Probem keeping MegaTek M-16 running

[pmoyer]

Bear with me here. I'm not only new to this forum, but new to this hobby. I recently bought my son (and me) a Traxxas Stampede with a new MegaTek M-16 (.15) engine. The engine worked great for the first 4-5 tanks (thought hard to start). Now we work like crazy to get it started and once started it only runs for a short time (10-60 seconds). We sent the hi and lo screws back to factory settings with no luck. Any suggestions on what to look at next. Any help for this novice would be appreciated.

 

[Nitroaddict]

Welcome to RCNT!!!

if there is one thing i have learned - it is that every engine will start. there are only four things that make a nitro engine run:

• Fuel
• Air
• compression
• combustion

All of these things must be in effect to start. So lets check them out.

Fuel: Can you see the fuel going from the line into the carb? yes you can, as u mentioned that there was fuel in the chamber when it was flooded.
Air: Is the carb opening, is the airfilter clean? yes. u already said it was.
Compression: Is there compression? Its a new engine, so this should be okay, but u can check it by manually turning the flywheel with your thumb, it should be almost impossible to do.
Combustion: Have you checked the glow plug on the igniter while it is out of the car, and made sure it glows bright? U dont mention this, so try it first if u havnt.
-----------------------------
If all these things check out than it can only be one thing: You need to adjust the mixture of the fuel and air. It sounds to me the way u described it that you have it too rich, of course if u are breaking it in that is how u want it. set the HSN about 3/4 of turn lean, see if it starts, if it does then richen it back up once it is running. also - a great way to clear out that fuel that got in there is to pull the plug, and yank on the starter cord about 20 times, or use a box if u have one. hope this huge post helps.

 

[pmoyer]

Nitroaddict thanks for the reply.

I am getting fuel to the carb (and often do need to un-flood it), the carb is open and the airfilter is clean. I have not manually turned the flywheel, but the pull start seems rather hard to pull (so I assume I have appropriate compression).

One thing does puzzle me. The manual that came with the engine said to back off the LSN four turns (which all but unscrewed it completely) to return to factory settings. The HSN is supposed to be turned 3 times. Does that sound right to you?

Also, when we do get it to start (which is a feat in that of itself) it will slowly start to sputter, slowdown and die. If I keep the carb open, I can get it to run much longer. Also, I keep the battery attached to the glow plug it runs longer.

 

[Nitroaddict]

what u have described - seems to indicate an extremely rich setting. also curious about the ISS (idle set screw, the third screw)

Try this:

take the air filter off, with the TX & RX on, apply the brakes. Make sure that the carb isnt closing completly, but staying open about 1mm, the same as it should be at idle.

turn the HSN in (lean) 1 full turn. Turn the LSN in 1/2 turn. Attempt to restart the engine, with someone else holding the TX and 'blipping' the throttle. it should start. once running, verify that it is still running sluggish, and pouring out lots of smoke(indications of a very rich setting, good for break in). Continue with the final break in proceedures then begin leaning the needles out for maximum performance.

This should work - all that u described, indicates overly rich needle settings. this will also solve the glow plug problem, which is most likely fouling out do to the over abundance of fuel.

 

[pmoyer]

Hum, will have to look for a third screw. Didn't see one and none was mentioned in the manual (unless I overlooked it). Will check that out.

The carb does not completely close and the LSN has been adjusted to give me about 1mm of opening.

I'll try turning the HSN in (lean) 1 full turn. If I turn in the LSN 1/2 turn, won't that close the carb (or open it to much).

I'll give it a go tonight and let you know how I make out.

Thanks again for all your help. I really appreciate it.

 

[Nitroaddict]

Originally posted by pmoyer
Hum, will have to look for a third screw. Didn't see one and none was mentioned in the manual (unless I overlooked it). Will check that out.

The carb does not completely close and the LSN has been adjusted to give me about 1mm of opening.

I'll try turning the HSN in (lean) 1 full turn. If I turn in the LSN 1/2 turn, won't that close the carb (or open it to much).

I'll give it a go tonight and let you know how I make out.

Thanks again for all your help. I really appreciate it.

ATTN!!!: what u are calling the LSN IS the ISS (idle set screw) NOT the LSN. the LSN is just like the HSN, only it changes the fuel mixture at low speed. your car may not have this, but if it does, it will be sidways in the barrel itself.


read this article to further understand the carb:

http://www.rcnitro.com/rn/articles/carburetor.asp

 

[SuperMaxx97]

hey guys, on the megatech, there is only 3 needles, the hsn,lsn, and the idle. ur low speed should be set at 3 which is factory settings. i have had 2 of these engine, i had not much luck with them either. same thing happened with me. ALSO did u break the engine's in right?

bryan

 

[pmoyer]

Being a beginner, I'm sure I didn't break the engine in properly. Been learning more about that so I don't make the same mistake twice.

Finally got the MegaTek to start and stay running yesterday by adjusting the LSN. Factory settings (according to the manual) are 4 turns. I have it at about 3.75 turns out.

Still not really running smoothly though. Stalls when I give it to much throttle. Need to work on the HSN now I guess.

Assuming I need to buy another engine (which I probably do anyway) can you recommend one that is more reliable?

 

[SuperMaxx97]

that is good that u got it working half way. but breaking the engine in is the most important part of it. if u do not do it right it can mess it all up.
this engine is for a stampede right? for a new engine look at O.S they are a good company. Get something like the O.S cv-rx

bryan