Hello Members
I recently pulled out my old megatech nitro airstrike with a megatech .46 engine.
Last weekend I started the engine with two turns counter-clockwise and it ran fine until I tried to idle the engine to keep the plane from not moving. So I read up on some tuning tips to adjust the low speed needle but now I can't even get the engine to start. Every time I try to start it the propeller nut comes loose and I have also noticed the engine has become a but tighter at TDC.
To cut the long story short
I have read the megatech engine are know to stall and have starting problems so should I get a more reliable engine like the OS .46ax or keep trying to work on the megatech engine. The reason I ask for a new engine is a few years ago when I tried to get the plane airborne the engine failed right after takeoff and crashed twice on two different occasions which got me frustrated and made me quit.
I dont't want that to happen now if the Megatechs are known to stall.

Any help or suggestions would be appreciated.

Thank you

I am not familiar with Megatech so I cant help in regards to the engine. But if you were able to start it before you moved the LSN, you should be able to start it again.

First, get hold of the manual and find the way to reset the LSN to factory setting.
Second, remove the glow plug and eject the excess fuel that you flooded the cylinder in trying to start it. That is what is causing the tightness at the TDC. This is best done with an electric started, watch out for the spray of fuel.
Thirdly, change the glow plug. If you havent used it for some time, the plug is likely no longer useful. I am not sure whether you can use a #8 or F-Type OS plug in that, check.
Fourthly, check your fuel. I have noticed that the idle becomes more reliable with some nitro in the fuel. I suggest 5-10% and used synthetic lubricant if you can, engine will become cleaner running
Dont try to handstart the engine the next time, use an electric starter. I have found that even reliable OS engines will not start the first time with handstart and we only get more frustrated in the process and give up earlier
If nothing helped, ask a club expert to help you.

If all else fails, only then buy a new engine. The exercise you did will not be in vain, it will help you on the OS and it will help you become more comfortable with engines

Hope I helped and best of luck

Ameyam

I do not recommend using an electric starter to remove excess fuel. This can cause damage to the crankshaft and/or connecting rod. Removal of excess fuel should be done by gently turning the engine over by hand. Actually, "rocking" the engine from TDC to BDC with the exhaust port pointed down is best.

The engine you are using is a rebranded mecoa, they are true abc and have an extremely long break in period, and will not run worth a crap until about a gallon of fuel is through them. Mine did not run right until near two gallons.

You likely need to replace the glow plug,these engines are hard on them for a while during break in.

If you have not gone through the break in process very well with this engine it is going to be a pain to keep running.
Here is a link to the manufacturer instruction list.

http://www.mecoa.com/mecoa/guide.htm

You may try reposting in the engine forum, a lot of the guys there are awesome with engine problems, and will know a lot about the mecoa. I found out there how to get mine running correctly, it ran, just not right. The nitro airstrike was my first glow plane also. I had a lot of problems with it, but it turned out ok.

Seems like a lifetime ago.

Good Luck

That sounds like good advice (move it to the Engine forum).

Garfield81, I can take care of that for you if you want me to. Just let me know.

CGr.

Thanks for all your replies
Some clarifications/questions:
Don't know what LSN is and how to reset?
I have been trying to find the manual online with no luck. So thanks for the Mecoa guide suggestion. I will read through it.
I used a new glow plug te first time when I got it to start which was a week ago. Should I sill replace it. The glow plug ignitor meter shows green when plugged.
I am already using a electric starter as I don't think there is any way this engine will start manually.
How can I move the post to the engine section or will the moderators have to do so.

Thank you for all your suggestions. I feel I am more armed with things to try the next time I get to play around with it.

Also I forgot to mention this but I removed the cylinder head and used a little bit of WD-40 spray hoping to smooth out the engine and remove any goo.

I can move it.

The LSN is the Low Speed Needle. It's in different locations on different engines. Perhaps someone in the general Engine forum can help you find a manual, or is familiar with that particular engine and can help you with that adjustment.

I will leave a link here in this forum so it will be easy to find once I move it on over.

CGr.

Thanks CJ. The LSN is more of a screw in the engine which I didn't know about until about a week ago so it should be at factory default settings.

