Hello Pe,

I finally change out the front bearing to a double seal from RC-Bearing. I ran a couple of tanks of gas (premium and 30:1 Mobil 1 2T) without any leaks. Should I tune the "tuned pipe" before I install it? I am including a photo of the custom header. Do you have any suggestions on how to tune the engine? I have been running the engine with the stock side mount muffler(Evolution) and it runs great, it idles good, and real smooth(balanced 16x8 Xoar prop) 9000 rpm and the highest temp was 180F. I read that if you run the engine over 10,000 rpm the connecting rod bearing will fail. Do that make one that wont fail over 10,000 rpm?

Thanks,

George G. Royal

George,


The 'benchmark' prop sizes for the MVVS 26 cc engine is 18x8.

With this size prop the engine would spin at about 8,200-8,300 RPM, on the tuned-pipe.


If you need to use a smaller diameter prop, a 16x10 - 16x12 is what you need; not a 16x8! An 18x10 sizes will also work well.

As to the tuned-pipe; regard it as a 'pre-tuned' unit... I know of no one that cut and adjusted the length of the steel header...
This pipe is of cone-and-disk design, with an effective RPM range of 6,500-9,500 RPM.

I can tell you that it also works wonders on OS1.40RX, OS1.20AX and OS1.60FX engines, using suitable headers...

Amen to that.
I do know of people that run 10,000 rpm, but then the header needs to be about one inch shorter.
16x8 is too small a prop.
18x6 to18x10 is what the engine likes best, using the standard tuned pipe and header combo. plug and play hardware.