RE: Non-OS engines
 

Ameyam, if you have to replace pistons, liners, etc, you might check into the ASP parts..... I'm not sure about the fit with the OS AX line, I know there's a lot of cross-over with the FX line.  Cheaper parts and you can replace your ABN liner with an ABC liner if that's preferable for you.  <div>
</div><div>It's hard for me to argue against OS or TT engines for reliability out of the box.  I've bought tons of beat up, worn out old OS's over the internet and with a little clean-up, they've always fired up and ran fairly well for me.  As I've progressed in the hobby and gotten more used to tuning engines and trouble-shooting, I'm starting to enjoy the Magnums and other lower cost Chinese engines.  My favorite "cheapie" so far has been an Aviatronics .46 from Sig.  $49 brand new....  was a BEAR to get the air-leaks sealed up and get it broken in, but now that it is, that engine runs like a scalded dog!  :)  It's certainly not a beginner's engine (and I certainly was when I bought it) but it delivers some pretty awesome power.</div>

RE: Non-OS engines
 

I beleve it would be an expensive mistake trying to substitute ASP/SC/Magnum parts for any of the OS AX line. While there may have been some commonality long ago perhaps the SF's or SP's maybe even the FX but I doubt that one.

The AX is a very different engine from most of those and sleeve porting is likely very different.

Sorry just my thought.

Yup Patrick I only saw one of those Avia's from Sig's big clearance. It was a new fellow who showed up with it in his new LT-40 and I helped him a bit learning how to operate the engine It was obvious it was gonna be long process getting it operating properly but he only showed up that one day and never saw it agine.

Ameyam I remember most of your long threads and the common thread (pun intended;)) did indeed seem for reasons you had to deal with that fortunately here we do not and of course that is the need for you to mix your own fuel with your local ingrediants. There is more room even here for error given the mix ratio's you may have selected.

At any rate you seem to have one of the AX's left do not give up just let it breath a little and a bit richer to give it another chance.

John

RE: Non-OS engines
 

Yes, thats the point- I have a 46 now which seems fairly new though I still have no idea why it locks up at TDC when cold. . Can you enlighten me on that? In any case, I havent warmed it up enough to find out whether it still locks at TDC when warm and it really needs to be run in properly but I never saw this tightness on any of my other engines.

The 75ax is on my old warhorse Phoenix Extra 60. That airplane has already seen the FS91 and a DLE20, so I have a fair idea how its going to fly and should be able to handle a deadstick. Like I mentioned, we ran half a tank through it recently and the LSN was fo far out (opened during the overhaul) the HSN was ineffective. Need to sort that out. The replacement piston-liner costs $109+$10 USPS + 30% customs duty, so I better try my luck with the original set first. And I dont intend to get non-OS parts as replacements

Since April, I have gone to the field just one day due to my slipped disc condition. Its getting better, so its likely I will run atleast the 75 shortly. And my flying buddy just lost the crank end on the conn rod in his 55ax. He is without a monsoon airplane, he can fly my 46 on the trainer. Lets see how it works out

Ameyam

RE: Non-OS engines
 

The .46 AX being tight at the top is normal if it's not run in yet. That's an area where there is some variation between engines because they know the running in process will get it fitted right. Since you've had some issue with breaking in engines properly, I'll offer Dub Jett's method. First, mix some fuel with no nitro and 30% castor, preferably at least half natural castor. You'll need two tanks worth, so 1/2 a liter should do. The point of the extra oil is to provide extra cooling and flush out the microscopic particles that will be produced during initial run in process without overcooling the engine with extra alcohol. Choose a prop that's an inch smaller than you plan to fly with. That should have you turning roughly the same rpm's that you will turn in flight. Heat the head to roughly operating temp and run the engine 1000 rpm off of peak for a whole tank full. The first minute should be at 1k off peak with the glow driver attached, which would probably be 2k or more off without it. After a minute, remove the glow driver and lean enough to get back to 1k of peak for the rest of the tank. After the first tank, run another full tank through the same way, then switch to standard flying fuel and do another 1k off peak run with the break in prop. After that, the engine should be able to hold a peaked needle setting with the standard flying prop, but don't run it at peak for more than a few seconds. With the engine on the plane, tune to 500 rpm off peak and tweak the low speed needle for good idling and transition, and make a few flights. Between each one you may need to tweak the needles as the settings will change as the liner continues to run in. After 3-4 flights, that should settle down and the engine will give you good reliable operation until the liner wears out many years from now.