An electric starter is great for clearing a flooded engine. You simply remove the glow plug and spin the engine . Shield your eyes cause it tends to spray out vigorously. It is a good way to clear out after run oil before starting, you drip some fuel into the engine and spin it.

Jeffie,
Thanks I will try that. Also hard should the prop be to turn when the piston is at the TDC? The reason I ask is if the piston is sitting at TDC and I try to turn the prop it feels like it's jammed but once I get it into motion then due to the momentum it feels a little loose.
When I opened up the head I saw there is a cylinder sleeve around the piston that is pushed up a notch when the piston reaches TDC. Is that normal? Should the piston be pushing up on the cylinder sleeve? My initial guess was that is how it pulls in the fuel but I may be wrong.

removing the glow plug to get rid of excess fuel has worked for me(19+ years) but yes your method works too,, it can be a little awkward though and i only resort to it on hard to reach cowled engines

As long as the glow plug is removed, your method is easier. I don't think the post I was answering clarified that. My apologies if it did.

I don't know about Megatech engines. Just get the O.S. 46AX and you'll be fine. They run right out of the box, no problems.

If you just pulled the top off of the head and did not remove the sleeve it is fine, just re tighten in a X pattern. The reason you feel so much pressure at TDC is the pinch these ABC engines have.

It will take a lot of running before this eases up. It should always have some pinch. If it is real tight it will move the sleeve without the head capped.

The factory setting for the LSN is 2 turns out. It is likely close and should be moved tiny amounts at a time. It is inside the carb barrel in the center of the control arm on the carb. Opposite of the HSN.

The reason you may need to replace a glow plug is new engines can wear a ton and get trash on the coil. Its worth a shot. First do what everyone else suggested and clear the excess fuel out of the engine. Then give it a spin. If it still won't fire try a new glow plug.

If you get it running again it really needs to go through a break in.

Here are some break in instructions from another brand that are as good as any. I hope this is not overkill but I figured it can't hurt. These engines are extremely tight and really do need long run in time.

Clear the engine of fuel as
described above. Do not continue to try and start a flooded engine. The
connecting rod in the engine could be damaged. Never run the electric
starter on the engine for longer than 8-10 seconds. If the engine will not
start in 8-10 seconds something is wrong.
6. The engine should start and keep running, although it may be running
slightly rough at this time. This is normal. Allow the engine to warm up
for 15 to 20 seconds before removing the glow plug clip. Let the engine
run at this throttle setting for 30 seconds and then open the throttle to full.
21The engine should be running at full throttle, but running somewhat
rough, with a lot of fuel/oil being discharged from the muffler. This is
because the engine is running in a very rich condition–that is, more than
enough fuel is running through the engine than is needed. Run the
engine at this setting for at least five minutes.
7. After five minutes, you can start leaning the engine by turning the
high-speed needle clockwise. Never turn the needle more than 1/8 of a
turn at this point. To determine if the engine will accept having the
needle leaned, give the fuel line a quick pinch and release...just pinch
the fuel line and let go. You should hear the engine increase a bit in
RPM, with the sound going up in pitch. If the engine increases in RPM,
you can lean 1/8 of a turn. Allow the engine to run for one minute at this
setting. Now give the fuel line a quick pinch and release. Wait thirty
seconds and do it again. Do this five times. If the RPM increases all five
times, lean the high-speed needle another 1/8 of a turn. Wait one minute,
and then start the pinch and release series again. If the engine doesn’t
increase in RPM when you pinch and release, wait one minute before you
try the pinch and release series again. Don’t lean the high-speed needle
until you get an increase in RPM every time you pinch and release the
fuel line.
8. Keep repeating the “pinch and release� method until the RPM does not
change when you pinch the fuel line. You’ve leaned the engine as far as
possible. Do not ever lean the engine to the point that the RPM decreases
when you pinch the line or severe damage will result. For flying, you want
to set the high speed needle so that you get an increase in RPM when you
pinch the fuel line or when you pick up the airplane and point the nose of
your model straight up. If you hear the engine’s RPM decrease when you
22pinch and release, you must immediately turn the high-speed needle
counter-clockwise at least 1/4 turn. The decrease in RPM tells you that the
engine is too lean, and needs to be run at a richer setting for at least a few
more minutes.
The entire process detailed above can be done by the end of the second
tank of fuel, or part way into the third tank. It should take a little over 1/2
hour to get your engine ready to fly. At this point, you can adjust the idle
mixture setting.
Note: It is always safer to have the engine run a little rich. This will
increase the longevity of the engine and make throttle response more
reliable.

