I have recently acquired a MVVS 15cc engine and on its first run it started without too much fuss but on the second tank the bottom end needle vibrated out and I lost the spring. Then I assembled the engine I noticed that the spring was very weak and that the bottom end needle turned feely. I have replaced it with a, Parker ball point pen spring and it seems to be ok now. I would like to know if I received the right type of spring with the engine and if it is normal for the bottom end needle to be so lose that it can vibrate out? I understand that one should not use more than 5% nitro with this engine but I suppose this applies to see level. I fly at a 1350 meters above see level and I were wondering if at this altitude it would be ok to use 10% nitro ?

Piet,


Although MVVS does state to use only 20/80 (FAI) fuel, it is possible to use 5% nitromethane in all MVVS glow engines.

At higher altitude, such as you are at, it would probably be possible to try 10% nitro, but do be alert for possible detonation!


If any trace of detonation is noticed, go back to 5% nitro fuel.

Once the engine is run in, and the needle is set well, you will never have to readjust it. That being the case, you can use locktite to fix the needle in place so it will not budge unless you want to. At the same time the method prevents any air leaks.