GUYS
i have the b2.4 for some time now.
i had them both..the old verstion with the MECH ADV IGI, and the new one with the FIX pickup sensor.

both had problems!

1. prop: the minimum size is 20x8!!!!!!!!!!!!!! and this is by the manufacturer him self GARRY.
2. set is an issue, needs a lot of time...for myself and other guys more exprienced than me!
3. chk the fule system-> tank, make sure the tube is not twisted-> holes in fuel line-> for some reason the B2.4 dont like a "T" line for fueling???->try to add a ventury knob to the carb, like the ones that come on the Zenoah's...u can get one from BONZI

moreover, when this engine is tunedup and working..it is pure fun but it take time to get there.

enjoy