Norvel Big Mig .25 break-in questions
 

I have just ordered a Big Mig .25 for my Tequila Sunrise and want to get it off to a good start and hopefully a good break-in. I would appreciate any advice on this engine.
I have a .074 and used the oil soak method before its first run. I have just recently found that it runs better with 20% castor oil in the fuel (25%nitro) I had problems with it locking up and throwing the prop before I started using more oil.
Please clue me in on this engine and let me know how to give it a proper break-in.
Thanks, Lynn

RE: Norvel Big Mig .25 break-in questions
 

Lynn, I've been using these engines in combat planes. First thing you want to do is to make sure that the backplate isn't leaking. I used Permatex high-temp silicone around the shoulder of the backplate to seal it. Tighten all of the bolts on the engine. Make sure that the head is tight. You'll need to buy the Norvel head tool for this (about $7).

Alternately, you can use a couple of steel pins and insert them into two of the six holes in the head (the two pins should be 180 degrees apart). Then use a screwdriver to pry between the two pins thereby tightening the head. This works OK but eventually distorts the holes in the head. The Norvel head tool works much better.

I think I used 'regular' 18% castor-synthetic / 15% nitro fuel for break-in and running. The engine is an absolute screamer on this fuel so I haven't bothered using higher nitro. If you add nitro you will also trash plugs faster. I had been using Enya #3 plugs but switched to OS A3 plugs. I may need to add another head shim because the engine still eats plugs quickly...I think there is simply too much compression.

I've been using a MA 9x4 prop on mine for break-in and running. I think I'm getting near 17K rpm out of the bushed engines...works for me!

-Tom

RE: Norvel Big Mig .25 break-in questions
 

Tom,
Glad to hear that you like this engine and for the tips. Did you do anything special to break it in?
thanks, Lynn

RE: Norvel Big Mig .25 break-in questions
 

Lynn,

This engine has (as far as I know) a plasma-ceramic coated, tapered bore sleeve and a high silicone (hypereutectic) piston.
It needs a rich, two-cycle break-in.

Don't allow it to run in four-cycle mode, for any length of time.
It may look "gentle" to you, but it is bad for the engine.

If YOUR Norvel has a ringed piston, disregard this post.

RE: Norvel Big Mig .25 break-in questions
 

Dar,
It has an alum. piston and ceramic coated sleeve and no ring. You are right about not letting it get too rich or it won't wear-in properly. I have a Norvel .074 and the .25 is made the same.

RE: Norvel Big Mig .25 break-in questions
 

Righteous!
I have the exact same setup on my Sunrise Lynn. Stand by because you are gonna have your hands full. This setup absolutely SCREAMS! If you're not careful, you'll lose it in a hurry. I broke my Big Mig in as per the instruction manual with no problems. My only problem is finding a glow plug that will give me a reliable idle. I suppose I could go ahead and shim the head for a better idle but I really want the most out of this motor and don't want to tame it too much. I would suggest though that you invest in a 6oz. fuel tank vs. the supplied 4oz. tank as the Big Mig really seems to burn up the fuel as fast as it burns up the sky, and "deadstick" landings aren't much fun with this particular airplane.
Good luck and keep us posted

RBacio
Mesquite TX

Oh yeah,
and if you find a glow plug that works well with this motor, please let me know.

RE: Norvel Big Mig .25 break-in questions
 

If your burning plugs and you think the compression is too high and you don't shim the head then consider this.
Lower your nitro percentage. Most of the European and Russian stuff is perfectly content with no nitro or 5% at most.
If you gotta have it all then get some head gaskets because it isn't just plugs that your going through, your hammering your motor too, with preignition.

RE: Norvel Big Mig .25 break-in questions
 

I will start with 15% nitro and 18% oil and see how it runs on that. From what I hear this is a 100mph plane so I hope I can keep it close. I'm used to flying 1/2 A planes so I am used to staying busy with the sticks. This plane is the same size but is about twice as fast. :)

RE: Norvel Big Mig .25 break-in questions
 

Lynn,


I will side with Dennis.

This is a European (Russian) engine that will only "get an upset stomach" from using too much nitro.
15% IS WAY TOO MUCH!

For this engine 5% is tops, unless you add a thick head gasket.
It is not designed for this and the 0-5% used for all MVVS, Rossi, Picco, OPS and Webra engines, is good for this engine too.

In a high compression engine designed to run well on no-to-low nitro, extra nitro will only give you problems. Not all engines like the same fuel.

If you don't have 0-5%, go buy some.

RE: Norvel Big Mig .25 break-in questions
 

Ok , thanks for the info. It will arrive tomorrow and I will use what Norvel recommends.