Hi!

After a medium start (the only problem was bad transition) with the MVVS .45 (blue head) with 3 months flying and no major problems, lately it has been a TRUE HELL!!!

In my beginning I used a 11X7 prop, but recently I have changed to a 10X6 since I was always destroying the prop tips of the larger 11".

I now use a 10X6 prop and ProSynth 2000 ( I have been told by the shop owner that only has synthetic oil, and later on I read in a forum it has 17.5% content according to a test made by a chemist since no one seems to find out the true oil content of it).

The engine is hard to start;
If I raise the idle it will run OK but at a high idle it is difficult to land. If I set a good idle it always stops after I land!!!
Did I forgot to say that transition still absolutely SUCKS!!!
It chokes a lot and I have had a lot of dead-sticks.

No one seems to be able to set the high end needle correctly, not even those with more experience.

My questions are:

Should I return to the use of a larger prop?

Is it that important to use Castor oil in MVVS engines and a minimum 20% of total oil? Will I see a major improvement if I change my fuel to Castor?

Should I change the idle needle setting? It still is at the factory set 1,2 mm.

Please help me!!!

Nuno
Portugal

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.

Thank you Dar Zeelon for your help.

I will try a fuel with Castor oil and then see what happens.

Dar is totally "right on", I know because I have a 45, a 40 and a 28 MVVS . I actually aquired the 28 from Dar. I had some tuning problems with the 40 and 45 as they both were equipped with the old carb. He helped me with the new Needle setup and I now have two really impressive engines, the 28 has the new carb so is really excellent out of the box.