RE: Mystery Speed Engine Break In
 

Tom, any numbers yet?

I will start my testing with the needle 3 turns out based on your experiences, thanks for the info. Looks like it at least runs WOT.


Mark

RE: Mystery Speed Engine Break In
 

Yes, go to the thread in Glow Engines. Lots of us are discussing it there and there are numbers in there but I forget right now what they were! :p

RE: Mystery Speed Engine Break In
 

1) What will happen if I use all 3 shims and don't need them? Just less power? How do I tell if I need them or not, just pull one at a time and see how it responds?
2) Define cold? I have always just used sport engines and boring old Fox "sport" plugs. Should I be looking at OS #8 or something else?
3) Well, at least I got one thing right...
4) Seems fair to me. At least rich won't hurt anything like lean will.


1). If the motor is uncompressed, it won't unload as well in the air and it will be down on potential RPM numbers. Unfortunately, we don't have a lot of data on what these motors should turn a specific prop. I think it will take some testing.
2. I would use either a KB 1L, KB HP, or McCoy #9. The OS #8 seems to work well in just about everything, I just tend to avoid them because of their heavy price tag.
3. :)
4. Exactly, and you don't know how the coarseness of the threads will be from motor to motor. I wouldn't suspect the tolerances on these motors to be consistently close.

RE: Mystery Speed Engine Break In
 

Thread pitch won't vary from motor to motor - they have taps and dies over there. Needle valve threads wouldn't be cut with single point tools.

MJD

RE: Mystery Speed Engine Break In
 

Yeah, come on guys. lol... These motors were not made by cavemen with stone tools. Perhaps due to their economy in shambles because of the Cold War they had well worn machines and lower quality raw materials in some cases but these motors were designed and built by people who most assuredly have very high technical skills. Can we say KALISHNIKOV? MIG? SOYUZ? TUPOLEV? YAK? I personally have no qualms about Russian made products. And fine tuning this "jewel in the rough" is really fun in my opinion. ;)

RE: Mystery Speed Engine Break In
 

90% of my motors are Nelsons or Jetts.

You are right about the threads being the same, but you don't know if the needles are the same length or the threads start in the same spot. You also don't know how sharp or blunt the needle is. Opening it 3 vs 5 times from closed is no big deal, I just prefer to err on the rich side.

I have no doubt this motor will run, and most likely well, but its not even a close comparison in terms of fit and finish to the motors I normally run.

I think it is a very neat motor and I look forward to building a plane around it, so I am not knocking it.

RE: Mystery Speed Engine Break In
 

If the engines are fit with a lot of pinch, you don't want a rich break in either, the needle should be set so that the engine just breaks into a steady 2 cycle scream with plenty of oil spray in the exhaust. The idea behind under-propping is to keep the load off and the chances of overheating down, while allowing the metals to burnish in. Once the exhaust residue runs clear, then most of the break in process is over. The low speed circuit needs to be set ONLY after the engine is throughly broke in on high speed.

RE: Mystery Speed Engine Break In
 

There's a good report from Xjet in the Glow Forum.