PhoenixAngel,
Thank you for the elaborate post but I hate to say this I actually did take the sleeve out and I think i did get it in the way it came out and re-tightened it in the X pattern. Will try all the suggestions this weekend and keep you all posted.

Thank you all again!

As long as you put it back the same way it came out, no worries.

Also I forgot to mention that upon my LHS recommendation I bought fuel with 15% nitro with 20% synthetic oil.

Garfield,


While the carburettor's needles in a new engine, are often set at the factory; the long-term significance of this 'factory setting' is virtually zilch...

The manufacturer sets them, so when the engine is started by a beginner who does no know better, it will not be running too lean.
Running too lean can obviously damage some engines, so the manufacturer is essentially insuring itself against warranty claims, law-suites, Etc..

But, if someone regards this setting as one to continue with; believe me, he's got many dead-sticks and crashes coming his way.


You first need to be able to differentiate between a 'too rich' and a 'too lean' condition. You must also understand the workings of your engine's carburettor; and know how to make it run richer and leaner, at its various RPM ranges.
Then, you can consider any rich setting the needle are at, as 'the factory setting'.

I bet we see this guy on the forum with a new nick name......"9 Fingers"

Quote:

ORIGINAL: pmerritt

I bet we see this guy on the forum with a new nick name......''9 Fingers''

Just a minute... Let me check.

Nope! I still have all 11 of them!

Ok so I was at the field this weekend and tried to fire up the engine and it virtually locks up at TDC to the point that an electric starter can't turn it over. It can only be moved past TDC using hands. We tried the removal of the glow plug method but didn't help. Do I have take the whole engine apart? Am I looking for something specific?

Garfield,


No! There probably is nothing wrong with your engine.

Please read in the first posts of [link=http://www.rcuniverse.com/forum/m_1850473/tm.htm]this RCU thread[/link].


The piston does not 'refuse' to go over TDC, due to high compression...

It probably does so because this engine has a tapered bore; and the sleeve's top is a bit too small for the piston to move into freely.

The removal of the glow-plug proves it is neither a hydaulic lock, nor an excessive compression ratio; because it would otherwise have turned over without it.


Take the engine out of your plane; mount it in a test-stand and give it the proper break-in it deserves.
To get it running you would need to heat the head and the top of the cylinder, with a proper heat-gun


There is, however, a very remote chance that the sleeve in your engine is warped/deformed, resulting in a slightly elliptical form at the top, when cold...
That would justify having the warranty work for you, if it is still in effect.


You did not inform about how, or even if, this engine ran prior to April this year...
You called it "My old Megatech nitro Airstrike with a Megatech .46 engine" after all... So, has it run and has it been used?

DarZeelon,
Thank you for your reply. When I first got the plane around 2005 the engine started up fine but would stall upon take-off. It happened twice and I got frustrated and put it back in the box. Now I decided to open the box back up and I changed the glow plug and fired it up and it ran fine and I let it run for about 5 minutes (with 2 turns on the HSN). I could see a lot of smoke which lead me to believe it was running rich. After that I tried starting it the next weekend and couldn't get it to run and started noticing the freeze at TDC.

Garfield,


Engines need to be broken-in, before being mounted in planes.

The break-in must successfully be completed, before any engine can be expected to run reliably.
Failure to do this task, will only lead to frustration.


Only after an engine runs successfully and reliably on the stand, should anyone expect it to be adjustable to run on the model.

A lot of smoke indicates nothing!
And since it is a tapered-bore engine, you must not do the break-in rich... READ THE BREAK-IN THREAD!

DarZeelon,
Yes I figure I didn't properly break in the engine but what do I do from here? Am I SOS with this engine now?

Thanks