RE: Non-OS engines
 

ok, will try that. tthis engine was run in but not fully. i had a very bad time cleaning because the one who had it didnt put in oil when storing & it was thorroughly gunked up. but i cleaned it all right.

when overhauling, i had to move the lsn out to flush. checking the manual for resetting to factory, it says 3/4 out from fully closed. that cant be right? what is the factory setting for the 46ax's lsn?

ameyam

RE: Non-OS engines
 

Why limit yourself to Tower brands? OS is very good fro ease of use, but not so good about longevity. TT and ST are somewhat better.Though TT has a QC problem with loosescrews, and ST now suffers from some of the same quality control problems as other Chinese engines. And of course Magnum is the mostubiquitous Chinese engine.The longest lived engines are probably Enya and Fox, both now sold directly from their companies. I believe both have liftime warranties. Saito makes many sizes of four strokes which are arguably better than OS.

RE: Non-OS engines
 

Quite far off the mark there, SP. I have Super Tigre and OS engines that are both over 20 years old. Where did you come up with this idea? How do you account for all the old OS engines still in use?

RE: Non-OS engines
 

If you are having problems turning the engine over, to get it started, you can use a heat gun to bring the head temp up... just don't heat your plane and ruin the covering!

Good advice.

I often recommend that ( particularly newbies ) stick with "heavy" composite props like APC's when they break in a new engine.

The nylon fill props are a bit heavier, and have a bit more mass, to help the engine through the idle and idle slower.

Once the engine is fully broken in you can switch to your favorite prop.



I'll also add, that one of the best ways of determining the LS needle setting is to put on and pull off the glow driver.

You should notice no, or just an ever so slight decrease in RPM's as you pull off the driver. If the engine slows down very noticably it is too ruch ( but you want it rich for the first run ins... )

You can then check if you've gone too far by a pinch test at idle. Pinch the fuel off and note if the engine continues to run then speeds up.

If it runs for a brief period and speeds up then dies, your fine. If it doesn't speed up before it dies, you've gone too lean.

RE: Non-OS engines
 

Time only is not a good judge.  I have engines that are almost new older than that, but very little run time so little wear.  I have not seen anything but the higer priced OS engines run for more than a few hundred hours.  Most engines only run tens of hours a year so 20 years is only about 200 to 400 hours at normal usage.  There was a report of some testing done by a fuel manufacture reported on the glow engine forum a few years back and most OS engines only lasted between 100 and 300 hours.  Some engines lasted about 2000 hours.  Many years ago Duke Fox attached one of his engines to a 55 gallon drum of fuel and lasted thousands of hours.

RE: Non-OS engines
 

I did the pinch test with the 46. It just kept running after I pinched the tubing, no change in RPM at all for 5-6 seconds. Even after that, I didnt particularly hear the rpm increase, I just didnt run much after that.

By the way, I dis-assembled the 55ax in the picture. Here are pics of the piston. Rest of the piston is quite clean, only the side that is accessible from the exhaust port side is scratched. They seem to be done manually with a screw driver or so. The piston is not generally scratched but there are a few deep scratches, deeper than the pinch around the piston, thats probably where its leaking from. Any suggestions.

Like I said, my flying buddy just loss the conn rod on his engine and his piston is stuck in the liner. If I can get the two free without too much effort, I will pit the liner and piston into my engine. That way atleast one of the two engines becomes usable

Ameyam

RE: Non-OS engines
 

That may be perfect or boardering on rich which is OK. Do a nose up test at idle as well with half a tank of fuel.

If the engine continues to run at idle you should be good to go on the LS.

RE: Non-OS engines
 

Right. Ok for the 46.

What about the 55ax piston on the pics?

Ameyam

RE: Non-OS engines
 

Your piston looks used up: heavy scoring, discolored below the crown.

My ST G34 is in a Concept 30 heli and an OS 40 FP that both have seen regular use over 20+ years. I'm not talking about shelf queens. I have 2 OS FS-26 4-strokes, a very old OS FS 61 4-stroke, a Webra .32 GT, all 12-20 years old that see frequent use and that keep on ticking. I've also seen engines ruined in one or two runs.  Operator technique is by far more important than brand. I have pals who fly 10-year-old Magnums and TT's 3 days a week, they run them hard but not too hard.

Stop tilting at windmills. Your assertion that OS engines have short lives is ludicrous.  :eek:

RE: Non-OS engines
 

Not at all, but it does depend on the engine. In general the OS 4 strokes last longer than the 2 strokes. The large and expensive engines hold up better. The older OSengines are better than the new.

