after a quick retune to verify you are very slightly rich go and fly. Dont use full power for more than 10-15 seconds at a time and keep the small prop for the first 3-5 flights. After that its off to the races and go for whatever prop you like.

 

I know this method goes against a great deal of accepted practice but it is by far the best way to go. I have run in numerous ASP engines for club mates in this way and they have all performed better than the ones run in using the ASP instructions. While there is nothing wrong with the OS method as such, its just such a faff and makes an awful mess. The same effect can be had by running the engine in the way detailed above.

 

Edited By Jon Harper - Laser Engines on 08/09/2016 08:45:05

Edited By Jon Harper - Laser Engines on 08/09/2016 08:46:11

[Cuban8]

Concur with your method Jon, I run-in my ASPs fourstrokes in very much the same way and find that they behave very well. My oldest is a .61FS that is at least fifteen years old and still going strong on its original bearings/piston/liner and has had goodness knows how many gallons of fuel through it.

 

 

Edited By Cuban8 on 08/09/2016 10:02:01

[Martin Harris - Moderator]

Sounds very similar to the method I use which I've evolved from various instructions and words of wisdom from people I respect over the years. The only caveat is to be sure that the engine is ringed and not a variety of ABC or similar...I'm sure I've come across at least one 4 stroke engine somewhere that was (OS 70 FL?). If this is the case, I would be trying to get it to running temperature quickly with it only slightly on the rich side and getting multiple heat cycles into it before giving it some sympathetic air time.

[Jonathan M]

Mmmm... now in a quandary here!

While I bow down to the expertise and experience offered, and am tempted by the much shorter run-in process suggested, my instinct is to borrow elements from Jon's advice for the ASP 70 (e.g. pre-oil the tappets and inside the crankcase), but go with the instructions provided by JustEngines (from whom I bought the engine) for a gradual run-in:

1. 1/4 throttle, very rich for 10-12mins, then let cool and check/tighten head and backplate bolts.
2. 1/2 throttle, rich with occasional leaning (say 2min rich, 1min leaner) for 12-15mins, then let cool.
3. 3/4 throttle, rich and leaning as above, then cool.
4. Full throttle, rich and leaning, etc.
5. Full throttle etc as above for several more tanks, gradually leaning the mix until engine is happy at all throttle settings.
6. When cool, check tappets (re-set if necessary) and check/tighten all bolts.

(The OS instructions for the FS-30 Surpass already indicate a much shorter process, not dissimilar to Jon's advice.)

One other question: why hand-start with a reverse flick rather than normal rotation?

[Steve Hargreaves - Moderator]

Agree totally with Jons methodology here. The important thing is to get the engine up to or very close to it's operating temperature whilst keeping the load light & ensuring adequate lubrication. This allows to working parts to bed nicely against each other at the right tolerance & temperature. I also believe that these higher temperatures "toughen" the metals slightly too although I have no evidence for this.

Personally I always use a starter....I've never had much success with the "backward flick" method....

[Jon H]

I'm going to start this post with a bit of a disclaimer so I don't get complained at. For the price they are ASP engines are pretty much unbeatable and the service from JE is always excellent. The engines run and perform well and make an excellent first 4 stroke. I have owned many myself and they have been fine.

However

As ASP engines are inexpensive their material selection/finishing will never be as good as a higher quality brand. To be blunt, they are cheap for a reason. You don't get what you don't pay for and if you compared the crank from a laser 70 with an ASP 52 (they are similar in terms of outer dia) the ASP crank is like cooked spaghetti compared to ours. Things like their piston rings, valves etc are just not as tough as you would find from another brand.

So, running in. You cannot run in an engine unless it is at its full operating temperature. All of the components need to expand to their 'running size' so that you can run in the engine in the condition that it will face all its life. Clearly you don't want to thrash it completely, but if you run it too cold the engine will loose performance once it warms up as the clearances that you ran in perfectly at cooler settings will go much wider when its hot.

As steve rightly points out the metals in the engine, like the cast iron piston ring, will work harden as they go through heat and friction cycles (full details explaining the process from a can be found here **LINK** Don't worry that its about diesels, the materials and principals are the same). This will harden the ring and prevent wear, wear that will continue unabated with a cold run in procedure. Due to the soft material used in the ASP rings we really need to harden them up asap so they don't wear out.

I have run in ASP engines using both the method in the instructions and my method detailed earlier. The engines run in 'my way' have far better compression and have been more consistent and long lived. They still need a new ring after a year to 18 months, but that's better than the 6 months you will get otherwise.

