I bought a GMS .47 to replace the old OS .40 my dad got for me with my trainer; my old engine was used so I never had to break it in. I decided to go ahead and break in my new GMS today which was probably a bad idea because I have no clue how to break in an engine lol, but it was too tempting and I just couldn’t leave the engine in the box. The only thing the manual stated about break in was I shouldn’t run the engine over lean or at peaked RPM. So I ran the first two tanks at a constant full throttle really rich. I realized later that this could cause harm to the engine and seriusly reduce it's life-span ,,,? if anyone could offer any help or tips on the break in process it would be appreciated ,, Thanks

Chris,


Your GMS is a tapered-bore engine; an ABC actually.

The break-in should be done as described in [link=http://www.rcuniverse.com/forum/Tapered%2DBore_Engine_Break%2Din_%2D_Upgraded/m_1850473/tm.htm]this thread[/link].

By running it very rich, as you did, especially if it was four-cycling and still touchable, you may have shortened its life-span. It was not properly broken-in and it is best that you repeat it.


I see that you are new to RCU.
Next time, if something is unclear, it is best to ask the questions first and to proceed with the actions later.

It proved to be much cheaper that way.

There are certain perfectionist procedure regimens that some people run themselves through. They will start and run - cool down - run - etc to get the engine's parts to expand and contract to a point where they stabilize the engines parts. They do this with a combination of mixture and throttle settings.

Some people crank up the new engine and start flying them in a normal manner as if the engine was already broken in.

The manual is talking about doing it it the way you did. So another run or two and you'll be ready to go... You don't want to run a ABC engine too rich (as it will run) as it will put undue stress on the connecting rod.

Enjoy,

Jim

Run your engine about 500 rpm shy of max lean rpm and that should be sufficiently rich in a 2 stroke setting.

I saw a gentlemen at field last week take a brand new plane with never run engine, fire it up, set it 500 rpm shy of max lean rpm and take off and fly it 3 tanks worth at full throttle before he fine tuned the idle and transition. He has never broken in an engine on a stationary position. It seems brave to break one in this way but I think I'll do that next time I get a new engine.

Andy,


If it's a tapered-bore engine, it is very likely to do the trick.

But I still prefer the test-stand + 25% oil procedure.

If the engine is ringed, however, it's likely to be wasted; not broken-in.