christopher small | 26/07/2014 18:17:08 |
483 forum posts 1 photos | I began running in my ASP 52 4 stroke today ,as the instructions said that came with it.First tank was fine but the second tank cut out after 2 minutes and then it wouldn`t start again fired a couple of times but wouldn`t run,then the prop kept coming loose,is this from being far too rich,needle valve 2- 1/2 turns out,throttle half open. |
Caveman | 26/07/2014 22:59:04 |
266 forum posts 237 photos | Hi Christopher As far as running in a four stroke is concerned, I think it's necessary for the engine to run really rich for the first few tankfulls, with plenty of smoke and oil from the exhaust. I wouldn't be in too much of a rush to weaken the mixture too much at this early stage I think I'm right in saying that prop-throwing is a sign of too weak a mixture. Although the running in instructions mention opening the high speed needle 2 1/2 turns, I would open it 3 or more turns, prime the engine and get it running really rich. Once it is running reliably the needle can be turned in, but not too much. These are the running in instructions for the Magnum 52 (same as ASP) four stroke Just a further thought - if you've turned the high speed needle out and the engine is still prop-throwing, could there be a blockage in the fuel supply? Perhaps it's worth checking for any muck in the needle valve assembly. Trust you haven't altered the low speed needle setting? Good luck GDB |
GrahamWh | 27/07/2014 02:43:04 |
356 forum posts 53 photos | As well as a partial blockage causing a lean mixture you could check your exhaust pressure tubing to the tank is okay and pressurising the fuel as it should. This would include making sure the silencer is still on tight, as if it gets loose you'll lose pressure too, making the fuel mix leaner. |
Bob Cotsford | 27/07/2014 04:26:23 |
7968 forum posts 439 photos | if it's not running and the prop comes loose turning it over, then tighten the prop - you are not using a wooden prop are you? They are generally considered too light for a four stroke. Have you fitted the locknut? As for failing to run, check for fuel feed as Graham suggested, also take a look at the plug, check that the wire element is a nice clean, clearly formed spiral and that it gives a good cherry red glow - it's not unknown for debris from manufacturing to damage a plug on the first run. The throttle shouldn't really need to be half open when starting, more like 1/8-1/4. Make sure it's turning freely by hand - without the plug connected, you don't want it firing while turning it over with your fingers! |
Jon - Laser Engines | 27/07/2014 09:29:54 |
4793 forum posts 179 photos | All of what has been said about running engines rich for hours at a time is wrong. Get the engine started and get it warm before leaning it off to about 90% of maximum power. Don't hold full throttle for more than about 5 seconds though. You need to do this to get the engine up to full temperature or it wont run in. Also it sounds like your engine is hugely rich and that's why its throwing the prop. ASP and SC engines normally ship with the slow run needle at least half a turn rich (for 5% fuel anyway) I build 4 stroke engines for a living and cannot understand the incorrect information written in model instructions. Edited By Jon Harper on 27/07/2014 09:31:40 |
Cuban8 | 27/07/2014 10:25:22 |
2709 forum posts 13 photos | I can only speak from the experience of running many ASP/Magnum/SC fourstrokes pretty much since they've been available in the UK. Always found them to be good value for money. Even better now some are available in Hobby King UK warehouse. For what it's worth, here's what works for me. Fully synthetic oil only these days. Never had any trouble running in with synthetic. I like Southern Modelcraft. 10% nitro OS F glowplug Fuel tank 3/4 full position level with spraybar. Keep fuel lines as short as possible. Use exhaust pressure. No inline filter - filter fuel from the bottle. First start with main needle open 2 1/2 turns, slow running set well off its seat. Engine needs to be quite wet initially. Two tank fulls through at this setting varying between 1/2 to 3/4 throttle i.e 20 minutes running. Don't worry about slow running/idle at this time. Third tank adjust for max revs on main needle then back off (rich) 1/2 turn Repeat another two tank fulls as before. Adjust for peak revs, then adjust rich by 1/8 - 1/4 turn Set slow running mixture to avoid rich cut. Check motor holds full revs (nose up) for 10 seconds. Fly engine, making sure revs are varied, avoid prolonged full throttle at all costs. These engines will only perform well after a couple of hours easy running, particularly the slow running adjustment that will only be really effective after the motor has loosened up well. When the engine's well run in, (easy to hand start) adjust top end again for peak revs, backing off by 1/16 (a couple of clicks rich) to 1/8 turn. Check that a very fine spray of oil is emitted from the exhaust (careful it's very hot, use a piece of plywood) Spend time getting slow running reliable. Hope this is of some help. Still got my original Magnum 91FS in a Chippy, just replaced the main bearings after 15 years of use, motor still running as sweet as a nut. Edited By Cuban8 on 27/07/2014 10:44:08 |
christopher small | 27/07/2014 22:00:30 |
483 forum posts 1 photos | Thanks to caveman,Graham and Bob after reading this at around 9 ish this morning I went out with a list of things to check,first of all there was a blockage in the needle valve,silencer was loose and i took spinner off prop,eventually got it run in 2 1/2 turns out leaning out at 2 1/4 turns. Jon I think you are right about the engine throwing props my MDS 40 did exactly the same,screwed the needle valve in 1/2 turn more than what the instructions said and it was fine.I wish i could build an engine. Cuban 8 thanks ,I also have a Magnum 120 fs to run in sometime for my 1/4 scale cub,probably next year,still lots to do on this ASP Chris |