And before someone asks why the wrong procedure is recommended in the instructions there are a few reasons but I suspect the main one is to prevent people thinking they can take their engine and thrash it to within an inch of its life straight off the bat. There is also the issue of guys, such as yourself, who are inexperienced and might not be as in tune with the engine as someone like me. They might not be able to pick up the first hint of a lean knock or other issue and may continue cooking their motor until it dies so the instructions play it safe to prevent them cooking their new engine.

In truth, if you follow my procedure, noting the parts about brief full throttle bursts, how to measure engine temperature, and checking discharge oil I doubt you will have any issue. The back flick start is an acquired trick and its easier with some engines than others. The reason for it is that if you flick forwards the engine will likely fire before top dead centre and kick back violently. I have had a 70 kick hard enough to shatter my inch diameter wooden starting stick. If you flick back, you use that kick to your advantage and the first thing the engine does after firing is kick your stick out of the way, then it opens the exhaust port and blows all the rubbish out of the cylinder. It then sucks in the fuel it needs and off we go.

As a side note, hand starting will tell you a great deal especially if the engine wont start. If you juts crank it with the electric and don't even get a fart out of it you know very little of the problem, where as an engine that will fire on a prime then stop is already telling you whats wrong. If it wont fire on a prime you again have a clue where to look. I have tried teaching the guys at my club how to do it. I think my success rate is 50%!

Also, if it will help ease your fears I will tell you how I test run a Laser 70. Once I have assembled a batch I will take them out to the test stand. I will fit a 12x6 apc prop and an OS 4 stroke plug. I use 5% nitro 15% synth oil fuel and the process is as follows:

Open throttle fully and prime engine
Flip engine over to clear prime and check feel of static compression
Turn back to compression stroke
Throttle to idle
Glow on
Backflick to start (if they don't go first time I am disappointed )
Get behind the engine and remove glow
Run for about 30 seconds at 5000rpm
Open to full throttle and tune for max rpm
Check max rpm with tacho (11000 is target for the 70)
Hold max RPM for about 20 seconds
Throttle to idle, set slow run and check idle rpm (target 2200 for the 70)
Back to full power, retune if required, and hold for another 20 seconds or so
Throttle to idle and cut off fuel supply to stop.

Total run time 3 minutes or under

Clean engine, send to customer.

They then run through the same procedure and its ready to fly.

If I build and engine for myself it wont get the above treatment. I will basically fit it to the model, start it, tune it, fly it and thrash it like an engine I have had for 5 years. Our materials allow me to do this, you wont be able to do that with the ASP, but believe me, the method I have proposed is really gentle by my standards and will be just fine for the ASP and the OS

 

Edited By Jon Harper - Laser Engines on 08/09/2016 23:14:49

[Dai Fledermaus]

John I really would appreciate your advice re my ASP 30FS. I can start both my ENYA ss30 and Enya 09 Quicky by hand very easily, I don't like using a starter on them. However I just can't get on with a ASP 30FS I bought about 18 months ago. It's a real so and so to get started.

In a test stand ( I haven't flown it yet ) when I prime it to draw fuel out of the tank, fuel floods out of the air intake. I've tried flipping the prop forwards, I tried flipping it backwards but I just can't get it to start consistently well enough. It's very hit and miss. Actually it's more miss than hit. Also, as it tries to fire, fuel then runs back along the fuel line to the tank, so I'm back to the priming process again and even more flipping. I've tried to mount the fuel tank in various positions, but that made little difference.

The only way I can be sure of starting it is to use a starter running the risk of damage as you suggest, At the moment I've given up on it and it's languishing back in it's box.

[Jonathan M]

Thanks Jon for your superb explanations - I'm going to follow your advice to the letter.

[Jon H]

No problem Jonathan. As long as you keep the lubrication up and temperature under control you will be in great shape.

