Nuno,


BIG MISTAKE!

MVVS specify in the instructions that you have in your hands (or did the shop owner throw it away?...) that you must use fuel, which is 20/80 Castor oil/methanol.

From my own experience oil with 20% oil is a complete necessity, but up to half can be replaced by a high quality synthetic lubricant. Up to 5% nitromethane can be added. But all synthetic oil will make your engine fail to perform satisfactorily.

Believe me, I tried this in several engines. What you described is exactly the behavior I encountered with less oil, and with more synthetic oil.
MVVS engines NEED a lot of Castor oil; not because they are flawed, but because this is the fuel they are designed to use.

I don't think your Diesel car will run very well if you feed it kerosene, or petrol, would it?

Luckily, MVVS engines are very robust and after replacing the fuel with the correct mix and running the engine for a few tanks, it will very likely return to its reliable self again.


The propeller you were using is too large for the engine to develop its best power.

It is the largest recommended size, so you should only use it, where low noise is more important than high power and with regular silencers only.

10.5x7 is the largest size I would recommend, with 9.5x8, 10x7, 10.5x6, 11x5, or 11.5x4 prop, depending on if you fly a fast model, or a slow one, as the recommended sizes with the tuned exhaust #3248.

The low-speed needle is there to adjust your engine's throttle behavior.

Just leaving it at the 'factory setting' will get you nowhere. You must adjust this needle to achieve the instantaneous throttle response MVVS engines are known for. It will not happen by itself.


I do hope you did a good break-in.
Use [link=http://www.rcuniverse.com/forum/Tapered%2DBore_Engine_Break%2Din_%2D_Upgraded/m_1850473/tm.htm]this thread[/link] as a guide.