Many OS engines have soft steel and rings, but quality control of fit is good. This results in a quick break in but suffers in longivity. Also a couple of OS engines I have owned suffer some bearing problems. But have had the same problem with my TT .91 four stroke as well. Not rusted out just worn out way too early.

BTW the discoloring looks like oil too me. The ABC and ACC engines build up small aluminum particles that turn the oil black. But I can not be certain from the photo's. Also the scoring doesn't look that bad, but not good either. But again hard to be certain from the photo's.

RE: Non-OS engines
 

No problem, was just a suggestion.
<br type="_moz" />

RE: Non-OS engines
 

That wouldn't jibe with my small plain-bearing engines being some of the longest-lived.

Exactly which engines are you referencing?  What Rockwell # would you call 'soft', and for what part of the engine? And what Rockwell is 'hard', and 'too hard'?

You speak in sweeping generalities, with no specific data to back up your statements. I'll just ignore your input, as it's useless.

RE: Non-OS engines
 

No, I didnt say all OS were bad, just the few I has somehow. By the way, both the 55s did a year of flying befor they went bad. The 75 started troubling in a few months.

That purple discolouration on the piston skirt is a camera artifact. Actually, the piston skirt and rest of the piston is dull gray, not shiny gray, which I think is to be expected. The scoring is only on the exhaust port side, thats where its deep

Ameyam

RE: Non-OS engines
 

<p class="MsoNormal" style="margin: 0in 0in 10pt"><span style="line-height: 115%; font-family: 'Arial','sans-serif'; font-size: 9pt">So I guess every hobbyist should have a Rockwell tester and destroy one sleeve to test and post on here? My experience with worn out engines and generally short life on OS engines, plus confirmation from very experienced modelers is enough.

I will admit that the plain bearing engines is an exception towhat I said. Probably because there are no cheap bearings to rust out or wear out.</span></p>

RE: Non-OS engines
 

I only buy OS AX. I have many of them. One 46 ax has at least 200 flights and going strong. Like some one else said here use fuel with some castor oil and don't run them lean.

RE: Non-OS engines
 

The piston in the photos is unserviceable. The matching liner will also be unserviceable. It looks as though something has caught in the piston/liner exhaust port. With ABC/ABN engines the piston and liner are a matched assembly, and you cannot change one without the other. This is even more so once the assembly has been run. To change them you should also have marked the rear face of the rod, so that the rod and the wrist pin go back together the same way they have been running. This will ensure that the oil holes in the rod, and the wear on the bushes, are all in the same relationship as before.
Evan, WB #12.

RE: Non-OS engines
 

I honestly cannot tell how people know that the scoring is to bad to be unuseable. The photo's only show black streaks. It is common for the oil and aluminum to turn such scoring black. So it is very difficult to tell how deep it is.

If it has good compression when you assemble it, and good power use it. If not,thenyou know why it does not have good power and compression.

RE: Non-OS engines
 

While a picture can't tell the whole story, the full-length damage on the piston is consistent with galling from a lean run.  If the grooves are very shallow, the OP may be able to make a few light passes with a soft stone to take off the high spots and see if it runs.

I had stored a few airplanes at a 'friend's' house during a recent move. He had a 55AX giving some trouble, so he took a brand-new one off one of my planes [X(] and 'broke it in' for me without asking my permission. The engine now has light vertical scratches, similar dark brown stains around the visible piston area, no pinch and runs hot and sometimes quits (probably seizing). When no one is around, I'll present him with the 'broken-in' engine and tell him I expect a new replacement. I doubt I'll see it, tough lesson learned.

RE: Non-OS engines
 

yes eddiec thats exactly what is happening to my engine- it starts, gets to operating temp, then loses compression. then you can turn it over with one finger without it stopping at tdc.

i know the piston-liner are a matched pair & they will cost more than half the cost of a new engine. thats why i was looking at alternate brands

ameyam

RE: Non-OS engines
 

ameyam,

If you get another 55AX, all I can say is they seem to take twice as long to break in as other engines. Patience is required. I had started to break mine in at the end of last season, even had a visiting IMAC pilot (he has several sponsorships including Futaba, not a newb) go over it and he said the same thing. I didn't get a chance to finish breaking it in, as my 'pal' broke it good.  [:o]

I hope you get yours sorted. The dark stains sometimes can indicate castor content, but in my case was overtemp. A little castor, 1 to 2%, works great for my engines. Good luck.

RE: Non-OS engines
 

that's not castor either. you are looking at a freshly washed and wiped piston.

my 46 seems to be missing a part, i am returning that one

may be this is the time to open up my fs72a

ameyam