When it comes to temperature, just to clarify my earlier comments, if you can hold the cylinder its too cold. If you can touch it for 1-2 seconds before it burns then you are probably looking at about 75-90'c which is not bad and is also typical for most car engines . If however you cant even touch it, and/or you lick your finger and feel it sizzle as soon as you touch the engine you are over 100'c which is getting a bit toasty. If you are seeing over 100'c don't panic, up to about 125'c is fine but only once the engine is run in. Generally though I would not be comfortable with an engine that ran constantly over 100'c. Peaks at pull power are one thing, but if its that hot all the time something is not right. Some engines run hotter than others. Our Laser 240v is like a nuclear reactor when running on a small prop at high rpm. I can easily hit over 130'c on an open air test bench and this is why we make special note of the cooling requirements of the 240v when selling them. They aren't difficult to cool, its just more important. than our other engines. The ASP 70 is not in the same league and I wouldn't expect more than 100'c on the head

Dai, the little 4 strokes can be tricky to start by hand especially if the ring is not sealing well for some reason. The fuel flowing back to the tank could be from either a tank position that is quite low or the engine is turning over backwards and blowing the fuel back as it exhausts through the carb. This could be due to over zealous backwards flicking (it needs to be a flick rather than a firm push) or a lack of sufficient prime to get the early detonation we are looking for. When you prime the engine, do you have the throttle full open? if you have the time, shoot a video and pop it up so we can see whats happening and hopefully get to the bottom of it. I will see if I can shoot a video of how I start my saito 45 using the back flick, it might help you out

Also, everyone note that back flicking wont work when the engine is hot. In that case, use the electric start!

[Dai Fledermaus]

Thanks Jon, I'll do that as soon as I get a chance

[Jonathan M]

Its been a while, but work and other things got in the way, so only just now got the ASP 70FS going on the bench with the 12x6 running-in prop.

As Jon suggested, I applied after-run oil to the rockers and the rear of the crankshaft area (took off the back cover). There was indeed very little lubrication present! Was there anywhere else I should have done?

Set the prop to 2 o'clock and primed etc, but, although there was some compression-pressure, I just couldn't get the engine to fire using the back-flick technique, so I used the electric starter which worked fine.

Leaned the needle as instructed (started at 2.5 turns out and ended at about 1.5 turns) and finger-checked both the cylinder temperature and exhaust film of oil. All fine, hot but not excessively so.

Full throttle revs were about 10,500rpm, but couldn't get low throttle down below about 4,500rpm without the engine suddenly stopping. Tried this several times with same result. Realised this was probably something to do with the low-speed mixture, but not entirely clear how much to adjust this. No problems opening the throttle fast from this mid-setting without faltering or belching smoke, but just can't get down to tickover revs.

Jon

[Martin Harris - Moderator]

Probably too rich on the bottom end - overcooling the glow and putting out the fire...try screwing the idle mixture screw in a quarter turn at a time until it idles and then smaller increments until it idles nicely and still picks up well on fast throttle opening. A good indication of an over rich bottom end mixture is when the rpm drops noticeably when the glowstick is removed.

Edited By Martin Harris on 09/12/2016 16:52:14

[Jonathan M]

PS I assume tickover should be somewhere around 2,000 rpm?

PPS  Thanks Martin - the mysteries of IC engines are gradually being revealed!  

Edited By Jonathan M on 09/12/2016 16:51:14

[Denis Watkins]

• These motors will tickover around 2500 Jon. So visually check the throttle barrel is allowing a tiny gap for tickover airflow, and open up the low end anticlockwise one quarter turn to get things going, and this will probably go back in again clockwise an eighth of a turn to optimise the bottom end. My SC30 FS went from the box to the model, ran one tank satisfactorily with small adjustment then ran in the rest of the time in the cool air above

Edited By Denis Watkins on 09/12/2016 16:51:35

Edited By Denis Watkins on 09/12/2016 16:52:12

[Jonathan M]

Thanks Denis

I have to fess up that my test-stand throttle-linkage wasn't properly thought-through: it got oily quickly and started slipping under its cable-tie friction-hold due to engine vibes, plus the workmate kept driving forward over the asphalt drive due to the engine-thrust, then it started drizzling! So it wasn't the cleverest setup to deal with, holding a small screwdriver in one hand, the oily throttle-linkage in the other, not to mention the oily tachometer break-dancing off the mobile workmate...!

Engine and fuel-tank now cleaned and mounted in the airframe, with throttle-control properly secure via the RC system, so I'll have a much more stable platform to tweak the low-speed mixture in the garden tomorrow.

Sunday's weather looking benign, so hope to have the Acro Wot ready for its maiden flight at the club...

Edited By Jonathan M on 09/12/2016 17:20:05

[Jon H]

Good to hear the additional oil recommendation worked out! and dont worry about the hand starting thing, it takes practice. My gut feeling is the slow run is lean but that is very unusual for an ASP out of the box as they are normally rich.