Jon - Laser Engines | 27/07/2014 23:38:17 |
4793 forum posts 179 photos | Hi Cuban I follow your procedure but lean the engine off to 90% of max revs after about 3 minutes of running. I then use various power settings and don't run flat out for long. I use a small prop to keep the engine unloaded and keep touching the engine to make sure its not over heated. I use 5% nitro as there is no advantage to 10% and I never do nose up tests as they are a waste of time. Engines always richen up in the air as they unload so this test proves nothing and just makes the engine run rich |
Martin Harris | 28/07/2014 00:08:01 |
8797 forum posts 215 photos | . Edited By Martin Harris on 28/07/2014 00:08:43 |
Martin Harris | 28/07/2014 00:08:03 |
8797 forum posts 215 photos | Jon, I assume your engines use Nicasil plating directly onto aluminium bores so is your method necessarily correct for linered cylinders with cast iron rings? I'm not trying to poo-poo your advice but looking for a reason why manufacturers advise the traditional method which I have to say, has always given me satisfactory results. I'm also a little puzzled why you advise against the nose up test when again, in my experience, a model can often run satisfactorily on the ground but go lean in the air if tuned without a nose up test. Perhaps you could explain why engines go rich when they unload - it seems counter-intuitive to me (a non-expert) as the fuel flow needs to increase to match the airflow through the throttle venturi as the revs increase but the needle and fuel tubing restrictions remain the same although I appreciate that the suction will increase to largely compensate. Edited By Martin Harris on 28/07/2014 00:28:53 |
Cuban8 | 28/07/2014 08:13:57 |
2709 forum posts 13 photos | Posted by Jon Harper on 27/07/2014 23:38:17: Hi Cuban I follow your procedure but lean the engine off to 90% of max revs after about 3 minutes of running. I then use various power settings and don't run flat out for long. I use a small prop to keep the engine unloaded and keep touching the engine to make sure its not over heated. I use 5% nitro as there is no advantage to 10% and I never do nose up tests as they are a waste of time. Engines always richen up in the air as they unload so this test proves nothing and just makes the engine run rich Interesting comments Jon - not sure about engines richening when unloading in the air, my experience would suggest the opposite, especially when watching a 'needle twiddler' who screws the last 100 rpm from an engine on the ground then wonders why the motor overheats or quits a couple of minutes into a flight. Funnily enough, I've found no difference between 0% and 5% nitro, but better idle and pickup with 10% - no difference at top end though. No right or wrong, it's what works for the individual. Edited By Cuban8 on 28/07/2014 08:14:39 |
Jon - Laser Engines | 28/07/2014 09:26:28 |
4793 forum posts 179 photos | Hi guys My comments about the nose up test to refer to the correct tuning of the engine in the first place. If you happen to be one of the 'oh there's gotta be another 10 revs in there' brigade then have fun wasting your time. If however you can tune an engine to its maximum without screwing the life out of it then there is no need for the test. As for going rich in the air due to unloading the simplest way to understand it is that if you run a given prop, say 16x8 and tune the engine, if you swap to a 15x8 it will run rich with the lighter load and higher rpm so you lean it off. The opposite is true of the 17x8. Lower rpm and higher load needs more fuel. So, if the engine unloads on the 16x8....tadaa! its rich. this is most noticeable on 4 strokes as they rev lower so rpm changes are a greater % of the maximum etc. So, running in. martin you are correct in your assumption that most of my engines are nikasil on ali with iron piston rings but I have found a slightly softer version of the same method works very well with iron/steel engines. The method I use is the one suggested by Laser engines in their new instructions and it basically tells you to start the engine, warm it up and then just run it flat out at maximum power and then crack on and fly it. The only thing they ask is not to use full power for more than 10 seconds or so for the first hour and don't use huge props. As the ASP's are constructed differently I use a slightly softer approach and don't lean the engine totally like the laser. In the case of the 52 I would use an 11x6 prop, start it (by hand) after pre oiling the crankcase and rockers. After about 2 minutes at 2.5turns on the main at about 4000rpm I would open the throttle fully and lean the needle quickly until I get a good pickup in revs but nowhere near fully lean. Its then back to 4 or 5000rpm for a little bit then another blast to full power and if its still really '4 stroking' lean it slightly more. Back down again for a little while and then open up and lean to about 90% of the max and run for 5 seconds. Then back down. I would then leave this setting and just keep playing with it for 10 mins or so, I would also lean the bottom end to about 90% of its best setting. It is vital to keep an eye on the temperature and make sure there is some oil on your finger when you wave it over the exhaust outlet (don't burn yourself). But after 15 mins you should have and engine that has nice springy compression and is running well. let the engine cool fully before restarting it (look up the heat/work hardening properties of cast iron for why) and then its ready to fly. I have run in 4 ASP and SC engines for club mates like this and an Enya 155. Each has excellent compression after a good year of running (usually the asps loose it after about 6 months) and none of them have ever stopped in flight. I will soon be helping a junior member with an ASP 61 fs and will make a video if people are interested. |