Aerotec 380 Mercury 15hp 2 stroke prop pitch?

[bestman]

I'm currently running a 9 pitch prop that the engine came with.

Without a tacho I have no idea whether this is optimum.

As mentioned in a previous thread, when fully / overloaded, I'm having trouble getting on the plane.

Would a a finer pitch help? The seem to go all the way down to 5.5 but I think that is for heavy loads at displacement speeds.

[Locozodiac]

Before jumping into an empty pool guessing the right prop pitch, how about placing a Tiny Tach induction tacho, go for a wot spin with current load and compare your achieved readings to factory engine parameters. Then you will know for sure if under or over propped. Is your engine a disguissed Yam or Tohatsu model ?

A good prop selection, the one that will give slight passing midle rpm readings, good hole shot, with good top speed. If engine runs between 5 to 6K at wot, 5.5K or slight passing would be ideal. You could have 2 props, the factory standard and family oriented as spare. Inflate well that sib's tubes, a must have to perform much bettter or as expected.

Happy Sibbing

[bestman]

Thanks Locozodiac,

I think I'll do as you suggest.Would this do it?

Vespa Tiny Tach Digital Rev Counter: Amazon.co.uk: Car & Motorbike

I have no idea which disguised version I have. How do you tell?

[Locozodiac]

If it's the new standard TT-2A gasoline model, you can program spark firings for different engines, it's the one. It's a tach and hour meter as well, very usefull. The comercial tach is more expensive. About you engine if it's like this one is a disguissed Mercury made by Tohatsu.

Happy Sibbing