I have copied this post from another thread where a chap had a similar question about a Laser 70. I hope it helps you diagnose the problem:

To best work out where you are with the slow can you describe how the engine stops. So does it just die, or will it cough and splutter and eventually stop. Also do you know your idle rpm? Most people set the idle rpm much too fast and this makes slow run tuning very difficult.

In general, the way I set slow run needles is pretty simple. Set main needle for max rpm, bring engine to idle (or as slow as it will go). In the case of the 70 2200-2500 is a good idle speed. Then observe the behaviour of the engine.

Symptoms of lean slow run mix:

A fast but smooth idle that wont slow down when trimmed without the engine stopping
Very little exhaust smoke
Stubborn starting
engine dies abruptly on pickup

Symptoms of a rich slow run mix:

Very lumpy idle with rpm that wont settle and is higher than it should be
Quite smoky
Starting can be a problem, as can flooding on engines with a curved intake tube like OS
Slow stuttering pickup.

With this information in hand i have a fair idea of if i am rich or lean. If you arent sure, open the slow run needle a full turn and that shoud more or less guarantee a rich mix. If its so rich it wont start, lean off 1/2 turn and start again.

Assuming a rich slow run, as established by looking at the symptoms above, slam the throttle fully open from idle and observe the response. close to idle, lean slow run 1/8 of a turn and do it again. Keep doing this until the engine starts to bog down on acceleration. You are now too lean, and its time to just tickle the slow run rich again until the bogging down stops and pickup is perfect. Once all that is done, double check the main needle tuning again and its time to go fly

This video shows me running through the procedure with a 150. both needles are really rich to start with and i set up the whole thing. One thing i forgot was to make sure the engine is up to running temperature which is why i leave it for a few minutes before starting to tune it.

[Jonathan M]

Thanks Jon - very clear explanation and great video! Jolly useful having an accessible knob for the slow run mixture on your Laser engines, rather than the fiddly screw-head on the ASP (which now points downwards on my side-mounted unit).

I haven't had time yet to run the engine again (albeit now in the airframe), but I think you're right about the slow run being too lean: I followed the instructions to re-set it to the factory level, which turned out to be some way out (i.e. a richer starting-point) from where I had been running it in previously.

Will see how tomorrow morning's test-runs go.

Jon

[Jon H]

No worries

[Jonathan M]

Things getting much better: slow-speed mixture now set okay so that throttle transitions up and down without faltering, although can't quite get idle speed low enough.

But seem to have another problem in that the fuel supply sometimes falters due to visible air pockets travelling up the fuel-line, even with a reasonable amount of fuel still in the 10oz tank. If the air pockets are excessive then the engine cuts completely, especially at lower revs when vibration seems to be greater (hence the problem with dealing with the slow-speed setting above). This happens with the model static on the ground and I don't know - if vibrations are the cause - if the same thing will occur when the model is eventually in flight, and with the fuel system being subject to dynamic forces as the model manoeuvres.

The model is an Acro Wot ARTF and the brand new fuel tank will need to be taken out (the usual hassle) in order to check for air-leaks. The clunk tube was cut so the clunk cleared the rear wall of the tank by about 10mm, and I tightened up the bung-screw pretty well before installing. The filler tube has one of those plastic cut-off clips and the tank is pressurised via a tube from the silencer. The only other element in the supply is a brand new fuel-filter between the tank and the carb.

If vibrations are the cause, then surely the tank should be held in suspension from the airframe using foam?

[..]

Hi Jonathan , the tanks in the ripmax ARTF kits are notoriously poor especially around the bung with many including myself having had them fall out completely so a double check or better still a new reliable replacement wouldn't hurt at all.

Yes the vibration would be eased with some foam and yes it is worse when it's static on the ground.

Also remember that running the engine in is an evolving process so the tick over will improve as the engine gets a few tank fulls through in flight.

Also personally I would ditch the on board fuel filter, I use a filter on my fill line only. Why complicate things with an inline onboard filter when you can filter the fuel as it goes in? It's just another two joints to leak. 

Edited By Justin K. on 22/12/2016 18:45:37

Edited By Justin K. on 22/12/2016 18:46:58

Edited By Justin K. on 22/12/2016 18:47:55

[Denis Watkins]

2 things of note Jonathan, one, you do have a leak somewhere in a fuel line, the bung or the tank, it is not vibration. Two, the motor needs fully running in before it will tickover reliably. Even new pipes can get nicked or split while stored and then fitted to the model. The bung is the usual culprit on a new installation

Edited By Denis Watkins on 22/12/2016 18:44:43

[Denis Watkins]

Justin, I was typing while you were, I agree with you